fix repos

update dependencies

.github/workflows/ci.yaml

@@ -0,0 +1,61 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+
+jobs:
+
+  lint:
+    name: Golang-CI Lint
+    timeout-minutes: 10
+    strategy:
+      matrix:
+        platform: [ubuntu-latest]
+    runs-on: ${{ matrix.platform }}
+    steps:
+      - uses: actions/checkout@v2
+      - uses: golangci/golangci-lint-action@v2
+        with:
+          # must be specified without patch version
+          version: v1.46
+  cross:
+    name: Cross
+    timeout-minutes: 10
+    strategy:
+      matrix:
+        go-version: [1.17.x]
+        platform: [ubuntu-latest]
+    runs-on: ${{ matrix.platform }}
+    steps:
+      - name: Install Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: ${{ matrix.go-version }}
+      - name: Checkout code
+        uses: actions/checkout@v2
+      - name: Cross
+        working-directory: ci
+        run: go run mage.go -v -w ../ crossBuild
+
+  test:
+    name: Unit test
+    timeout-minutes: 10
+    strategy:
+      matrix:
+        go-version: [1.17.x]
+        platform: [ubuntu-latest, windows-latest]
+    runs-on: ${{ matrix.platform }}
+    steps:
+    - name: Install Go
+      uses: actions/setup-go@v2
+      with:
+        go-version: ${{ matrix.go-version }}
+    - name: Checkout code
+      uses: actions/checkout@v2
+    - name: Test
+      run: go test -race -v ./...

.github/workflows/stale.yaml

@@ -0,0 +1,22 @@
+name: Close inactive issues
+on:
+  schedule:
+    - cron: "30 1 * * *"
+
+jobs:
+  close-issues:
+    runs-on: ubuntu-latest
+    permissions:
+      issues: write
+      pull-requests: write
+    steps:
+      - uses: actions/stale@v3
+        with:
+          days-before-issue-stale: 30
+          days-before-issue-close: 14
+          stale-issue-label: "stale"
+          stale-issue-message: "This issue is stale because it has been open for 30 days with no activity."
+          close-issue-message: "This issue was closed because it has been inactive for 14 days since being marked as stale."
+          days-before-pr-stale: -1
+          days-before-pr-close: -1
+          repo-token: ${{ secrets.GITHUB_TOKEN }}

.gitignore

@@ -1 +1,4 @@
 logrus
+vendor
+
+.idea/

.golangci.yml

@@ -0,0 +1,40 @@
+run:
+  # do not run on test files yet
+  tests: false
+
+# all available settings of specific linters
+linters-settings:
+  errcheck:
+    # report about not checking of errors in type assetions: `a := b.(MyStruct)`;
+    # default is false: such cases aren't reported by default.
+    check-type-assertions: false
+
+    # report about assignment of errors to blank identifier: `num, _ := strconv.Atoi(numStr)`;
+    # default is false: such cases aren't reported by default.
+    check-blank: false
+
+  lll:
+    line-length: 100
+    tab-width: 4
+
+  prealloc:
+    simple: false
+    range-loops: false
+    for-loops: false
+
+  whitespace:
+    multi-if: false   # Enforces newlines (or comments) after every multi-line if statement
+    multi-func: false # Enforces newlines (or comments) after every multi-line function signature
+
+linters:
+  enable:
+    - megacheck
+    - govet
+  disable:
+    - maligned
+    - prealloc
+  disable-all: false
+  presets:
+    - bugs
+    - unused
+  fast: false

.travis.yml

@@ -1,10 +1,15 @@
 language: go
-go:
+go_import_path: git.internal/re/logrus
-  - 1.2
+git:
-  - 1.3
+  depth: 1
-  - tip
+env:
+  - GO111MODULE=on
+go: 1.15.x
+os: linux
 install:
-  - go get github.com/stretchr/testify
+  - ./travis/install.sh
-  - go get github.com/stvp/go-udp-testing
+script:
-  - go get github.com/tobi/airbrake-go
+  - cd ci
-  - go get github.com/getsentry/raven-go
+  - go run mage.go -v -w ../ crossBuild
+  - go run mage.go -v -w ../ lint
+  - go run mage.go -v -w ../ test

CHANGELOG.md

@@ -0,0 +1,259 @@
+# 1.8.1
+Code quality:
+  * move magefile in its own subdir/submodule to remove magefile dependency on logrus consumer
+  * improve timestamp format documentation
+
+Fixes:
+  * fix race condition on logger hooks
+
+
+# 1.8.0
+
+Correct versioning number replacing v1.7.1.
+
+# 1.7.1
+
+Beware this release has introduced a new public API and its semver is therefore incorrect.
+
+Code quality:
+  * use go 1.15 in travis
+  * use magefile as task runner
+
+Fixes:
+  * small fixes about new go 1.13 error formatting system
+  * Fix for long time race condiction with mutating data hooks
+
+Features:
+  * build support for zos
+
+# 1.7.0
+Fixes:
+  * the dependency toward a windows terminal library has been removed
+
+Features:
+  * a new buffer pool management API has been added
+  * a set of `<LogLevel>Fn()` functions have been added
+
+# 1.6.0
+Fixes:
+  * end of line cleanup
+  * revert the entry concurrency bug fix whic leads to deadlock under some circumstances
+  * update dependency on go-windows-terminal-sequences to fix a crash with go 1.14
+
+Features:
+  * add an option to the `TextFormatter` to completely disable fields quoting
+
+# 1.5.0
+Code quality:
+  * add golangci linter run on travis
+
+Fixes:
+  * add mutex for hooks concurrent access on `Entry` data
+  * caller function field for go1.14
+  * fix build issue for gopherjs target
+
+Feature:
+  * add an hooks/writer sub-package whose goal is to split output on different stream depending on the trace level
+  * add a `DisableHTMLEscape` option in the `JSONFormatter`
+  * add `ForceQuote` and `PadLevelText` options in the `TextFormatter`
+
+# 1.4.2
+  * Fixes build break for plan9, nacl, solaris
+# 1.4.1
+This new release introduces:
+  * Enhance TextFormatter to not print caller information when they are empty (#944)
+  * Remove dependency on golang.org/x/crypto (#932, #943)
+
+Fixes:
+  * Fix Entry.WithContext method to return a copy of the initial entry (#941)
+
+# 1.4.0
+This new release introduces:
+  * Add `DeferExitHandler`, similar to `RegisterExitHandler` but prepending the handler to the list of handlers (semantically like `defer`) (#848).
+  * Add `CallerPrettyfier` to `JSONFormatter` and `TextFormatter` (#909, #911)
+  * Add `Entry.WithContext()` and `Entry.Context`, to set a context on entries to be used e.g. in hooks (#919).
+
+Fixes:
+  * Fix wrong method calls `Logger.Print` and `Logger.Warningln` (#893).
+  * Update `Entry.Logf` to not do string formatting unless the log level is enabled (#903)
+  * Fix infinite recursion on unknown `Level.String()` (#907)
+  * Fix race condition in `getCaller` (#916).
+
+
+# 1.3.0
+This new release introduces:
+  * Log, Logf, Logln functions for Logger and Entry that take a Level
+
+Fixes:
+  * Building prometheus node_exporter on AIX (#840)
+  * Race condition in TextFormatter (#468)
+  * Travis CI import path (#868)
+  * Remove coloured output on Windows (#862)
+  * Pointer to func as field in JSONFormatter (#870)
+  * Properly marshal Levels (#873)
+
+# 1.2.0
+This new release introduces:
+  * A new method `SetReportCaller` in the `Logger` to enable the file, line and calling function from which the trace has been issued
+  * A new trace level named `Trace` whose level is below `Debug`
+  * A configurable exit function to be called upon a Fatal trace
+  * The `Level` object now implements `encoding.TextUnmarshaler` interface
+
+# 1.1.1
+This is a bug fix release.
+  * fix the build break on Solaris
+  * don't drop a whole trace in JSONFormatter when a field param is a function pointer which can not be serialized
+
+# 1.1.0
+This new release introduces:
+  * several fixes:
+    * a fix for a race condition on entry formatting
+    * proper cleanup of previously used entries before putting them back in the pool
+    * the extra new line at the end of message in text formatter has been removed
+  * a new global public API to check if a level is activated: IsLevelEnabled
+  * the following methods have been added to the Logger object
+    * IsLevelEnabled
+    * SetFormatter
+    * SetOutput
+    * ReplaceHooks
+  * introduction of go module
+  * an indent configuration for the json formatter
+  * output colour support for windows
+  * the field sort function is now configurable for text formatter
+  * the CLICOLOR and CLICOLOR\_FORCE environment variable support in text formater
+
+# 1.0.6
+
+This new release introduces:
+  * a new api WithTime which allows to easily force the time of the log entry
+    which is mostly useful for logger wrapper
+  * a fix reverting the immutability of the entry given as parameter to the hooks
+    a new configuration field of the json formatter in order to put all the fields
+    in a nested dictionnary
+  * a new SetOutput method in the Logger
+  * a new configuration of the textformatter to configure the name of the default keys
+  * a new configuration of the text formatter to disable the level truncation
+
+# 1.0.5
+
+* Fix hooks race (#707)
+* Fix panic deadlock (#695)
+
+# 1.0.4
+
+* Fix race when adding hooks (#612)
+* Fix terminal check in AppEngine (#635)
+
+# 1.0.3
+
+* Replace example files with testable examples
+
+# 1.0.2
+
+* bug: quote non-string values in text formatter (#583)
+* Make (*Logger) SetLevel a public method
+
+# 1.0.1
+
+* bug: fix escaping in text formatter (#575)
+
+# 1.0.0
+
+* Officially changed name to lower-case
+* bug: colors on Windows 10 (#541)
+* bug: fix race in accessing level (#512)
+
+# 0.11.5
+
+* feature: add writer and writerlevel to entry (#372)
+
+# 0.11.4
+
+* bug: fix undefined variable on solaris (#493)
+
+# 0.11.3
+
+* formatter: configure quoting of empty values (#484)
+* formatter: configure quoting character (default is `"`) (#484)
+* bug: fix not importing io correctly in non-linux environments (#481)
+
+# 0.11.2
+
+* bug: fix windows terminal detection (#476)
+
+# 0.11.1
+
+* bug: fix tty detection with custom out (#471)
+
+# 0.11.0
+
+* performance: Use bufferpool to allocate (#370)
+* terminal: terminal detection for app-engine (#343)
+* feature: exit handler (#375)
+
+# 0.10.0
+
+* feature: Add a test hook (#180)
+* feature: `ParseLevel` is now case-insensitive (#326)
+* feature: `FieldLogger` interface that generalizes `Logger` and `Entry` (#308)
+* performance: avoid re-allocations on `WithFields` (#335)
+
+# 0.9.0
+
+* logrus/text_formatter: don't emit empty msg
+* logrus/hooks/airbrake: move out of main repository
+* logrus/hooks/sentry: move out of main repository
+* logrus/hooks/papertrail: move out of main repository
+* logrus/hooks/bugsnag: move out of main repository
+* logrus/core: run tests with `-race`
+* logrus/core: detect TTY based on `stderr`
+* logrus/core: support `WithError` on logger
+* logrus/core: Solaris support
+
+# 0.8.7
+
+* logrus/core: fix possible race (#216)
+* logrus/doc: small typo fixes and doc improvements
+
+
+# 0.8.6
+
+* hooks/raven: allow passing an initialized client
+
+# 0.8.5
+
+* logrus/core: revert #208
+
+# 0.8.4
+
+* formatter/text: fix data race (#218)
+
+# 0.8.3
+
+* logrus/core: fix entry log level (#208)
+* logrus/core: improve performance of text formatter by 40%
+* logrus/core: expose `LevelHooks` type
+* logrus/core: add support for DragonflyBSD and NetBSD
+* formatter/text: print structs more verbosely
+
+# 0.8.2
+
+* logrus: fix more Fatal family functions
+
+# 0.8.1
+
+* logrus: fix not exiting on `Fatalf` and `Fatalln`
+
+# 0.8.0
+
+* logrus: defaults to stderr instead of stdout
+* hooks/sentry: add special field for `*http.Request`
+* formatter/text: ignore Windows for colors
+
+# 0.7.3
+
+* formatter/\*: allow configuration of timestamp layout
+
+# 0.7.2
+
+* formatter/text: Add configuration option for time format (#158)

README.md

@@ -1,17 +1,46 @@
-# Logrus <img src="http://i.imgur.com/hTeVwmJ.png" width="40" height="40" alt=":walrus:" class="emoji" title=":walrus:"/>&nbsp;[![Build Status](https://travis-ci.org/Sirupsen/logrus.svg?branch=master)](https://travis-ci.org/Sirupsen/logrus)
+# Logrus <img src="http://i.imgur.com/hTeVwmJ.png" width="40" height="40" alt=":walrus:" class="emoji" title=":walrus:"/> [![Build Status](https://git.internal/re/logrus/workflows/CI/badge.svg)](https://git.internal/re/logrus/actions?query=workflow%3ACI) [![Build Status](https://travis-ci.org/sirupsen/logrus.svg?branch=master)](https://travis-ci.org/sirupsen/logrus) [![Go Reference](https://pkg.go.dev/badge/git.internal/re/logrus.svg)](https://pkg.go.dev/git.internal/re/logrus)
 
 Logrus is a structured logger for Go (golang), completely API compatible with
-the standard library logger. [Godoc][godoc]. **Please note the Logrus API is not
+the standard library logger.
-yet stable (pre 1.0), the core API is unlikely change much but please version
+
-control your Logrus to make sure you aren't fetching latest `master` on every
+**Logrus is in maintenance-mode.** We will not be introducing new features. It's
-build.**
+simply too hard to do in a way that won't break many people's projects, which is
+the last thing you want from your Logging library (again...).
+
+This does not mean Logrus is dead. Logrus will continue to be maintained for
+security, (backwards compatible) bug fixes, and performance (where we are
+limited by the interface). 
+
+I believe Logrus' biggest contribution is to have played a part in today's
+widespread use of structured logging in Golang. There doesn't seem to be a
+reason to do a major, breaking iteration into Logrus V2, since the fantastic Go
+community has built those independently. Many fantastic alternatives have sprung
+up. Logrus would look like those, had it been re-designed with what we know
+about structured logging in Go today. Check out, for example,
+[Zerolog][zerolog], [Zap][zap], and [Apex][apex].
+
+[zerolog]: https://github.com/rs/zerolog
+[zap]: https://github.com/uber-go/zap
+[apex]: https://github.com/apex/log
+
+**Seeing weird case-sensitive problems?** It's in the past been possible to
+import Logrus as both upper- and lower-case. Due to the Go package environment,
+this caused issues in the community and we needed a standard. Some environments
+experienced problems with the upper-case variant, so the lower-case was decided.
+Everything using `logrus` will need to use the lower-case:
+`git.internal/re/logrus`. Any package that isn't, should be changed.
+
+To fix Glide, see [these
+comments](https://git.internal/re/logrus/issues/553#issuecomment-306591437).
+For an in-depth explanation of the casing issue, see [this
+comment](https://git.internal/re/logrus/issues/570#issuecomment-313933276).
 
 Nicely color-coded in development (when a TTY is attached, otherwise just
 plain text):
 
 ![Colored](http://i.imgur.com/PY7qMwd.png)
 
-With `log.Formatter = new(logrus.JSONFormatter)`, for easy parsing by logstash
+With `log.SetFormatter(&log.JSONFormatter{})`, for easy parsing by logstash
 or Splunk:
 
 ```json
@@ -31,17 +60,56 @@ ocean","size":10,"time":"2014-03-10 19:57:38.562264131 -0400 EDT"}
 "time":"2014-03-10 19:57:38.562543128 -0400 EDT"}
 ```
 
-With the default `log.Formatter = new(logrus.TextFormatter)` when a TTY is not
+With the default `log.SetFormatter(&log.TextFormatter{})` when a TTY is not
 attached, the output is compatible with the
-[l2met](http://r.32k.io/l2met-introduction) format:
+[logfmt](http://godoc.org/github.com/kr/logfmt) format:
 
 ```text
-time="2014-04-20 15:36:23.830442383 -0400 EDT" level="info" msg="A group of walrus emerges from the ocean" animal="walrus" size=10
+time="2015-03-26T01:27:38-04:00" level=debug msg="Started observing beach" animal=walrus number=8
-time="2014-04-20 15:36:23.830584199 -0400 EDT" level="warning" msg="The group's number increased tremendously!" omg=true number=122
+time="2015-03-26T01:27:38-04:00" level=info msg="A group of walrus emerges from the ocean" animal=walrus size=10
-time="2014-04-20 15:36:23.830596521 -0400 EDT" level="info" msg="A giant walrus appears!" animal="walrus" size=10
+time="2015-03-26T01:27:38-04:00" level=warning msg="The group's number increased tremendously!" number=122 omg=true
-time="2014-04-20 15:36:23.830611837 -0400 EDT" level="info" msg="Tremendously sized cow enters the ocean." animal="walrus" size=9
+time="2015-03-26T01:27:38-04:00" level=debug msg="Temperature changes" temperature=-4
-time="2014-04-20 15:36:23.830626464 -0400 EDT" level="fatal" msg="The ice breaks!" omg=true number=100
+time="2015-03-26T01:27:38-04:00" level=panic msg="It's over 9000!" animal=orca size=9009
+time="2015-03-26T01:27:38-04:00" level=fatal msg="The ice breaks!" err=&{0x2082280c0 map[animal:orca size:9009] 2015-03-26 01:27:38.441574009 -0400 EDT panic It's over 9000!} number=100 omg=true
 ```
+To ensure this behaviour even if a TTY is attached, set your formatter as follows:
+
+```go
+	log.SetFormatter(&log.TextFormatter{
+		DisableColors: true,
+		FullTimestamp: true,
+	})
+```
+
+#### Logging Method Name
+
+If you wish to add the calling method as a field, instruct the logger via:
+```go
+log.SetReportCaller(true)
+```
+This adds the caller as 'method' like so:
+
+```json
+{"animal":"penguin","level":"fatal","method":"github.com/sirupsen/arcticcreatures.migrate","msg":"a penguin swims by",
+"time":"2014-03-10 19:57:38.562543129 -0400 EDT"}
+```
+
+```text
+time="2015-03-26T01:27:38-04:00" level=fatal method=github.com/sirupsen/arcticcreatures.migrate msg="a penguin swims by" animal=penguin
+```
+Note that this does add measurable overhead - the cost will depend on the version of Go, but is
+between 20 and 40% in recent tests with 1.6 and 1.7.  You can validate this in your
+environment via benchmarks: 
+```
+go test -bench=.*CallerTracing
+```
+
+
+#### Case-sensitivity
+
+The organization's name was changed to lower-case--and this will not be changed
+back. If you are getting import conflicts due to case sensitivity, please use
+the lower-case import: `git.internal/re/logrus`.
 
 #### Example
 
@@ -51,7 +119,7 @@ The simplest way to use Logrus is simply the package-level exported logger:
 package main
 
 import (
-  log "github.com/Sirupsen/logrus"
+  log "git.internal/re/logrus"
 )
 
 func main() {
@@ -62,7 +130,7 @@ func main() {
 ```
 
 Note that it's completely api-compatible with the stdlib logger, so you can
-replace your `log` imports everywhere with `log "github.com/Sirupsen/logrus"`
+replace your `log` imports everywhere with `log "git.internal/re/logrus"`
 and you'll now have the flexibility of Logrus. You can customize it all you
 want:
 
@@ -71,20 +139,16 @@ package main
 
 import (
   "os"
-  log "github.com/Sirupsen/logrus"
+  log "git.internal/re/logrus"
-  "github.com/Sirupsen/logrus/hooks/airbrake"
 )
 
 func init() {
   // Log as JSON instead of the default ASCII formatter.
   log.SetFormatter(&log.JSONFormatter{})
 
-  // Use the Airbrake hook to report errors that have Error severity or above to
+  // Output to stdout instead of the default stderr
-  // an exception tracker. You can create custom hooks, see the Hooks section.
+  // Can be any io.Writer, see below for File example
-  log.AddHook(&logrus_airbrake.AirbrakeHook{})
+  log.SetOutput(os.Stdout)
-
-  // Output to stderr instead of stdout, could also be a file.
-  log.SetOutput(os.Stderr)
 
   // Only log the warning severity or above.
   log.SetLevel(log.WarnLevel)
@@ -105,6 +169,16 @@ func main() {
     "omg":    true,
     "number": 100,
   }).Fatal("The ice breaks!")
+
+  // A common pattern is to re-use fields between logging statements by re-using
+  // the logrus.Entry returned from WithFields()
+  contextLogger := log.WithFields(log.Fields{
+    "common": "this is a common field",
+    "other": "I also should be logged always",
+  })
+
+  contextLogger.Info("I'll be logged with common and other field")
+  contextLogger.Info("Me too")
 }
 ```
 
@@ -115,7 +189,8 @@ application, you can also create an instance of the `logrus` Logger:
 package main
 
 import (
-  "github.com/Sirupsen/logrus"
+  "os"
+  "git.internal/re/logrus"
 )
 
 // Create a new instance of the logger. You can have any number of instances.
@@ -124,7 +199,15 @@ var log = logrus.New()
 func main() {
   // The API for setting attributes is a little different than the package level
   // exported logger. See Godoc.
-  log.Out = os.Stderr
+  log.Out = os.Stdout
+
+  // You could set this to any `io.Writer` such as a file
+  // file, err := os.OpenFile("logrus.log", os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0666)
+  // if err == nil {
+  //  log.Out = file
+  // } else {
+  //  log.Info("Failed to log to file, using default stderr")
+  // }
 
   log.WithFields(logrus.Fields{
     "animal": "walrus",
@@ -135,7 +218,7 @@ func main() {
 
 #### Fields
 
-Logrus encourages careful, structured logging though logging fields instead of
+Logrus encourages careful, structured logging through logging fields instead of
 long, unparseable error messages. For example, instead of: `log.Fatalf("Failed
 to send event %s to topic %s with key %d")`, you should log the much more
 discoverable:
@@ -157,60 +240,42 @@ In general, with Logrus using any of the `printf`-family functions should be
 seen as a hint you should add a field, however, you can still use the
 `printf`-family functions with Logrus.
 
+#### Default Fields
+
+Often it's helpful to have fields _always_ attached to log statements in an
+application or parts of one. For example, you may want to always log the
+`request_id` and `user_ip` in the context of a request. Instead of writing
+`log.WithFields(log.Fields{"request_id": request_id, "user_ip": user_ip})` on
+every line, you can create a `logrus.Entry` to pass around instead:
+
+```go
+requestLogger := log.WithFields(log.Fields{"request_id": request_id, "user_ip": user_ip})
+requestLogger.Info("something happened on that request") # will log request_id and user_ip
+requestLogger.Warn("something not great happened")
+```
+
 #### Hooks
 
 You can add hooks for logging levels. For example to send errors to an exception
 tracking service on `Error`, `Fatal` and `Panic`, info to StatsD or log to
 multiple places simultaneously, e.g. syslog.
 
-```go
+Logrus comes with [built-in hooks](hooks/). Add those, or your custom hook, in
-// Not the real implementation of the Airbrake hook. Just a simple sample.
+`init`:
-import (
-  log "github.com/Sirupsen/logrus"
-)
-
-func init() {
-  log.AddHook(new(AirbrakeHook))
-}
-
-type AirbrakeHook struct{}
-
-// `Fire()` takes the entry that the hook is fired for. `entry.Data[]` contains
-// the fields for the entry. See the Fields section of the README.
-func (hook *AirbrakeHook) Fire(entry *logrus.Entry) error {
-  err := airbrake.Notify(entry.Data["error"].(error))
-  if err != nil {
-    log.WithFields(log.Fields{
-      "source":   "airbrake",
-      "endpoint": airbrake.Endpoint,
-    }).Info("Failed to send error to Airbrake")
-  }
-
-  return nil
-}
-
-// `Levels()` returns a slice of `Levels` the hook is fired for.
-func (hook *AirbrakeHook) Levels() []log.Level {
-  return []log.Level{
-    log.ErrorLevel,
-    log.FatalLevel,
-    log.PanicLevel,
-  }
-}
-```
-
-Logrus comes with built-in hooks. Add those, or your custom hook, in `init`:
 
 ```go
 import (
-  log "github.com/Sirupsen/logrus"
+  log "git.internal/re/logrus"
-  "github.com/Sirupsen/logrus/hooks/airbrake"
+  "gopkg.in/gemnasium/logrus-airbrake-hook.v2" // the package is named "airbrake"
-  "github.com/Sirupsen/logrus/hooks/syslog"
+  logrus_syslog "git.internal/re/logrus/hooks/syslog"
   "log/syslog"
 )
 
 func init() {
-  log.AddHook(new(logrus_airbrake.AirbrakeHook))
+
+  // Use the Airbrake hook to report errors that have Error severity or above to
+  // an exception tracker. You can create custom hooks, see the Hooks section.
+  log.AddHook(airbrake.NewHook(123, "xyz", "production"))
 
   hook, err := logrus_syslog.NewSyslogHook("udp", "localhost:514", syslog.LOG_INFO, "")
   if err != nil {
@@ -220,29 +285,17 @@ func init() {
   }
 }
 ```
+Note: Syslog hook also support connecting to local syslog (Ex. "/dev/log" or "/var/run/syslog" or "/var/run/log"). For the detail, please check the [syslog hook README](hooks/syslog/README.md).
 
-* [`github.com/Sirupsen/logrus/hooks/airbrake`](https://github.com/Sirupsen/logrus/blob/master/hooks/airbrake/airbrake.go)
+A list of currently known service hooks can be found in this wiki [page](https://git.internal/re/logrus/wiki/Hooks)
-  Send errors to an exception tracking service compatible with the Airbrake API.
-  Uses [`airbrake-go`](https://github.com/tobi/airbrake-go) behind the scenes.
 
-* [`github.com/Sirupsen/logrus/hooks/papertrail`](https://github.com/Sirupsen/logrus/blob/master/hooks/papertrail/papertrail.go)
-  Send errors to the Papertrail hosted logging service via UDP.
-
-* [`github.com/Sirupsen/logrus/hooks/syslog`](https://github.com/Sirupsen/logrus/blob/master/hooks/syslog/syslog.go)
-  Send errors to remote syslog server.
-  Uses standard library `log/syslog` behind the scenes.
-
-* [`github.com/nubo/hiprus`](https://github.com/nubo/hiprus)
-  Send errors to a channel in hipchat.
-
-* [`github.com/sebest/logrusly`](https://github.com/sebest/logrusly)
-  Send logs to Loggly (https://www.loggly.com/)
 
 #### Level logging
 
-Logrus has six logging levels: Debug, Info, Warning, Error, Fatal and Panic.
+Logrus has seven logging levels: Trace, Debug, Info, Warning, Error, Fatal and Panic.
 
 ```go
+log.Trace("Something very low level.")
 log.Debug("Useful debugging information.")
 log.Info("Something noteworthy happened!")
 log.Warn("You should probably take a look at this.")
@@ -285,17 +338,17 @@ could do:
 
 ```go
 import (
-  log "github.com/Sirupsen/logrus"
+  log "git.internal/re/logrus"
 )
 
-init() {
+func init() {
   // do something here to set environment depending on an environment variable
   // or command-line flag
   if Environment == "production" {
-    log.SetFormatter(logrus.JSONFormatter)
+    log.SetFormatter(&log.JSONFormatter{})
   } else {
     // The TextFormatter is default, you don't actually have to do this.
-    log.SetFormatter(logrus.TextFormatter)
+    log.SetFormatter(&log.TextFormatter{})
   }
 }
 ```
@@ -312,12 +365,25 @@ The built-in logging formatters are:
   without colors.
   * *Note:* to force colored output when there is no TTY, set the `ForceColors`
     field to `true`.  To force no colored output even if there is a TTY  set the
-    `DisableColors` field to `true`
+    `DisableColors` field to `true`. For Windows, see
+    [github.com/mattn/go-colorable](https://github.com/mattn/go-colorable).
+  * When colors are enabled, levels are truncated to 4 characters by default. To disable
+    truncation set the `DisableLevelTruncation` field to `true`.
+  * When outputting to a TTY, it's often helpful to visually scan down a column where all the levels are the same width. Setting the `PadLevelText` field to `true` enables this behavior, by adding padding to the level text.
+  * All options are listed in the [generated docs](https://godoc.org/git.internal/re/logrus#TextFormatter).
 * `logrus.JSONFormatter`. Logs fields as JSON.
+  * All options are listed in the [generated docs](https://godoc.org/git.internal/re/logrus#JSONFormatter).
 
 Third party logging formatters:
 
-* [`zalgo`](https://github.com/aybabtme/logzalgo): invoking the P͉̫o̳̼̊w̖͈̰͎e̬͔̭͂r͚̼̹̲ ̫͓͉̳͈ō̠͕͖̚f̝͍̠ ͕̲̞͖͑Z̖̫̤̫ͪa͉̬͈̗l͖͎g̳̥o̰̥̅!̣͔̲̻͊̄ ̙̘̦̹̦.
+* [`FluentdFormatter`](https://github.com/joonix/log). Formats entries that can be parsed by Kubernetes and Google Container Engine.
+* [`GELF`](https://github.com/fabienm/go-logrus-formatters). Formats entries so they comply to Graylog's [GELF 1.1 specification](http://docs.graylog.org/en/2.4/pages/gelf.html).
+* [`logstash`](https://github.com/bshuster-repo/logrus-logstash-hook). Logs fields as [Logstash](http://logstash.net) Events.
+* [`prefixed`](https://github.com/x-cray/logrus-prefixed-formatter). Displays log entry source along with alternative layout.
+* [`zalgo`](https://github.com/aybabtme/logzalgo). Invoking the Power of Zalgo.
+* [`nested-logrus-formatter`](https://github.com/antonfisher/nested-logrus-formatter). Converts logrus fields to a nested structure.
+* [`powerful-logrus-formatter`](https://github.com/zput/zxcTool). get fileName, log's line number and the latest function's name when print log; Sava log to files.
+* [`caption-json-formatter`](https://github.com/nolleh/caption_json_formatter). logrus's message json formatter with human-readable caption added.
 
 You can define your formatter by implementing the `Formatter` interface,
 requiring a `Format` method. `Format` takes an `*Entry`. `entry.Data` is a
@@ -330,23 +396,118 @@ type MyJSONFormatter struct {
 
 log.SetFormatter(new(MyJSONFormatter))
 
-func (f *JSONFormatter) Format(entry *Entry) ([]byte, error) {
+func (f *MyJSONFormatter) Format(entry *Entry) ([]byte, error) {
   // Note this doesn't include Time, Level and Message which are available on
   // the Entry. Consult `godoc` on information about those fields or read the
   // source of the official loggers.
   serialized, err := json.Marshal(entry.Data)
     if err != nil {
-      return nil, fmt.Errorf("Failed to marshal fields to JSON, %v", err)
+      return nil, fmt.Errorf("Failed to marshal fields to JSON, %w", err)
     }
   return append(serialized, '\n'), nil
 }
 ```
 
+#### Logger as an `io.Writer`
+
+Logrus can be transformed into an `io.Writer`. That writer is the end of an `io.Pipe` and it is your responsibility to close it.
+
+```go
+w := logger.Writer()
+defer w.Close()
+
+srv := http.Server{
+    // create a stdlib log.Logger that writes to
+    // logrus.Logger.
+    ErrorLog: log.New(w, "", 0),
+}
+```
+
+Each line written to that writer will be printed the usual way, using formatters
+and hooks. The level for those entries is `info`.
+
+This means that we can override the standard library logger easily:
+
+```go
+logger := logrus.New()
+logger.Formatter = &logrus.JSONFormatter{}
+
+// Use logrus for standard log output
+// Note that `log` here references stdlib's log
+// Not logrus imported under the name `log`.
+log.SetOutput(logger.Writer())
+```
+
 #### Rotation
 
 Log rotation is not provided with Logrus. Log rotation should be done by an
-external program (like `logrotated(8)`) that can compress and delete old log
+external program (like `logrotate(8)`) that can compress and delete old log
 entries. It should not be a feature of the application-level logger.
 
+#### Tools
 
-[godoc]: https://godoc.org/github.com/Sirupsen/logrus
+| Tool | Description |
+| ---- | ----------- |
+|[Logrus Mate](https://github.com/gogap/logrus_mate)|Logrus mate is a tool for Logrus to manage loggers, you can initial logger's level, hook and formatter by config file, the logger will be generated with different configs in different environments.|
+|[Logrus Viper Helper](https://github.com/heirko/go-contrib/tree/master/logrusHelper)|An Helper around Logrus to wrap with spf13/Viper to load configuration with fangs! And to simplify Logrus configuration use some behavior of [Logrus Mate](https://github.com/gogap/logrus_mate). [sample](https://github.com/heirko/iris-contrib/blob/master/middleware/logrus-logger/example) |
+
+#### Testing
+
+Logrus has a built in facility for asserting the presence of log messages. This is implemented through the `test` hook and provides:
+
+* decorators for existing logger (`test.NewLocal` and `test.NewGlobal`) which basically just adds the `test` hook
+* a test logger (`test.NewNullLogger`) that just records log messages (and does not output any):
+
+```go
+import(
+  "git.internal/re/logrus"
+  "git.internal/re/logrus/hooks/test"
+  "github.com/stretchr/testify/assert"
+  "testing"
+)
+
+func TestSomething(t*testing.T){
+  logger, hook := test.NewNullLogger()
+  logger.Error("Helloerror")
+
+  assert.Equal(t, 1, len(hook.Entries))
+  assert.Equal(t, logrus.ErrorLevel, hook.LastEntry().Level)
+  assert.Equal(t, "Helloerror", hook.LastEntry().Message)
+
+  hook.Reset()
+  assert.Nil(t, hook.LastEntry())
+}
+```
+
+#### Fatal handlers
+
+Logrus can register one or more functions that will be called when any `fatal`
+level message is logged. The registered handlers will be executed before
+logrus performs an `os.Exit(1)`. This behavior may be helpful if callers need
+to gracefully shutdown. Unlike a `panic("Something went wrong...")` call which can be intercepted with a deferred `recover` a call to `os.Exit(1)` can not be intercepted.
+
+```
+...
+handler := func() {
+  // gracefully shutdown something...
+}
+logrus.RegisterExitHandler(handler)
+...
+```
+
+#### Thread safety
+
+By default, Logger is protected by a mutex for concurrent writes. The mutex is held when calling hooks and writing logs.
+If you are sure such locking is not needed, you can call logger.SetNoLock() to disable the locking.
+
+Situation when locking is not needed includes:
+
+* You have no hooks registered, or hooks calling is already thread-safe.
+
+* Writing to logger.Out is already thread-safe, for example:
+
+  1) logger.Out is protected by locks.
+
+  2) logger.Out is an os.File handler opened with `O_APPEND` flag, and every write is smaller than 4k. (This allows multi-thread/multi-process writing)
+
+     (Refer to http://www.notthewizard.com/2014/06/17/are-files-appends-really-atomic/)

alt_exit.go

@@ -0,0 +1,76 @@
+package logrus
+
+// The following code was sourced and modified from the
+// https://github.com/tebeka/atexit package governed by the following license:
+//
+// Copyright (c) 2012 Miki Tebeka <miki.tebeka@gmail.com>.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy of
+// this software and associated documentation files (the "Software"), to deal in
+// the Software without restriction, including without limitation the rights to
+// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+// the Software, and to permit persons to whom the Software is furnished to do so,
+// subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+// FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+// COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+// IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+import (
+	"fmt"
+	"os"
+)
+
+var handlers = []func(){}
+
+func runHandler(handler func()) {
+	defer func() {
+		if err := recover(); err != nil {
+			fmt.Fprintln(os.Stderr, "Error: Logrus exit handler error:", err)
+		}
+	}()
+
+	handler()
+}
+
+func runHandlers() {
+	for _, handler := range handlers {
+		runHandler(handler)
+	}
+}
+
+// Exit runs all the Logrus atexit handlers and then terminates the program using os.Exit(code)
+func Exit(code int) {
+	runHandlers()
+	os.Exit(code)
+}
+
+// RegisterExitHandler appends a Logrus Exit handler to the list of handlers,
+// call logrus.Exit to invoke all handlers. The handlers will also be invoked when
+// any Fatal log entry is made.
+//
+// This method is useful when a caller wishes to use logrus to log a fatal
+// message but also needs to gracefully shutdown. An example usecase could be
+// closing database connections, or sending a alert that the application is
+// closing.
+func RegisterExitHandler(handler func()) {
+	handlers = append(handlers, handler)
+}
+
+// DeferExitHandler prepends a Logrus Exit handler to the list of handlers,
+// call logrus.Exit to invoke all handlers. The handlers will also be invoked when
+// any Fatal log entry is made.
+//
+// This method is useful when a caller wishes to use logrus to log a fatal
+// message but also needs to gracefully shutdown. An example usecase could be
+// closing database connections, or sending a alert that the application is
+// closing.
+func DeferExitHandler(handler func()) {
+	handlers = append([]func(){handler}, handlers...)
+}

alt_exit_test.go

@@ -0,0 +1,151 @@
+package logrus
+
+import (
+	"io/ioutil"
+	"log"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestRegister(t *testing.T) {
+	current := len(handlers)
+
+	var results []string
+
+	h1 := func() { results = append(results, "first") }
+	h2 := func() { results = append(results, "second") }
+
+	RegisterExitHandler(h1)
+	RegisterExitHandler(h2)
+
+	if len(handlers) != current+2 {
+		t.Fatalf("expected %d handlers, got %d", current+2, len(handlers))
+	}
+
+	runHandlers()
+
+	if len(results) != 2 {
+		t.Fatalf("expected 2 handlers to be run, ran %d", len(results))
+	}
+
+	if results[0] != "first" {
+		t.Fatal("expected handler h1 to be run first, but it wasn't")
+	}
+
+	if results[1] != "second" {
+		t.Fatal("expected handler h2 to be run second, but it wasn't")
+	}
+}
+
+func TestDefer(t *testing.T) {
+	current := len(handlers)
+
+	var results []string
+
+	h1 := func() { results = append(results, "first") }
+	h2 := func() { results = append(results, "second") }
+
+	DeferExitHandler(h1)
+	DeferExitHandler(h2)
+
+	if len(handlers) != current+2 {
+		t.Fatalf("expected %d handlers, got %d", current+2, len(handlers))
+	}
+
+	runHandlers()
+
+	if len(results) != 2 {
+		t.Fatalf("expected 2 handlers to be run, ran %d", len(results))
+	}
+
+	if results[0] != "second" {
+		t.Fatal("expected handler h2 to be run first, but it wasn't")
+	}
+
+	if results[1] != "first" {
+		t.Fatal("expected handler h1 to be run second, but it wasn't")
+	}
+}
+
+func TestHandler(t *testing.T) {
+	testprog := testprogleader
+	testprog = append(testprog, getPackage()...)
+	testprog = append(testprog, testprogtrailer...)
+	tempDir, err := ioutil.TempDir("", "test_handler")
+	if err != nil {
+		log.Fatalf("can't create temp dir. %q", err)
+	}
+	defer os.RemoveAll(tempDir)
+
+	gofile := filepath.Join(tempDir, "gofile.go")
+	if err := ioutil.WriteFile(gofile, testprog, 0666); err != nil {
+		t.Fatalf("can't create go file. %q", err)
+	}
+
+	outfile := filepath.Join(tempDir, "outfile.out")
+	arg := time.Now().UTC().String()
+	err = exec.Command("go", "run", gofile, outfile, arg).Run()
+	if err == nil {
+		t.Fatalf("completed normally, should have failed")
+	}
+
+	data, err := ioutil.ReadFile(outfile)
+	if err != nil {
+		t.Fatalf("can't read output file %s. %q", outfile, err)
+	}
+
+	if string(data) != arg {
+		t.Fatalf("bad data. Expected %q, got %q", data, arg)
+	}
+}
+
+// getPackage returns the name of the current package, which makes running this
+// test in a fork simpler
+func getPackage() []byte {
+	pc, _, _, _ := runtime.Caller(0)
+	fullFuncName := runtime.FuncForPC(pc).Name()
+	idx := strings.LastIndex(fullFuncName, ".")
+	return []byte(fullFuncName[:idx]) // trim off function details
+}
+
+var testprogleader = []byte(`
+// Test program for atexit, gets output file and data as arguments and writes
+// data to output file in atexit handler.
+package main
+
+import (
+	"`)
+var testprogtrailer = []byte(
+	`"
+	"flag"
+	"fmt"
+	"io/ioutil"
+)
+
+var outfile = ""
+var data = ""
+
+func handler() {
+	ioutil.WriteFile(outfile, []byte(data), 0666)
+}
+
+func badHandler() {
+	n := 0
+	fmt.Println(1/n)
+}
+
+func main() {
+	flag.Parse()
+	outfile = flag.Arg(0)
+	data = flag.Arg(1)
+
+	logrus.RegisterExitHandler(handler)
+	logrus.RegisterExitHandler(badHandler)
+	logrus.Fatal("Bye bye")
+}
+`)

appveyor.yml

@@ -0,0 +1,14 @@
+version: "{build}"
+platform: x64
+clone_folder: c:\gopath\src\github.com\sirupsen\logrus
+environment:
+  GOPATH: c:\gopath
+branches:
+  only:
+    - master
+install:
+  - set PATH=%GOPATH%\bin;c:\go\bin;%PATH%
+  - go version
+build_script:
+  - go get -t
+  - go test

buffer_pool.go

@@ -0,0 +1,43 @@
+package logrus
+
+import (
+	"bytes"
+	"sync"
+)
+
+var (
+	bufferPool BufferPool
+)
+
+type BufferPool interface {
+	Put(*bytes.Buffer)
+	Get() *bytes.Buffer
+}
+
+type defaultPool struct {
+	pool *sync.Pool
+}
+
+func (p *defaultPool) Put(buf *bytes.Buffer) {
+	p.pool.Put(buf)
+}
+
+func (p *defaultPool) Get() *bytes.Buffer {
+	return p.pool.Get().(*bytes.Buffer)
+}
+
+// SetBufferPool allows to replace the default logrus buffer pool
+// to better meets the specific needs of an application.
+func SetBufferPool(bp BufferPool) {
+	bufferPool = bp
+}
+
+func init() {
+	SetBufferPool(&defaultPool{
+		pool: &sync.Pool{
+			New: func() interface{} {
+				return new(bytes.Buffer)
+			},
+		},
+	})
+}

ci/go.mod

@@ -0,0 +1,5 @@
+module git.internal/re/logrus/ci
+
+go 1.15
+
+require github.com/magefile/mage v1.11.0

ci/go.sum

@@ -0,0 +1,2 @@
+github.com/magefile/mage v1.11.0 h1:C/55Ywp9BpgVVclD3lRnSYCwXTYxmSppIgLeDYlNuls=
+github.com/magefile/mage v1.11.0/go.mod h1:z5UZb/iS3GoOSn0JgWuiw7dxlurVYTu+/jHXqQg881A=

ci/mage.go

@@ -0,0 +1,10 @@
+// +build ignore
+
+package main
+
+import (
+	"github.com/magefile/mage/mage"
+	"os"
+)
+
+func main() { os.Exit(mage.Main()) }

ci/magefile.go

@@ -0,0 +1,123 @@
+//go:build mage
+
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path"
+	"sort"
+
+	"github.com/magefile/mage/mg"
+	"github.com/magefile/mage/sh"
+)
+
+func intersect(a, b []string) []string {
+	sort.Strings(a)
+	sort.Strings(b)
+
+	res := make([]string, 0, func() int {
+		if len(a) < len(b) {
+			return len(a)
+		}
+		return len(b)
+	}())
+
+	for _, v := range a {
+		idx := sort.SearchStrings(b, v)
+		if idx < len(b) && b[idx] == v {
+			res = append(res, v)
+		}
+	}
+	return res
+}
+
+// getBuildMatrix returns the build matrix from the current version of the go compiler
+func getFullBuildMatrix() (map[string][]string, error) {
+	jsonData, err := sh.Output("go", "tool", "dist", "list", "-json")
+	if err != nil {
+		return nil, err
+	}
+	var data []struct {
+		Goos   string
+		Goarch string
+	}
+	if err := json.Unmarshal([]byte(jsonData), &data); err != nil {
+		return nil, err
+	}
+
+	matrix := map[string][]string{}
+	for _, v := range data {
+		if val, ok := matrix[v.Goos]; ok {
+			matrix[v.Goos] = append(val, v.Goarch)
+		} else {
+			matrix[v.Goos] = []string{v.Goarch}
+		}
+	}
+
+	return matrix, nil
+}
+
+func getBuildMatrix() (map[string][]string, error) {
+	minimalMatrix := map[string][]string{
+		"linux":   []string{"amd64"},
+		"darwin":  []string{"amd64", "arm64"},
+		"freebsd": []string{"amd64"},
+		"js":      []string{"wasm"},
+		"solaris": []string{"amd64"},
+		"windows": []string{"amd64", "arm64"},
+	}
+
+	fullMatrix, err := getFullBuildMatrix()
+	if err != nil {
+		return nil, err
+	}
+
+	for os, arches := range minimalMatrix {
+		if fullV, ok := fullMatrix[os]; !ok {
+			delete(minimalMatrix, os)
+		} else {
+			minimalMatrix[os] = intersect(arches, fullV)
+		}
+	}
+	return minimalMatrix, nil
+}
+
+func CrossBuild() error {
+	matrix, err := getBuildMatrix()
+	if err != nil {
+		return err
+	}
+
+	for os, arches := range matrix {
+		for _, arch := range arches {
+			env := map[string]string{
+				"GOOS":   os,
+				"GOARCH": arch,
+			}
+			if mg.Verbose() {
+				fmt.Printf("Building for GOOS=%s GOARCH=%s\n", os, arch)
+			}
+			if err := sh.RunWith(env, "go", "build", "./..."); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+func Lint() error {
+	gopath := os.Getenv("GOPATH")
+	if gopath == "" {
+		return fmt.Errorf("cannot retrieve GOPATH")
+	}
+
+	return sh.Run(path.Join(gopath, "bin", "golangci-lint"), "run", "./...")
+}
+
+// Run the test suite
+func Test() error {
+	return sh.RunWith(map[string]string{"GORACE": "halt_on_error=1"},
+		"go", "test", "-race", "-v", "./...")
+}

doc.go

@@ -0,0 +1,26 @@
+/*
+Package logrus is a structured logger for Go, completely API compatible with the standard library logger.
+
+The simplest way to use Logrus is simply the package-level exported logger:
+
+	package main
+
+	import (
+	  log "git.internal/re/logrus"
+	)
+
+	func main() {
+	  log.WithFields(log.Fields{
+	    "animal": "walrus",
+	    "number": 1,
+	    "size":   10,
+	  }).Info("A walrus appears")
+	}
+
+Output:
+
+	time="2015-09-07T08:48:33Z" level=info msg="A walrus appears" animal=walrus number=1 size=10
+
+For a full guide visit https://git.internal/re/logrus
+*/
+package logrus

entry.go

@@ -2,16 +2,45 @@ package logrus
 
 import (
 	"bytes"
+	"context"
 	"fmt"
-	"io"
 	"os"
+	"reflect"
+	"runtime"
+	"strings"
+	"sync"
 	"time"
 )
 
+var (
+
+	// qualified package name, cached at first use
+	logrusPackage string
+
+	// Positions in the call stack when tracing to report the calling method
+	minimumCallerDepth int
+
+	// Used for caller information initialisation
+	callerInitOnce sync.Once
+)
+
+const (
+	maximumCallerDepth int = 25
+	knownLogrusFrames  int = 4
+)
+
+func init() {
+	// start at the bottom of the stack before the package-name cache is primed
+	minimumCallerDepth = 1
+}
+
+// Defines the key when adding errors using WithError.
+var ErrorKey = "error"
+
 // An entry is the final or intermediate Logrus logging entry. It contains all
-// the fields passed with WithField{,s}. It's finally logged when Debug, Info,
+// the fields passed with WithField{,s}. It's finally logged when Trace, Debug,
-// Warn, Error, Fatal or Panic is called on it. These objects can be reused and
+// Info, Warn, Error, Fatal or Panic is called on it. These objects can be
-// passed around as much as you wish to avoid field duplication.
+// reused and passed around as much as you wish to avoid field duplication.
 type Entry struct {
 	Logger *Logger
 
@@ -21,36 +50,70 @@ type Entry struct {
 	// Time at which the log entry was created
 	Time time.Time
 
-	// Level the log entry was logged at: Debug, Info, Warn, Error, Fatal or Panic
+	// Level the log entry was logged at: Trace, Debug, Info, Warn, Error, Fatal or Panic
+	// This field will be set on entry firing and the value will be equal to the one in Logger struct field.
 	Level Level
 
-	// Message passed to Debug, Info, Warn, Error, Fatal or Panic
+	// Calling method, with package name
+	Caller *runtime.Frame
+
+	// Message passed to Trace, Debug, Info, Warn, Error, Fatal or Panic
 	Message string
+
+	// When formatter is called in entry.log(), a Buffer may be set to entry
+	Buffer *bytes.Buffer
+
+	// Contains the context set by the user. Useful for hook processing etc.
+	Context context.Context
+
+	// err may contain a field formatting error
+	err string
 }
 
 func NewEntry(logger *Logger) *Entry {
 	return &Entry{
 		Logger: logger,
-		// Default is three fields, give a little extra room
+		// Default is three fields, plus one optional.  Give a little extra room.
-		Data: make(Fields, 5),
+		Data: make(Fields, 6),
 	}
 }
 
-// Returns a reader for the entry, which is a proxy to the formatter.
+func (entry *Entry) Dup() *Entry {
-func (entry *Entry) Reader() (*bytes.Buffer, error) {
+	data := make(Fields, len(entry.Data))
-	serialized, err := entry.Logger.Formatter.Format(entry)
+	for k, v := range entry.Data {
-	return bytes.NewBuffer(serialized), err
+		data[k] = v
+	}
+	return &Entry{Logger: entry.Logger, Data: data, Time: entry.Time, Context: entry.Context, err: entry.err}
+}
+
+// Returns the bytes representation of this entry from the formatter.
+func (entry *Entry) Bytes() ([]byte, error) {
+	return entry.Logger.Formatter.Format(entry)
 }
 
 // Returns the string representation from the reader and ultimately the
 // formatter.
 func (entry *Entry) String() (string, error) {
-	reader, err := entry.Reader()
+	serialized, err := entry.Bytes()
 	if err != nil {
 		return "", err
 	}
+	str := string(serialized)
+	return str, nil
+}
 
-	return reader.String(), err
+// Add an error as single field (using the key defined in ErrorKey) to the Entry.
+func (entry *Entry) WithError(err error) *Entry {
+	return entry.WithField(ErrorKey, err)
+}
+
+// Add a context to the Entry.
+func (entry *Entry) WithContext(ctx context.Context) *Entry {
+	dataCopy := make(Fields, len(entry.Data))
+	for k, v := range entry.Data {
+		dataCopy[k] = v
+	}
+	return &Entry{Logger: entry.Logger, Data: dataCopy, Time: entry.Time, err: entry.err, Context: ctx}
 }
 
 // Add a single field to the Entry.
@@ -60,54 +123,194 @@ func (entry *Entry) WithField(key string, value interface{}) *Entry {
 
 // Add a map of fields to the Entry.
 func (entry *Entry) WithFields(fields Fields) *Entry {
-	data := Fields{}
+	data := make(Fields, len(entry.Data)+len(fields))
 	for k, v := range entry.Data {
 		data[k] = v
 	}
+	fieldErr := entry.err
 	for k, v := range fields {
-		data[k] = v
+		isErrField := false
+		if t := reflect.TypeOf(v); t != nil {
+			switch {
+			case t.Kind() == reflect.Func, t.Kind() == reflect.Ptr && t.Elem().Kind() == reflect.Func:
+				isErrField = true
+			}
+		}
+		if isErrField {
+			tmp := fmt.Sprintf("can not add field %q", k)
+			if fieldErr != "" {
+				fieldErr = entry.err + ", " + tmp
+			} else {
+				fieldErr = tmp
+			}
+		} else {
+			data[k] = v
+		}
 	}
-	return &Entry{Logger: entry.Logger, Data: data}
+	return &Entry{Logger: entry.Logger, Data: data, Time: entry.Time, err: fieldErr, Context: entry.Context}
+}
+
+// Overrides the time of the Entry.
+func (entry *Entry) WithTime(t time.Time) *Entry {
+	dataCopy := make(Fields, len(entry.Data))
+	for k, v := range entry.Data {
+		dataCopy[k] = v
+	}
+	return &Entry{Logger: entry.Logger, Data: dataCopy, Time: t, err: entry.err, Context: entry.Context}
+}
+
+// getPackageName reduces a fully qualified function name to the package name
+// There really ought to be to be a better way...
+func getPackageName(f string) string {
+	for {
+		lastPeriod := strings.LastIndex(f, ".")
+		lastSlash := strings.LastIndex(f, "/")
+		if lastPeriod > lastSlash {
+			f = f[:lastPeriod]
+		} else {
+			break
+		}
+	}
+
+	return f
+}
+
+// getCaller retrieves the name of the first non-logrus calling function
+func getCaller() *runtime.Frame {
+	// cache this package's fully-qualified name
+	callerInitOnce.Do(func() {
+		pcs := make([]uintptr, maximumCallerDepth)
+		_ = runtime.Callers(0, pcs)
+
+		// dynamic get the package name and the minimum caller depth
+		for i := 0; i < maximumCallerDepth; i++ {
+			funcName := runtime.FuncForPC(pcs[i]).Name()
+			if strings.Contains(funcName, "getCaller") {
+				logrusPackage = getPackageName(funcName)
+				break
+			}
+		}
+
+		minimumCallerDepth = knownLogrusFrames
+	})
+
+	// Restrict the lookback frames to avoid runaway lookups
+	pcs := make([]uintptr, maximumCallerDepth)
+	depth := runtime.Callers(minimumCallerDepth, pcs)
+	frames := runtime.CallersFrames(pcs[:depth])
+
+	for f, again := frames.Next(); again; f, again = frames.Next() {
+		pkg := getPackageName(f.Function)
+
+		// If the caller isn't part of this package, we're done
+		if pkg != logrusPackage {
+			return &f //nolint:scopelint
+		}
+	}
+
+	// if we got here, we failed to find the caller's context
+	return nil
+}
+
+func (entry Entry) HasCaller() (has bool) {
+	return entry.Logger != nil &&
+		entry.Logger.ReportCaller &&
+		entry.Caller != nil
 }
 
 func (entry *Entry) log(level Level, msg string) {
-	entry.Time = time.Now()
+	var buffer *bytes.Buffer
-	entry.Level = level
-	entry.Message = msg
 
-	if err := entry.Logger.Hooks.Fire(level, entry); err != nil {
+	newEntry := entry.Dup()
-		entry.Logger.mu.Lock()
+
-		fmt.Fprintf(os.Stderr, "Failed to fire hook: %v\n", err)
+	if newEntry.Time.IsZero() {
-		entry.Logger.mu.Unlock()
+		newEntry.Time = time.Now()
 	}
 
-	reader, err := entry.Reader()
+	newEntry.Level = level
-	if err != nil {
+	newEntry.Message = msg
-		entry.Logger.mu.Lock()
+
-		fmt.Fprintf(os.Stderr, "Failed to obtain reader, %v\n", err)
+	newEntry.Logger.mu.Lock()
-		entry.Logger.mu.Unlock()
+	reportCaller := newEntry.Logger.ReportCaller
+	bufPool := newEntry.getBufferPool()
+	newEntry.Logger.mu.Unlock()
+
+	if reportCaller {
+		newEntry.Caller = getCaller()
 	}
 
-	entry.Logger.mu.Lock()
+	newEntry.fireHooks()
-	defer entry.Logger.mu.Unlock()
+	buffer = bufPool.Get()
+	defer func() {
+		newEntry.Buffer = nil
+		buffer.Reset()
+		bufPool.Put(buffer)
+	}()
+	buffer.Reset()
+	newEntry.Buffer = buffer
 
-	_, err = io.Copy(entry.Logger.Out, reader)
+	newEntry.write()
-	if err != nil {
+
-		fmt.Fprintf(os.Stderr, "Failed to write to log, %v\n", err)
+	newEntry.Buffer = nil
-	}
 
 	// To avoid Entry#log() returning a value that only would make sense for
 	// panic() to use in Entry#Panic(), we avoid the allocation by checking
 	// directly here.
 	if level <= PanicLevel {
-		panic(entry)
+		panic(newEntry)
 	}
 }
 
-func (entry *Entry) Debug(args ...interface{}) {
+func (entry *Entry) getBufferPool() (pool BufferPool) {
-	if entry.Logger.Level >= DebugLevel {
+	if entry.Logger.BufferPool != nil {
-		entry.log(DebugLevel, fmt.Sprint(args...))
+		return entry.Logger.BufferPool
 	}
+	return bufferPool
+}
+
+func (entry *Entry) fireHooks() {
+	var tmpHooks LevelHooks
+	entry.Logger.mu.Lock()
+	tmpHooks = make(LevelHooks, len(entry.Logger.Hooks))
+	for k, v := range entry.Logger.Hooks {
+		tmpHooks[k] = v
+	}
+	entry.Logger.mu.Unlock()
+
+	err := tmpHooks.Fire(entry.Level, entry)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to fire hook: %v\n", err)
+	}
+}
+
+func (entry *Entry) write() {
+	entry.Logger.mu.Lock()
+	defer entry.Logger.mu.Unlock()
+	serialized, err := entry.Logger.Formatter.Format(entry)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to obtain reader, %v\n", err)
+		return
+	}
+	if _, err := entry.Logger.Out.Write(serialized); err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to write to log, %v\n", err)
+	}
+}
+
+// Log will log a message at the level given as parameter.
+// Warning: using Log at Panic or Fatal level will not respectively Panic nor Exit.
+// For this behaviour Entry.Panic or Entry.Fatal should be used instead.
+func (entry *Entry) Log(level Level, args ...interface{}) {
+	if entry.Logger.IsLevelEnabled(level) {
+		entry.log(level, fmt.Sprint(args...))
+	}
+}
+
+func (entry *Entry) Trace(args ...interface{}) {
+	entry.Log(TraceLevel, args...)
+}
+
+func (entry *Entry) Debug(args ...interface{}) {
+	entry.Log(DebugLevel, args...)
 }
 
 func (entry *Entry) Print(args ...interface{}) {
@@ -115,49 +318,48 @@ func (entry *Entry) Print(args ...interface{}) {
 }
 
 func (entry *Entry) Info(args ...interface{}) {
-	if entry.Logger.Level >= InfoLevel {
+	entry.Log(InfoLevel, args...)
-		entry.log(InfoLevel, fmt.Sprint(args...))
-	}
 }
 
 func (entry *Entry) Warn(args ...interface{}) {
-	if entry.Logger.Level >= WarnLevel {
+	entry.Log(WarnLevel, args...)
-		entry.log(WarnLevel, fmt.Sprint(args...))
+}
-	}
+
+func (entry *Entry) Warning(args ...interface{}) {
+	entry.Warn(args...)
 }
 
 func (entry *Entry) Error(args ...interface{}) {
-	if entry.Logger.Level >= ErrorLevel {
+	entry.Log(ErrorLevel, args...)
-		entry.log(ErrorLevel, fmt.Sprint(args...))
-	}
 }
 
 func (entry *Entry) Fatal(args ...interface{}) {
-	if entry.Logger.Level >= FatalLevel {
+	entry.Log(FatalLevel, args...)
-		entry.log(FatalLevel, fmt.Sprint(args...))
+	entry.Logger.Exit(1)
-	}
-	os.Exit(1)
 }
 
 func (entry *Entry) Panic(args ...interface{}) {
-	if entry.Logger.Level >= PanicLevel {
+	entry.Log(PanicLevel, args...)
-		entry.log(PanicLevel, fmt.Sprint(args...))
-	}
-	panic(fmt.Sprint(args...))
 }
 
 // Entry Printf family functions
 
-func (entry *Entry) Debugf(format string, args ...interface{}) {
+func (entry *Entry) Logf(level Level, format string, args ...interface{}) {
-	if entry.Logger.Level >= DebugLevel {
+	if entry.Logger.IsLevelEnabled(level) {
-		entry.Debug(fmt.Sprintf(format, args...))
+		entry.Log(level, fmt.Sprintf(format, args...))
 	}
 }
 
+func (entry *Entry) Tracef(format string, args ...interface{}) {
+	entry.Logf(TraceLevel, format, args...)
+}
+
+func (entry *Entry) Debugf(format string, args ...interface{}) {
+	entry.Logf(DebugLevel, format, args...)
+}
+
 func (entry *Entry) Infof(format string, args ...interface{}) {
-	if entry.Logger.Level >= InfoLevel {
+	entry.Logf(InfoLevel, format, args...)
-		entry.Info(fmt.Sprintf(format, args...))
-	}
 }
 
 func (entry *Entry) Printf(format string, args ...interface{}) {
@@ -165,9 +367,7 @@ func (entry *Entry) Printf(format string, args ...interface{}) {
 }
 
 func (entry *Entry) Warnf(format string, args ...interface{}) {
-	if entry.Logger.Level >= WarnLevel {
+	entry.Logf(WarnLevel, format, args...)
-		entry.Warn(fmt.Sprintf(format, args...))
-	}
 }
 
 func (entry *Entry) Warningf(format string, args ...interface{}) {
@@ -175,35 +375,36 @@ func (entry *Entry) Warningf(format string, args ...interface{}) {
 }
 
 func (entry *Entry) Errorf(format string, args ...interface{}) {
-	if entry.Logger.Level >= ErrorLevel {
+	entry.Logf(ErrorLevel, format, args...)
-		entry.Error(fmt.Sprintf(format, args...))
-	}
 }
 
 func (entry *Entry) Fatalf(format string, args ...interface{}) {
-	if entry.Logger.Level >= FatalLevel {
+	entry.Logf(FatalLevel, format, args...)
-		entry.Fatal(fmt.Sprintf(format, args...))
+	entry.Logger.Exit(1)
-	}
 }
 
 func (entry *Entry) Panicf(format string, args ...interface{}) {
-	if entry.Logger.Level >= PanicLevel {
+	entry.Logf(PanicLevel, format, args...)
-		entry.Panic(fmt.Sprintf(format, args...))
-	}
 }
 
 // Entry Println family functions
 
-func (entry *Entry) Debugln(args ...interface{}) {
+func (entry *Entry) Logln(level Level, args ...interface{}) {
-	if entry.Logger.Level >= DebugLevel {
+	if entry.Logger.IsLevelEnabled(level) {
-		entry.Debug(entry.sprintlnn(args...))
+		entry.Log(level, entry.sprintlnn(args...))
 	}
 }
 
+func (entry *Entry) Traceln(args ...interface{}) {
+	entry.Logln(TraceLevel, args...)
+}
+
+func (entry *Entry) Debugln(args ...interface{}) {
+	entry.Logln(DebugLevel, args...)
+}
+
 func (entry *Entry) Infoln(args ...interface{}) {
-	if entry.Logger.Level >= InfoLevel {
+	entry.Logln(InfoLevel, args...)
-		entry.Info(entry.sprintlnn(args...))
-	}
 }
 
 func (entry *Entry) Println(args ...interface{}) {
@@ -211,9 +412,7 @@ func (entry *Entry) Println(args ...interface{}) {
 }
 
 func (entry *Entry) Warnln(args ...interface{}) {
-	if entry.Logger.Level >= WarnLevel {
+	entry.Logln(WarnLevel, args...)
-		entry.Warn(entry.sprintlnn(args...))
-	}
 }
 
 func (entry *Entry) Warningln(args ...interface{}) {
@@ -221,21 +420,16 @@ func (entry *Entry) Warningln(args ...interface{}) {
 }
 
 func (entry *Entry) Errorln(args ...interface{}) {
-	if entry.Logger.Level >= ErrorLevel {
+	entry.Logln(ErrorLevel, args...)
-		entry.Error(entry.sprintlnn(args...))
-	}
 }
 
 func (entry *Entry) Fatalln(args ...interface{}) {
-	if entry.Logger.Level >= FatalLevel {
+	entry.Logln(FatalLevel, args...)
-		entry.Fatal(entry.sprintlnn(args...))
+	entry.Logger.Exit(1)
-	}
 }
 
 func (entry *Entry) Panicln(args ...interface{}) {
-	if entry.Logger.Level >= PanicLevel {
+	entry.Logln(PanicLevel, args...)
-		entry.Panic(entry.sprintlnn(args...))
-	}
 }
 
 // Sprintlnn => Sprint no newline. This is to get the behavior of how

entry_test.go

@@ -2,12 +2,127 @@ package logrus
 
 import (
 	"bytes"
+	"context"
 	"fmt"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 )
 
+func TestEntryWithError(t *testing.T) {
+
+	assert := assert.New(t)
+
+	defer func() {
+		ErrorKey = "error"
+	}()
+
+	err := fmt.Errorf("kaboom at layer %d", 4711)
+
+	assert.Equal(err, WithError(err).Data["error"])
+
+	logger := New()
+	logger.Out = &bytes.Buffer{}
+	entry := NewEntry(logger)
+
+	assert.Equal(err, entry.WithError(err).Data["error"])
+
+	ErrorKey = "err"
+
+	assert.Equal(err, entry.WithError(err).Data["err"])
+
+}
+
+func TestEntryWithContext(t *testing.T) {
+	assert := assert.New(t)
+	ctx := context.WithValue(context.Background(), "foo", "bar")
+
+	assert.Equal(ctx, WithContext(ctx).Context)
+
+	logger := New()
+	logger.Out = &bytes.Buffer{}
+	entry := NewEntry(logger)
+
+	assert.Equal(ctx, entry.WithContext(ctx).Context)
+}
+
+func TestEntryWithContextCopiesData(t *testing.T) {
+	assert := assert.New(t)
+
+	// Initialize a parent Entry object with a key/value set in its Data map
+	logger := New()
+	logger.Out = &bytes.Buffer{}
+	parentEntry := NewEntry(logger).WithField("parentKey", "parentValue")
+
+	// Create two children Entry objects from the parent in different contexts
+	ctx1 := context.WithValue(context.Background(), "foo", "bar")
+	childEntry1 := parentEntry.WithContext(ctx1)
+	assert.Equal(ctx1, childEntry1.Context)
+
+	ctx2 := context.WithValue(context.Background(), "bar", "baz")
+	childEntry2 := parentEntry.WithContext(ctx2)
+	assert.Equal(ctx2, childEntry2.Context)
+	assert.NotEqual(ctx1, ctx2)
+
+	// Ensure that data set in the parent Entry are preserved to both children
+	assert.Equal("parentValue", childEntry1.Data["parentKey"])
+	assert.Equal("parentValue", childEntry2.Data["parentKey"])
+
+	// Modify data stored in the child entry
+	childEntry1.Data["childKey"] = "childValue"
+
+	// Verify that data is successfully stored in the child it was set on
+	val, exists := childEntry1.Data["childKey"]
+	assert.True(exists)
+	assert.Equal("childValue", val)
+
+	// Verify that the data change to child 1 has not affected its sibling
+	val, exists = childEntry2.Data["childKey"]
+	assert.False(exists)
+	assert.Empty(val)
+
+	// Verify that the data change to child 1 has not affected its parent
+	val, exists = parentEntry.Data["childKey"]
+	assert.False(exists)
+	assert.Empty(val)
+}
+
+func TestEntryWithTimeCopiesData(t *testing.T) {
+	assert := assert.New(t)
+
+	// Initialize a parent Entry object with a key/value set in its Data map
+	logger := New()
+	logger.Out = &bytes.Buffer{}
+	parentEntry := NewEntry(logger).WithField("parentKey", "parentValue")
+
+	// Create two children Entry objects from the parent with two different times
+	childEntry1 := parentEntry.WithTime(time.Now().AddDate(0, 0, 1))
+	childEntry2 := parentEntry.WithTime(time.Now().AddDate(0, 0, 2))
+
+	// Ensure that data set in the parent Entry are preserved to both children
+	assert.Equal("parentValue", childEntry1.Data["parentKey"])
+	assert.Equal("parentValue", childEntry2.Data["parentKey"])
+
+	// Modify data stored in the child entry
+	childEntry1.Data["childKey"] = "childValue"
+
+	// Verify that data is successfully stored in the child it was set on
+	val, exists := childEntry1.Data["childKey"]
+	assert.True(exists)
+	assert.Equal("childValue", val)
+
+	// Verify that the data change to child 1 has not affected its sibling
+	val, exists = childEntry2.Data["childKey"]
+	assert.False(exists)
+	assert.Empty(val)
+
+	// Verify that the data change to child 1 has not affected its parent
+	val, exists = parentEntry.Data["childKey"]
+	assert.False(exists)
+	assert.Empty(val)
+}
+
 func TestEntryPanicln(t *testing.T) {
 	errBoom := fmt.Errorf("boom time")
 
@@ -51,3 +166,136 @@ func TestEntryPanicf(t *testing.T) {
 	entry := NewEntry(logger)
 	entry.WithField("err", errBoom).Panicf("kaboom %v", true)
 }
+
+func TestEntryPanic(t *testing.T) {
+	errBoom := fmt.Errorf("boom again")
+
+	defer func() {
+		p := recover()
+		assert.NotNil(t, p)
+
+		switch pVal := p.(type) {
+		case *Entry:
+			assert.Equal(t, "kaboom", pVal.Message)
+			assert.Equal(t, errBoom, pVal.Data["err"])
+		default:
+			t.Fatalf("want type *Entry, got %T: %#v", pVal, pVal)
+		}
+	}()
+
+	logger := New()
+	logger.Out = &bytes.Buffer{}
+	entry := NewEntry(logger)
+	entry.WithField("err", errBoom).Panic("kaboom")
+}
+
+const (
+	badMessage   = "this is going to panic"
+	panicMessage = "this is broken"
+)
+
+type panickyHook struct{}
+
+func (p *panickyHook) Levels() []Level {
+	return []Level{InfoLevel}
+}
+
+func (p *panickyHook) Fire(entry *Entry) error {
+	if entry.Message == badMessage {
+		panic(panicMessage)
+	}
+
+	return nil
+}
+
+func TestEntryHooksPanic(t *testing.T) {
+	logger := New()
+	logger.Out = &bytes.Buffer{}
+	logger.Level = InfoLevel
+	logger.Hooks.Add(&panickyHook{})
+
+	defer func() {
+		p := recover()
+		assert.NotNil(t, p)
+		assert.Equal(t, panicMessage, p)
+
+		entry := NewEntry(logger)
+		entry.Info("another message")
+	}()
+
+	entry := NewEntry(logger)
+	entry.Info(badMessage)
+}
+
+func TestEntryWithIncorrectField(t *testing.T) {
+	assert := assert.New(t)
+
+	fn := func() {}
+
+	e := Entry{Logger: New()}
+	eWithFunc := e.WithFields(Fields{"func": fn})
+	eWithFuncPtr := e.WithFields(Fields{"funcPtr": &fn})
+
+	assert.Equal(eWithFunc.err, `can not add field "func"`)
+	assert.Equal(eWithFuncPtr.err, `can not add field "funcPtr"`)
+
+	eWithFunc = eWithFunc.WithField("not_a_func", "it is a string")
+	eWithFuncPtr = eWithFuncPtr.WithField("not_a_func", "it is a string")
+
+	assert.Equal(eWithFunc.err, `can not add field "func"`)
+	assert.Equal(eWithFuncPtr.err, `can not add field "funcPtr"`)
+
+	eWithFunc = eWithFunc.WithTime(time.Now())
+	eWithFuncPtr = eWithFuncPtr.WithTime(time.Now())
+
+	assert.Equal(eWithFunc.err, `can not add field "func"`)
+	assert.Equal(eWithFuncPtr.err, `can not add field "funcPtr"`)
+}
+
+func TestEntryLogfLevel(t *testing.T) {
+	logger := New()
+	buffer := &bytes.Buffer{}
+	logger.Out = buffer
+	logger.SetLevel(InfoLevel)
+	entry := NewEntry(logger)
+
+	entry.Logf(DebugLevel, "%s", "debug")
+	assert.NotContains(t, buffer.String(), "debug")
+
+	entry.Logf(WarnLevel, "%s", "warn")
+	assert.Contains(t, buffer.String(), "warn")
+}
+
+func TestEntryReportCallerRace(t *testing.T) {
+	logger := New()
+	entry := NewEntry(logger)
+
+	// logging before SetReportCaller has the highest chance of causing a race condition
+	// to be detected, but doing it twice just to increase the likelyhood of detecting the race
+	go func() {
+		entry.Info("should not race")
+	}()
+	go func() {
+		logger.SetReportCaller(true)
+	}()
+	go func() {
+		entry.Info("should not race")
+	}()
+}
+
+func TestEntryFormatterRace(t *testing.T) {
+	logger := New()
+	entry := NewEntry(logger)
+
+	// logging before SetReportCaller has the highest chance of causing a race condition
+	// to be detected, but doing it twice just to increase the likelyhood of detecting the race
+	go func() {
+		entry.Info("should not race")
+	}()
+	go func() {
+		logger.SetFormatter(&TextFormatter{})
+	}()
+	go func() {
+		entry.Info("should not race")
+	}()
+}

example_basic_test.go

@@ -0,0 +1,77 @@
+package logrus_test
+
+import (
+	"os"
+
+	"git.internal/re/logrus"
+)
+
+func Example_basic() {
+	log := logrus.New()
+	log.Formatter = new(logrus.JSONFormatter)
+	log.Formatter = new(logrus.TextFormatter)                     // default
+	log.Formatter.(*logrus.TextFormatter).DisableColors = true    // remove colors
+	log.Formatter.(*logrus.TextFormatter).DisableTimestamp = true // remove timestamp from test output
+	log.Level = logrus.TraceLevel
+	log.Out = os.Stdout
+
+	// file, err := os.OpenFile("logrus.log", os.O_CREATE|os.O_WRONLY, 0666)
+	// if err == nil {
+	// 	log.Out = file
+	// } else {
+	// 	log.Info("Failed to log to file, using default stderr")
+	// }
+
+	defer func() {
+		err := recover()
+		if err != nil {
+			entry := err.(*logrus.Entry)
+			log.WithFields(logrus.Fields{
+				"omg":         true,
+				"err_animal":  entry.Data["animal"],
+				"err_size":    entry.Data["size"],
+				"err_level":   entry.Level,
+				"err_message": entry.Message,
+				"number":      100,
+			}).Error("The ice breaks!") // or use Fatal() to force the process to exit with a nonzero code
+		}
+	}()
+
+	log.WithFields(logrus.Fields{
+		"animal": "walrus",
+		"number": 0,
+	}).Trace("Went to the beach")
+
+	log.WithFields(logrus.Fields{
+		"animal": "walrus",
+		"number": 8,
+	}).Debug("Started observing beach")
+
+	log.WithFields(logrus.Fields{
+		"animal": "walrus",
+		"size":   10,
+	}).Info("A group of walrus emerges from the ocean")
+
+	log.WithFields(logrus.Fields{
+		"omg":    true,
+		"number": 122,
+	}).Warn("The group's number increased tremendously!")
+
+	log.WithFields(logrus.Fields{
+		"temperature": -4,
+	}).Debug("Temperature changes")
+
+	log.WithFields(logrus.Fields{
+		"animal": "orca",
+		"size":   9009,
+	}).Panic("It's over 9000!")
+
+	// Output:
+	// level=trace msg="Went to the beach" animal=walrus number=0
+	// level=debug msg="Started observing beach" animal=walrus number=8
+	// level=info msg="A group of walrus emerges from the ocean" animal=walrus size=10
+	// level=warning msg="The group's number increased tremendously!" number=122 omg=true
+	// level=debug msg="Temperature changes" temperature=-4
+	// level=panic msg="It's over 9000!" animal=orca size=9009
+	// level=error msg="The ice breaks!" err_animal=orca err_level=panic err_message="It's over 9000!" err_size=9009 number=100 omg=true
+}

example_custom_caller_test.go

@@ -0,0 +1,28 @@
+package logrus_test
+
+import (
+	"os"
+	"path"
+	"runtime"
+	"strings"
+
+	"git.internal/re/logrus"
+)
+
+func ExampleJSONFormatter_CallerPrettyfier() {
+	l := logrus.New()
+	l.SetReportCaller(true)
+	l.Out = os.Stdout
+	l.Formatter = &logrus.JSONFormatter{
+		DisableTimestamp: true,
+		CallerPrettyfier: func(f *runtime.Frame) (string, string) {
+			s := strings.Split(f.Function, ".")
+			funcname := s[len(s)-1]
+			_, filename := path.Split(f.File)
+			return funcname, filename
+		},
+	}
+	l.Info("example of custom format caller")
+	// Output:
+	// {"file":"example_custom_caller_test.go","func":"ExampleJSONFormatter_CallerPrettyfier","level":"info","msg":"example of custom format caller"}
+}

example_default_field_value_test.go

@@ -0,0 +1,31 @@
+package logrus_test
+
+import (
+	"os"
+
+	"git.internal/re/logrus"
+)
+
+type DefaultFieldHook struct {
+	GetValue func() string
+}
+
+func (h *DefaultFieldHook) Levels() []logrus.Level {
+	return logrus.AllLevels
+}
+
+func (h *DefaultFieldHook) Fire(e *logrus.Entry) error {
+	e.Data["aDefaultField"] = h.GetValue()
+	return nil
+}
+
+func ExampleDefaultFieldHook() {
+	l := logrus.New()
+	l.Out = os.Stdout
+	l.Formatter = &logrus.TextFormatter{DisableTimestamp: true, DisableColors: true}
+
+	l.AddHook(&DefaultFieldHook{GetValue: func() string { return "with its default value" }})
+	l.Info("first log")
+	// Output:
+	// level=info msg="first log" aDefaultField="with its default value"
+}

example_function_test.go

@@ -0,0 +1,31 @@
+package logrus_test
+
+import (
+	"testing"
+
+	log "git.internal/re/logrus"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestLogger_LogFn(t *testing.T) {
+	log.SetFormatter(&log.JSONFormatter{})
+	log.SetLevel(log.WarnLevel)
+
+	notCalled := 0
+	log.InfoFn(func() []interface{} {
+		notCalled++
+		return []interface{}{
+			"Hello",
+		}
+	})
+	assert.Equal(t, 0, notCalled)
+
+	called := 0
+	log.ErrorFn(func() []interface{} {
+		called++
+		return []interface{}{
+			"Oopsi",
+		}
+	})
+	assert.Equal(t, 1, called)
+}

example_global_hook_test.go

@@ -0,0 +1,34 @@
+package logrus_test
+
+import (
+	"os"
+
+	"git.internal/re/logrus"
+)
+
+var mystring string
+
+type GlobalHook struct{}
+
+func (h *GlobalHook) Levels() []logrus.Level {
+	return logrus.AllLevels
+}
+
+func (h *GlobalHook) Fire(e *logrus.Entry) error {
+	e.Data["mystring"] = mystring
+	return nil
+}
+
+func ExampleGlobalHook() {
+	l := logrus.New()
+	l.Out = os.Stdout
+	l.Formatter = &logrus.TextFormatter{DisableTimestamp: true, DisableColors: true}
+	l.AddHook(&GlobalHook{})
+	mystring = "first value"
+	l.Info("first log")
+	mystring = "another value"
+	l.Info("second log")
+	// Output:
+	// level=info msg="first log" mystring="first value"
+	// level=info msg="second log" mystring="another value"
+}

example_hook_test.go

@@ -0,0 +1,44 @@
+//go:build !windows
+// +build !windows
+
+package logrus_test
+
+import (
+	"log/syslog"
+	"os"
+
+	"git.internal/re/logrus"
+	slhooks "git.internal/re/logrus/hooks/syslog"
+)
+
+// An example on how to use a hook
+func Example_hook() {
+	log := logrus.New()
+	log.Formatter = new(logrus.TextFormatter)                     // default
+	log.Formatter.(*logrus.TextFormatter).DisableColors = true    // remove colors
+	log.Formatter.(*logrus.TextFormatter).DisableTimestamp = true // remove timestamp from test output
+	if sl, err := slhooks.NewSyslogHook("udp", "localhost:514", syslog.LOG_INFO, ""); err == nil {
+		log.Hooks.Add(sl)
+	}
+	log.Out = os.Stdout
+
+	log.WithFields(logrus.Fields{
+		"animal": "walrus",
+		"size":   10,
+	}).Info("A group of walrus emerges from the ocean")
+
+	log.WithFields(logrus.Fields{
+		"omg":    true,
+		"number": 122,
+	}).Warn("The group's number increased tremendously!")
+
+	log.WithFields(logrus.Fields{
+		"omg":    true,
+		"number": 100,
+	}).Error("The ice breaks!")
+
+	// Output:
+	// level=info msg="A group of walrus emerges from the ocean" animal=walrus size=10
+	// level=warning msg="The group's number increased tremendously!" number=122 omg=true
+	// level=error msg="The ice breaks!" number=100 omg=true
+}

examples/basic/basic.go

@@ -1,40 +0,0 @@
-package main
-
-import (
-	"github.com/Sirupsen/logrus"
-)
-
-var log = logrus.New()
-
-func init() {
-	log.Formatter = new(logrus.JSONFormatter)
-	log.Formatter = new(logrus.TextFormatter) // default
-}
-
-func main() {
-	defer func() {
-		err := recover()
-		if err != nil {
-			log.WithFields(logrus.Fields{
-				"omg":    true,
-				"err":    err,
-				"number": 100,
-			}).Fatal("The ice breaks!")
-		}
-	}()
-
-	log.WithFields(logrus.Fields{
-		"animal": "walrus",
-		"size":   10,
-	}).Info("A group of walrus emerges from the ocean")
-
-	log.WithFields(logrus.Fields{
-		"omg":    true,
-		"number": 122,
-	}).Warn("The group's number increased tremendously!")
-
-	log.WithFields(logrus.Fields{
-		"animal": "orca",
-		"size":   9009,
-	}).Panic("It's over 9000!")
-}

examples/hook/hook.go

@@ -1,35 +0,0 @@
-package main
-
-import (
-	"github.com/Sirupsen/logrus"
-	"github.com/Sirupsen/logrus/hooks/airbrake"
-	"github.com/tobi/airbrake-go"
-)
-
-var log = logrus.New()
-
-func init() {
-	log.Formatter = new(logrus.TextFormatter) // default
-	log.Hooks.Add(new(logrus_airbrake.AirbrakeHook))
-}
-
-func main() {
-	airbrake.Endpoint = "https://exceptions.whatever.com/notifier_api/v2/notices.xml"
-	airbrake.ApiKey = "whatever"
-	airbrake.Environment = "production"
-
-	log.WithFields(logrus.Fields{
-		"animal": "walrus",
-		"size":   10,
-	}).Info("A group of walrus emerges from the ocean")
-
-	log.WithFields(logrus.Fields{
-		"omg":    true,
-		"number": 122,
-	}).Warn("The group's number increased tremendously!")
-
-	log.WithFields(logrus.Fields{
-		"omg":    true,
-		"number": 100,
-	}).Fatal("The ice breaks!")
-}

exported.go

@@ -1,7 +1,9 @@
 package logrus
 
 import (
+	"context"
 	"io"
+	"time"
 )
 
 var (
@@ -9,37 +11,54 @@ var (
 	std = New()
 )
 
+func StandardLogger() *Logger {
+	return std
+}
+
 // SetOutput sets the standard logger output.
 func SetOutput(out io.Writer) {
-	std.mu.Lock()
+	std.SetOutput(out)
-	defer std.mu.Unlock()
-	std.Out = out
 }
 
 // SetFormatter sets the standard logger formatter.
 func SetFormatter(formatter Formatter) {
-	std.mu.Lock()
+	std.SetFormatter(formatter)
-	defer std.mu.Unlock()
+}
-	std.Formatter = formatter
+
+// SetReportCaller sets whether the standard logger will include the calling
+// method as a field.
+func SetReportCaller(include bool) {
+	std.SetReportCaller(include)
 }
 
 // SetLevel sets the standard logger level.
 func SetLevel(level Level) {
-	std.mu.Lock()
+	std.SetLevel(level)
-	defer std.mu.Unlock()
-	std.Level = level
 }
 
 // GetLevel returns the standard logger level.
 func GetLevel() Level {
-	return std.Level
+	return std.GetLevel()
+}
+
+// IsLevelEnabled checks if the log level of the standard logger is greater than the level param
+func IsLevelEnabled(level Level) bool {
+	return std.IsLevelEnabled(level)
 }
 
 // AddHook adds a hook to the standard logger hooks.
 func AddHook(hook Hook) {
-	std.mu.Lock()
+	std.AddHook(hook)
-	defer std.mu.Unlock()
+}
-	std.Hooks.Add(hook)
+
+// WithError creates an entry from the standard logger and adds an error to it, using the value defined in ErrorKey as key.
+func WithError(err error) *Entry {
+	return std.WithField(ErrorKey, err)
+}
+
+// WithContext creates an entry from the standard logger and adds a context to it.
+func WithContext(ctx context.Context) *Entry {
+	return std.WithContext(ctx)
 }
 
 // WithField creates an entry from the standard logger and adds a field to
@@ -61,6 +80,20 @@ func WithFields(fields Fields) *Entry {
 	return std.WithFields(fields)
 }
 
+// WithTime creates an entry from the standard logger and overrides the time of
+// logs generated with it.
+//
+// Note that it doesn't log until you call Debug, Print, Info, Warn, Fatal
+// or Panic on the Entry it returns.
+func WithTime(t time.Time) *Entry {
+	return std.WithTime(t)
+}
+
+// Trace logs a message at level Trace on the standard logger.
+func Trace(args ...interface{}) {
+	std.Trace(args...)
+}
+
 // Debug logs a message at level Debug on the standard logger.
 func Debug(args ...interface{}) {
 	std.Debug(args...)
@@ -96,11 +129,61 @@ func Panic(args ...interface{}) {
 	std.Panic(args...)
 }
 
-// Fatal logs a message at level Fatal on the standard logger.
+// Fatal logs a message at level Fatal on the standard logger then the process will exit with status set to 1.
 func Fatal(args ...interface{}) {
 	std.Fatal(args...)
 }
 
+// TraceFn logs a message from a func at level Trace on the standard logger.
+func TraceFn(fn LogFunction) {
+	std.TraceFn(fn)
+}
+
+// DebugFn logs a message from a func at level Debug on the standard logger.
+func DebugFn(fn LogFunction) {
+	std.DebugFn(fn)
+}
+
+// PrintFn logs a message from a func at level Info on the standard logger.
+func PrintFn(fn LogFunction) {
+	std.PrintFn(fn)
+}
+
+// InfoFn logs a message from a func at level Info on the standard logger.
+func InfoFn(fn LogFunction) {
+	std.InfoFn(fn)
+}
+
+// WarnFn logs a message from a func at level Warn on the standard logger.
+func WarnFn(fn LogFunction) {
+	std.WarnFn(fn)
+}
+
+// WarningFn logs a message from a func at level Warn on the standard logger.
+func WarningFn(fn LogFunction) {
+	std.WarningFn(fn)
+}
+
+// ErrorFn logs a message from a func at level Error on the standard logger.
+func ErrorFn(fn LogFunction) {
+	std.ErrorFn(fn)
+}
+
+// PanicFn logs a message from a func at level Panic on the standard logger.
+func PanicFn(fn LogFunction) {
+	std.PanicFn(fn)
+}
+
+// FatalFn logs a message from a func at level Fatal on the standard logger then the process will exit with status set to 1.
+func FatalFn(fn LogFunction) {
+	std.FatalFn(fn)
+}
+
+// Tracef logs a message at level Trace on the standard logger.
+func Tracef(format string, args ...interface{}) {
+	std.Tracef(format, args...)
+}
+
 // Debugf logs a message at level Debug on the standard logger.
 func Debugf(format string, args ...interface{}) {
 	std.Debugf(format, args...)
@@ -136,11 +219,16 @@ func Panicf(format string, args ...interface{}) {
 	std.Panicf(format, args...)
 }
 
-// Fatalf logs a message at level Fatal on the standard logger.
+// Fatalf logs a message at level Fatal on the standard logger then the process will exit with status set to 1.
 func Fatalf(format string, args ...interface{}) {
 	std.Fatalf(format, args...)
 }
 
+// Traceln logs a message at level Trace on the standard logger.
+func Traceln(args ...interface{}) {
+	std.Traceln(args...)
+}
+
 // Debugln logs a message at level Debug on the standard logger.
 func Debugln(args ...interface{}) {
 	std.Debugln(args...)
@@ -176,7 +264,7 @@ func Panicln(args ...interface{}) {
 	std.Panicln(args...)
 }
 
-// Fatalln logs a message at level Fatal on the standard logger.
+// Fatalln logs a message at level Fatal on the standard logger then the process will exit with status set to 1.
 func Fatalln(args ...interface{}) {
 	std.Fatalln(args...)
 }

formatter.go

@@ -1,5 +1,18 @@
 package logrus
 
+import "time"
+
+// Default key names for the default fields
+const (
+	defaultTimestampFormat = time.RFC3339
+	FieldKeyMsg            = "msg"
+	FieldKeyLevel          = "level"
+	FieldKeyTime           = "time"
+	FieldKeyLogrusError    = "logrus_error"
+	FieldKeyFunc           = "func"
+	FieldKeyFile           = "file"
+)
+
 // The Formatter interface is used to implement a custom Formatter. It takes an
 // `Entry`. It exposes all the fields, including the default ones:
 //
@@ -14,7 +27,7 @@ type Formatter interface {
 	Format(*Entry) ([]byte, error)
 }
 
-// This is to not silently overwrite `time`, `msg` and `level` fields when
+// This is to not silently overwrite `time`, `msg`, `func` and `level` fields when
 // dumping it. If this code wasn't there doing:
 //
 //  logrus.WithField("level", 1).Info("hello")
@@ -26,19 +39,40 @@ type Formatter interface {
 //
 // It's not exported because it's still using Data in an opinionated way. It's to
 // avoid code duplication between the two default formatters.
-func prefixFieldClashes(data Fields) {
+func prefixFieldClashes(data Fields, fieldMap FieldMap, reportCaller bool) {
-	_, ok := data["time"]
+	timeKey := fieldMap.resolve(FieldKeyTime)
-	if ok {
+	if t, ok := data[timeKey]; ok {
-		data["fields.time"] = data["time"]
+		data["fields."+timeKey] = t
+		delete(data, timeKey)
 	}
 
-	_, ok = data["msg"]
+	msgKey := fieldMap.resolve(FieldKeyMsg)
-	if ok {
+	if m, ok := data[msgKey]; ok {
-		data["fields.msg"] = data["msg"]
+		data["fields."+msgKey] = m
+		delete(data, msgKey)
 	}
 
-	_, ok = data["level"]
+	levelKey := fieldMap.resolve(FieldKeyLevel)
-	if ok {
+	if l, ok := data[levelKey]; ok {
-		data["fields.level"] = data["level"]
+		data["fields."+levelKey] = l
+		delete(data, levelKey)
+	}
+
+	logrusErrKey := fieldMap.resolve(FieldKeyLogrusError)
+	if l, ok := data[logrusErrKey]; ok {
+		data["fields."+logrusErrKey] = l
+		delete(data, logrusErrKey)
+	}
+
+	// If reportCaller is not set, 'func' will not conflict.
+	if reportCaller {
+		funcKey := fieldMap.resolve(FieldKeyFunc)
+		if l, ok := data[funcKey]; ok {
+			data["fields."+funcKey] = l
+		}
+		fileKey := fieldMap.resolve(FieldKeyFile)
+		if l, ok := data[fileKey]; ok {
+			data["fields."+fileKey] = l
+		}
 	}
 }

formatter_bench_test.go

@@ -1,6 +1,7 @@
 package logrus
 
 import (
+	"fmt"
 	"testing"
 	"time"
 )
@@ -45,6 +46,15 @@ var largeFields = Fields{
 	"entries":   "yeah",
 }
 
+var errorFields = Fields{
+	"foo": fmt.Errorf("bar"),
+	"baz": fmt.Errorf("qux"),
+}
+
+func BenchmarkErrorTextFormatter(b *testing.B) {
+	doBenchmark(b, &TextFormatter{DisableColors: true}, errorFields)
+}
+
 func BenchmarkSmallTextFormatter(b *testing.B) {
 	doBenchmark(b, &TextFormatter{DisableColors: true}, smallFields)
 }
@@ -70,11 +80,14 @@ func BenchmarkLargeJSONFormatter(b *testing.B) {
 }
 
 func doBenchmark(b *testing.B, formatter Formatter, fields Fields) {
+	logger := New()
+
 	entry := &Entry{
 		Time:    time.Time{},
 		Level:   InfoLevel,
 		Message: "message",
 		Data:    fields,
+		Logger:  logger,
 	}
 	var d []byte
 	var err error

go.mod

@@ -0,0 +1,9 @@
+module git.internal/re/logrus
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/stretchr/testify v1.7.0
+	golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8
+)
+
+go 1.13

go.sum

@@ -0,0 +1,14 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 h1:0A+M6Uqn+Eje4kHMK80dtF3JCXC4ykBgQG4Fe06QRhQ=
+golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

hook_test.go

@@ -1,9 +1,18 @@
-package logrus
+package logrus_test
 
 import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"sync"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	. "git.internal/re/logrus"
+	"git.internal/re/logrus/hooks/test"
+	. "git.internal/re/logrus/internal/testutils"
 )
 
 type TestHook struct {
@@ -17,6 +26,7 @@ func (hook *TestHook) Fire(entry *Entry) error {
 
 func (hook *TestHook) Levels() []Level {
 	return []Level{
+		TraceLevel,
 		DebugLevel,
 		InfoLevel,
 		WarnLevel,
@@ -39,8 +49,7 @@ func TestHookFires(t *testing.T) {
 	})
 }
 
-type ModifyHook struct {
+type ModifyHook struct{}
-}
 
 func (hook *ModifyHook) Fire(entry *Entry) error {
 	entry.Data["wow"] = "whale"
@@ -49,6 +58,7 @@ func (hook *ModifyHook) Fire(entry *Entry) error {
 
 func (hook *ModifyHook) Levels() []Level {
 	return []Level{
+		TraceLevel,
 		DebugLevel,
 		InfoLevel,
 		WarnLevel,
@@ -84,6 +94,46 @@ func TestCanFireMultipleHooks(t *testing.T) {
 	})
 }
 
+type SingleLevelModifyHook struct {
+	ModifyHook
+}
+
+func (h *SingleLevelModifyHook) Levels() []Level {
+	return []Level{InfoLevel}
+}
+
+func TestHookEntryIsPristine(t *testing.T) {
+	l := New()
+	b := &bytes.Buffer{}
+	l.Formatter = &JSONFormatter{}
+	l.Out = b
+	l.AddHook(&SingleLevelModifyHook{})
+
+	l.Error("error message")
+	data := map[string]string{}
+	err := json.Unmarshal(b.Bytes(), &data)
+	require.NoError(t, err)
+	_, ok := data["wow"]
+	require.False(t, ok)
+	b.Reset()
+
+	l.Info("error message")
+	data = map[string]string{}
+	err = json.Unmarshal(b.Bytes(), &data)
+	require.NoError(t, err)
+	_, ok = data["wow"]
+	require.True(t, ok)
+	b.Reset()
+
+	l.Error("error message")
+	data = map[string]string{}
+	err = json.Unmarshal(b.Bytes(), &data)
+	require.NoError(t, err)
+	_, ok = data["wow"]
+	require.False(t, ok)
+	b.Reset()
+}
+
 type ErrorHook struct {
 	Fired bool
 }
@@ -120,3 +170,64 @@ func TestErrorHookShouldFireOnError(t *testing.T) {
 		assert.Equal(t, hook.Fired, true)
 	})
 }
+
+func TestAddHookRace(t *testing.T) {
+	var wg sync.WaitGroup
+	wg.Add(2)
+	hook := new(ErrorHook)
+	LogAndAssertJSON(t, func(log *Logger) {
+		go func() {
+			defer wg.Done()
+			log.AddHook(hook)
+		}()
+		go func() {
+			defer wg.Done()
+			log.Error("test")
+		}()
+		wg.Wait()
+	}, func(fields Fields) {
+		// the line may have been logged
+		// before the hook was added, so we can't
+		// actually assert on the hook
+	})
+}
+
+func TestAddHookRace2(t *testing.T) {
+	t.Parallel()
+
+	for i := 0; i < 3; i++ {
+		testname := fmt.Sprintf("Test %d", i)
+		t.Run(testname, func(t *testing.T) {
+			t.Parallel()
+
+			_ = test.NewGlobal()
+			Info(testname)
+		})
+	}
+}
+
+type HookCallFunc struct {
+	F func()
+}
+
+func (h *HookCallFunc) Levels() []Level {
+	return AllLevels
+}
+
+func (h *HookCallFunc) Fire(e *Entry) error {
+	h.F()
+	return nil
+}
+
+func TestHookFireOrder(t *testing.T) {
+	checkers := []string{}
+	h := LevelHooks{}
+	h.Add(&HookCallFunc{F: func() { checkers = append(checkers, "first hook") }})
+	h.Add(&HookCallFunc{F: func() { checkers = append(checkers, "second hook") }})
+	h.Add(&HookCallFunc{F: func() { checkers = append(checkers, "third hook") }})
+
+	if err := h.Fire(InfoLevel, &Entry{}); err != nil {
+		t.Error("unexpected error:", err)
+	}
+	require.Equal(t, []string{"first hook", "second hook", "third hook"}, checkers)
+}

hooks.go

@@ -11,11 +11,11 @@ type Hook interface {
 }
 
 // Internal type for storing the hooks on a logger instance.
-type levelHooks map[Level][]Hook
+type LevelHooks map[Level][]Hook
 
 // Add a hook to an instance of logger. This is called with
 // `log.Hooks.Add(new(MyHook))` where `MyHook` implements the `Hook` interface.
-func (hooks levelHooks) Add(hook Hook) {
+func (hooks LevelHooks) Add(hook Hook) {
 	for _, level := range hook.Levels() {
 		hooks[level] = append(hooks[level], hook)
 	}
@@ -23,7 +23,7 @@ func (hooks levelHooks) Add(hook Hook) {
 
 // Fire all the hooks for the passed level. Used by `entry.log` to fire
 // appropriate hooks for a log entry.
-func (hooks levelHooks) Fire(level Level, entry *Entry) error {
+func (hooks LevelHooks) Fire(level Level, entry *Entry) error {
 	for _, hook := range hooks[level] {
 		if err := hook.Fire(entry); err != nil {
 			return err

hooks/airbrake/airbrake.go

@@ -1,54 +0,0 @@
-package logrus_airbrake
-
-import (
-	"github.com/Sirupsen/logrus"
-	"github.com/tobi/airbrake-go"
-)
-
-// AirbrakeHook to send exceptions to an exception-tracking service compatible
-// with the Airbrake API. You must set:
-// * airbrake.Endpoint
-// * airbrake.ApiKey
-// * airbrake.Environment (only sends exceptions when set to "production")
-//
-// Before using this hook, to send an error. Entries that trigger an Error,
-// Fatal or Panic should now include an "error" field to send to Airbrake.
-type AirbrakeHook struct{}
-
-func (hook *AirbrakeHook) Fire(entry *logrus.Entry) error {
-	if entry.Data["error"] == nil {
-		entry.Logger.WithFields(logrus.Fields{
-			"source":   "airbrake",
-			"endpoint": airbrake.Endpoint,
-		}).Warn("Exceptions sent to Airbrake must have an 'error' key with the error")
-		return nil
-	}
-
-	err, ok := entry.Data["error"].(error)
-	if !ok {
-		entry.Logger.WithFields(logrus.Fields{
-			"source":   "airbrake",
-			"endpoint": airbrake.Endpoint,
-		}).Warn("Exceptions sent to Airbrake must have an `error` key of type `error`")
-		return nil
-	}
-
-	airErr := airbrake.Notify(err)
-	if airErr != nil {
-		entry.Logger.WithFields(logrus.Fields{
-			"source":   "airbrake",
-			"endpoint": airbrake.Endpoint,
-			"error":    airErr,
-		}).Warn("Failed to send error to Airbrake")
-	}
-
-	return nil
-}
-
-func (hook *AirbrakeHook) Levels() []logrus.Level {
-	return []logrus.Level{
-		logrus.ErrorLevel,
-		logrus.FatalLevel,
-		logrus.PanicLevel,
-	}
-}

hooks/papertrail/README.md

@@ -1,28 +0,0 @@
-# Papertrail Hook for Logrus <img src="http://i.imgur.com/hTeVwmJ.png" width="40" height="40" alt=":walrus:" class="emoji" title=":walrus:" />
-
-[Papertrail](https://papertrailapp.com) provides hosted log management. Once stored in Papertrail, you can [group](http://help.papertrailapp.com/kb/how-it-works/groups/) your logs on various dimensions, [search](http://help.papertrailapp.com/kb/how-it-works/search-syntax) them, and trigger [alerts](http://help.papertrailapp.com/kb/how-it-works/alerts).
-
-In most deployments, you'll want to send logs to Papertrail via their [remote_syslog](http://help.papertrailapp.com/kb/configuration/configuring-centralized-logging-from-text-log-files-in-unix/) daemon, which requires no application-specific configuration. This hook is intended for relatively low-volume logging, likely in managed cloud hosting deployments where installing `remote_syslog` is not possible.
-
-## Usage
-
-You can find your Papertrail UDP port on your [Papertrail account page](https://papertrailapp.com/account/destinations). Substitute it below for `YOUR_PAPERTRAIL_UDP_PORT`.
-
-For `YOUR_APP_NAME`, substitute a short string that will readily identify your application or service in the logs.
-
-```go
-import (
-  "log/syslog"
-  "github.com/Sirupsen/logrus"
-  "github.com/Sirupsen/logrus/hooks/papertrail"
-)
-
-func main() {
-  log       := logrus.New()
-  hook, err := logrus_papertrail.NewPapertrailHook("logs.papertrailapp.com", YOUR_PAPERTRAIL_UDP_PORT, YOUR_APP_NAME)
-
-  if err == nil {
-    log.Hooks.Add(hook)
-  }
-}
-```

hooks/papertrail/papertrail.go

@@ -1,54 +0,0 @@
-package logrus_papertrail
-
-import (
-	"fmt"
-	"net"
-	"os"
-	"time"
-
-	"github.com/Sirupsen/logrus"
-)
-
-const (
-	format = "Jan 2 15:04:05"
-)
-
-// PapertrailHook to send logs to a logging service compatible with the Papertrail API.
-type PapertrailHook struct {
-	Host    string
-	Port    int
-	AppName string
-	UDPConn net.Conn
-}
-
-// NewPapertrailHook creates a hook to be added to an instance of logger.
-func NewPapertrailHook(host string, port int, appName string) (*PapertrailHook, error) {
-	conn, err := net.Dial("udp", fmt.Sprintf("%s:%d", host, port))
-	return &PapertrailHook{host, port, appName, conn}, err
-}
-
-// Fire is called when a log event is fired.
-func (hook *PapertrailHook) Fire(entry *logrus.Entry) error {
-	date := time.Now().Format(format)
-	payload := fmt.Sprintf("<22> %s %s: [%s] %s", date, hook.AppName, entry.Level, entry.Message)
-
-	bytesWritten, err := hook.UDPConn.Write([]byte(payload))
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "Unable to send log line to Papertrail via UDP. Wrote %d bytes before error: %v", bytesWritten, err)
-		return err
-	}
-
-	return nil
-}
-
-// Levels returns the available logging levels.
-func (hook *PapertrailHook) Levels() []logrus.Level {
-	return []logrus.Level{
-		logrus.PanicLevel,
-		logrus.FatalLevel,
-		logrus.ErrorLevel,
-		logrus.WarnLevel,
-		logrus.InfoLevel,
-		logrus.DebugLevel,
-	}
-}

hooks/papertrail/papertrail_test.go

@@ -1,26 +0,0 @@
-package logrus_papertrail
-
-import (
-	"fmt"
-	"testing"
-
-	"github.com/Sirupsen/logrus"
-	"github.com/stvp/go-udp-testing"
-)
-
-func TestWritingToUDP(t *testing.T) {
-	port := 16661
-	udp.SetAddr(fmt.Sprintf(":%d", port))
-
-	hook, err := NewPapertrailHook("localhost", port, "test")
-	if err != nil {
-		t.Errorf("Unable to connect to local UDP server.")
-	}
-
-	log := logrus.New()
-	log.Hooks.Add(hook)
-
-	udp.ShouldReceive(t, "foo", func() {
-		log.Info("foo")
-	})
-}

hooks/sentry/README.md

@@ -1,61 +0,0 @@
-# Sentry Hook for Logrus <img src="http://i.imgur.com/hTeVwmJ.png" width="40" height="40" alt=":walrus:" class="emoji" title=":walrus:" />
-
-[Sentry](https://getsentry.com) provides both self-hosted and hosted
-solutions for exception tracking.
-Both client and server are
-[open source](https://github.com/getsentry/sentry).
-
-## Usage
-
-Every sentry application defined on the server gets a different
-[DSN](https://www.getsentry.com/docs/). In the example below replace
-`YOUR_DSN` with the one created for your application.
-
-```go
-import (
-  "github.com/Sirupsen/logrus"
-  "github.com/Sirupsen/logrus/hooks/sentry"
-)
-
-func main() {
-  log       := logrus.New()
-  hook, err := logrus_sentry.NewSentryHook(YOUR_DSN, []logrus.Level{
-    logrus.PanicLevel,
-    logrus.FatalLevel,
-    logrus.ErrorLevel,
-  })
-
-  if err == nil {
-    log.Hooks.Add(hook)
-  }
-}
-```
-
-## Special fields
-
-Some logrus fields have a special meaning in this hook,
-these are server_name and logger.
-When logs are sent to sentry these fields are treated differently.
-- server_name (also known as hostname) is the name of the server which
-is logging the event (hostname.example.com)
-- logger is the part of the application which is logging the event.
-In go this usually means setting it to the name of the package.
-
-## Timeout
-
-`Timeout` is the time the sentry hook will wait for a response
-from the sentry server.
-
-If this time elapses with no response from
-the server an error will be returned.
-
-If `Timeout` is set to 0 the SentryHook will not wait for a reply
-and will assume a correct delivery.
-
-The SentryHook has a default timeout of `100 milliseconds` when created
-with a call to `NewSentryHook`. This can be changed by assigning a value to the `Timeout` field:
-
-```go
-hook, _ := logrus_sentry.NewSentryHook(...)
-hook.Timeout = 20*time.Seconds
-```

hooks/sentry/sentry.go

@@ -1,100 +0,0 @@
-package logrus_sentry
-
-import (
-	"fmt"
-	"time"
-
-	"github.com/Sirupsen/logrus"
-	"github.com/getsentry/raven-go"
-)
-
-var (
-	severityMap = map[logrus.Level]raven.Severity{
-		logrus.DebugLevel: raven.DEBUG,
-		logrus.InfoLevel:  raven.INFO,
-		logrus.WarnLevel:  raven.WARNING,
-		logrus.ErrorLevel: raven.ERROR,
-		logrus.FatalLevel: raven.FATAL,
-		logrus.PanicLevel: raven.FATAL,
-	}
-)
-
-func getAndDel(d logrus.Fields, key string) (string, bool) {
-	var (
-		ok  bool
-		v   interface{}
-		val string
-	)
-	if v, ok = d[key]; !ok {
-		return "", false
-	}
-
-	if val, ok = v.(string); !ok {
-		return "", false
-	}
-	delete(d, key)
-	return val, true
-}
-
-// SentryHook delivers logs to a sentry server.
-type SentryHook struct {
-	// Timeout sets the time to wait for a delivery error from the sentry server.
-	// If this is set to zero the server will not wait for any response and will
-	// consider the message correctly sent
-	Timeout time.Duration
-
-	client *raven.Client
-	levels []logrus.Level
-}
-
-// NewSentryHook creates a hook to be added to an instance of logger
-// and initializes the raven client.
-// This method sets the timeout to 100 milliseconds.
-func NewSentryHook(DSN string, levels []logrus.Level) (*SentryHook, error) {
-	client, err := raven.NewClient(DSN, nil)
-	if err != nil {
-		return nil, err
-	}
-	return &SentryHook{100 * time.Millisecond, client, levels}, nil
-}
-
-// Called when an event should be sent to sentry
-// Special fields that sentry uses to give more information to the server
-// are extracted from entry.Data (if they are found)
-// These fields are: logger and server_name
-func (hook *SentryHook) Fire(entry *logrus.Entry) error {
-	packet := &raven.Packet{
-		Message:   entry.Message,
-		Timestamp: raven.Timestamp(entry.Time),
-		Level:     severityMap[entry.Level],
-		Platform:  "go",
-	}
-
-	d := entry.Data
-
-	if logger, ok := getAndDel(d, "logger"); ok {
-		packet.Logger = logger
-	}
-	if serverName, ok := getAndDel(d, "server_name"); ok {
-		packet.ServerName = serverName
-	}
-	packet.Extra = map[string]interface{}(d)
-
-	_, errCh := hook.client.Capture(packet, nil)
-	timeout := hook.Timeout
-	if timeout != 0 {
-		timeoutCh := time.After(timeout)
-		select {
-		case err := <-errCh:
-			return err
-		case <-timeoutCh:
-			return fmt.Errorf("no response from sentry server in %s", timeout)
-		}
-	}
-	return nil
-}
-
-// Levels returns the available logging levels.
-func (hook *SentryHook) Levels() []logrus.Level {
-	return hook.levels
-}

hooks/sentry/sentry_test.go

@@ -1,97 +0,0 @@
-package logrus_sentry
-
-import (
-	"encoding/json"
-	"fmt"
-	"io/ioutil"
-	"net/http"
-	"net/http/httptest"
-	"strings"
-	"testing"
-
-	"github.com/Sirupsen/logrus"
-	"github.com/getsentry/raven-go"
-)
-
-const (
-	message     = "error message"
-	server_name = "testserver.internal"
-	logger_name = "test.logger"
-)
-
-func getTestLogger() *logrus.Logger {
-	l := logrus.New()
-	l.Out = ioutil.Discard
-	return l
-}
-
-func WithTestDSN(t *testing.T, tf func(string, <-chan *raven.Packet)) {
-	pch := make(chan *raven.Packet, 1)
-	s := httptest.NewServer(http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
-		defer req.Body.Close()
-		d := json.NewDecoder(req.Body)
-		p := &raven.Packet{}
-		err := d.Decode(p)
-		if err != nil {
-			t.Fatal(err.Error())
-		}
-
-		pch <- p
-	}))
-	defer s.Close()
-
-	fragments := strings.SplitN(s.URL, "://", 2)
-	dsn := fmt.Sprintf(
-		"%s://public:secret@%s/sentry/project-id",
-		fragments[0],
-		fragments[1],
-	)
-	tf(dsn, pch)
-}
-
-func TestSpecialFields(t *testing.T) {
-	WithTestDSN(t, func(dsn string, pch <-chan *raven.Packet) {
-		logger := getTestLogger()
-
-		hook, err := NewSentryHook(dsn, []logrus.Level{
-			logrus.ErrorLevel,
-		})
-
-		if err != nil {
-			t.Fatal(err.Error())
-		}
-		logger.Hooks.Add(hook)
-		logger.WithFields(logrus.Fields{
-			"server_name": server_name,
-			"logger":      logger_name,
-		}).Error(message)
-
-		packet := <-pch
-		if packet.Logger != logger_name {
-			t.Errorf("logger should have been %s, was %s", logger_name, packet.Logger)
-		}
-
-		if packet.ServerName != server_name {
-			t.Errorf("server_name should have been %s, was %s", server_name, packet.ServerName)
-		}
-	})
-}
-
-func TestSentryHandler(t *testing.T) {
-	WithTestDSN(t, func(dsn string, pch <-chan *raven.Packet) {
-		logger := getTestLogger()
-		hook, err := NewSentryHook(dsn, []logrus.Level{
-			logrus.ErrorLevel,
-		})
-		if err != nil {
-			t.Fatal(err.Error())
-		}
-		logger.Hooks.Add(hook)
-
-		logger.Error(message)
-		packet := <-pch
-		if packet.Message != message {
-			t.Errorf("message should have been %s, was %s", message, packet.Message)
-		}
-	})
-}

hooks/syslog/README.md

@@ -5,13 +5,32 @@
 ```go
 import (
   "log/syslog"
-  "github.com/Sirupsen/logrus"
+  "git.internal/re/logrus"
-  logrus_syslog "github.com/Sirupsen/logrus/hooks/syslog"
+  lSyslog "git.internal/re/logrus/hooks/syslog"
 )
 
 func main() {
   log       := logrus.New()
-  hook, err := logrus_syslog.NewSyslogHook("udp", "localhost:514", syslog.LOG_INFO, "")
+  hook, err := lSyslog.NewSyslogHook("udp", "localhost:514", syslog.LOG_INFO, "")
+
+  if err == nil {
+    log.Hooks.Add(hook)
+  }
+}
+```
+
+If you want to connect to local syslog (Ex. "/dev/log" or "/var/run/syslog" or "/var/run/log"). Just assign empty string to the first two parameters of `NewSyslogHook`. It should look like the following.
+
+```go
+import (
+  "log/syslog"
+  "git.internal/re/logrus"
+  lSyslog "git.internal/re/logrus/hooks/syslog"
+)
+
+func main() {
+  log       := logrus.New()
+  hook, err := lSyslog.NewSyslogHook("", "", syslog.LOG_INFO, "")
 
   if err == nil {
     log.Hooks.Add(hook)

hooks/syslog/syslog.go

@@ -1,10 +1,14 @@
-package logrus_syslog
+//go:build !windows && !nacl && !plan9
+// +build !windows,!nacl,!plan9
+
+package syslog
 
 import (
 	"fmt"
-	"github.com/Sirupsen/logrus"
 	"log/syslog"
 	"os"
+
+	"git.internal/re/logrus"
 )
 
 // SyslogHook to send logs via syslog.
@@ -40,7 +44,7 @@ func (hook *SyslogHook) Fire(entry *logrus.Entry) error {
 		return hook.Writer.Warning(line)
 	case logrus.InfoLevel:
 		return hook.Writer.Info(line)
-	case logrus.DebugLevel:
+	case logrus.DebugLevel, logrus.TraceLevel:
 		return hook.Writer.Debug(line)
 	default:
 		return nil
@@ -48,12 +52,5 @@ func (hook *SyslogHook) Fire(entry *logrus.Entry) error {
 }
 
 func (hook *SyslogHook) Levels() []logrus.Level {
-	return []logrus.Level{
+	return logrus.AllLevels
-		logrus.PanicLevel,
-		logrus.FatalLevel,
-		logrus.ErrorLevel,
-		logrus.WarnLevel,
-		logrus.InfoLevel,
-		logrus.DebugLevel,
-	}
 }

hooks/syslog/syslog_test.go

@@ -1,15 +1,18 @@
-package logrus_syslog
+//go:build !windows && !nacl && !plan9
+// +build !windows,!nacl,!plan9
+
+package syslog
 
 import (
-	"github.com/Sirupsen/logrus"
 	"log/syslog"
 	"testing"
+
+	"git.internal/re/logrus"
 )
 
 func TestLocalhostAddAndPrint(t *testing.T) {
 	log := logrus.New()
 	hook, err := NewSyslogHook("udp", "localhost:514", syslog.LOG_INFO, "")
-
 	if err != nil {
 		t.Errorf("Unable to connect to local syslog.")
 	}

hooks/test/test.go

@@ -0,0 +1,85 @@
+// The Test package is used for testing logrus.
+// It provides a simple hooks which register logged messages.
+package test
+
+import (
+	"io/ioutil"
+	"sync"
+
+	"git.internal/re/logrus"
+)
+
+// Hook is a hook designed for dealing with logs in test scenarios.
+type Hook struct {
+	// Entries is an array of all entries that have been received by this hook.
+	// For safe access, use the AllEntries() method, rather than reading this
+	// value directly.
+	Entries []logrus.Entry
+	mu      sync.RWMutex
+}
+
+// NewGlobal installs a test hook for the global logger.
+func NewGlobal() *Hook {
+	hook := new(Hook)
+	logrus.AddHook(hook)
+
+	return hook
+}
+
+// NewLocal installs a test hook for a given local logger.
+func NewLocal(logger *logrus.Logger) *Hook {
+	hook := new(Hook)
+	logger.Hooks.Add(hook)
+
+	return hook
+}
+
+// NewNullLogger creates a discarding logger and installs the test hook.
+func NewNullLogger() (*logrus.Logger, *Hook) {
+	logger := logrus.New()
+	logger.Out = ioutil.Discard
+
+	return logger, NewLocal(logger)
+}
+
+func (t *Hook) Fire(e *logrus.Entry) error {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.Entries = append(t.Entries, *e)
+	return nil
+}
+
+func (t *Hook) Levels() []logrus.Level {
+	return logrus.AllLevels
+}
+
+// LastEntry returns the last entry that was logged or nil.
+func (t *Hook) LastEntry() *logrus.Entry {
+	t.mu.RLock()
+	defer t.mu.RUnlock()
+	i := len(t.Entries) - 1
+	if i < 0 {
+		return nil
+	}
+	return &t.Entries[i]
+}
+
+// AllEntries returns all entries that were logged.
+func (t *Hook) AllEntries() []*logrus.Entry {
+	t.mu.RLock()
+	defer t.mu.RUnlock()
+	// Make a copy so the returned value won't race with future log requests
+	entries := make([]*logrus.Entry, len(t.Entries))
+	for i := 0; i < len(t.Entries); i++ {
+		// Make a copy, for safety
+		entries[i] = &t.Entries[i]
+	}
+	return entries
+}
+
+// Reset removes all Entries from this test hook.
+func (t *Hook) Reset() {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.Entries = make([]logrus.Entry, 0)
+}

hooks/test/test_test.go

@@ -0,0 +1,84 @@
+package test
+
+import (
+	"math/rand"
+	"sync"
+	"testing"
+	"time"
+
+	"git.internal/re/logrus"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAllHooks(t *testing.T) {
+	assert := assert.New(t)
+
+	logger, hook := NewNullLogger()
+	assert.Nil(hook.LastEntry())
+	assert.Equal(0, len(hook.Entries))
+
+	logger.Error("Hello error")
+	assert.Equal(logrus.ErrorLevel, hook.LastEntry().Level)
+	assert.Equal("Hello error", hook.LastEntry().Message)
+	assert.Equal(1, len(hook.Entries))
+
+	logger.Warn("Hello warning")
+	assert.Equal(logrus.WarnLevel, hook.LastEntry().Level)
+	assert.Equal("Hello warning", hook.LastEntry().Message)
+	assert.Equal(2, len(hook.Entries))
+
+	hook.Reset()
+	assert.Nil(hook.LastEntry())
+	assert.Equal(0, len(hook.Entries))
+
+	hook = NewGlobal()
+
+	logrus.Error("Hello error")
+	assert.Equal(logrus.ErrorLevel, hook.LastEntry().Level)
+	assert.Equal("Hello error", hook.LastEntry().Message)
+	assert.Equal(1, len(hook.Entries))
+}
+
+func TestLoggingWithHooksRace(t *testing.T) {
+	rand.Seed(time.Now().Unix())
+	unlocker := rand.Int() % 100
+
+	assert := assert.New(t)
+	logger, hook := NewNullLogger()
+
+	var wgOne, wgAll sync.WaitGroup
+	wgOne.Add(1)
+	wgAll.Add(100)
+
+	for i := 0; i < 100; i++ {
+		go func(i int) {
+			logger.Info("info")
+			wgAll.Done()
+			if i == unlocker {
+				wgOne.Done()
+			}
+		}(i)
+	}
+
+	wgOne.Wait()
+
+	assert.Equal(logrus.InfoLevel, hook.LastEntry().Level)
+	assert.Equal("info", hook.LastEntry().Message)
+
+	wgAll.Wait()
+
+	entries := hook.AllEntries()
+	assert.Equal(100, len(entries))
+}
+
+func TestFatalWithAlternateExit(t *testing.T) {
+	assert := assert.New(t)
+
+	logger, hook := NewNullLogger()
+	logger.ExitFunc = func(code int) {}
+
+	logger.Fatal("something went very wrong")
+	assert.Equal(logrus.FatalLevel, hook.LastEntry().Level)
+	assert.Equal("something went very wrong", hook.LastEntry().Message)
+	assert.Equal(1, len(hook.Entries))
+}

hooks/writer/README.md

@@ -0,0 +1,43 @@
+# Writer Hooks for Logrus
+
+Send logs of given levels to any object with `io.Writer` interface.
+
+## Usage
+
+If you want for example send high level logs to `Stderr` and
+logs of  normal execution to `Stdout`, you could do it like this:
+
+```go
+package main
+
+import (
+	"io/ioutil"
+	"os"
+
+	log "git.internal/re/logrus"
+	"git.internal/re/logrus/hooks/writer"
+)
+
+func main() {
+	log.SetOutput(ioutil.Discard) // Send all logs to nowhere by default
+
+	log.AddHook(&writer.Hook{ // Send logs with level higher than warning to stderr
+		Writer: os.Stderr,
+		LogLevels: []log.Level{
+			log.PanicLevel,
+			log.FatalLevel,
+			log.ErrorLevel,
+			log.WarnLevel,
+		},
+	})
+	log.AddHook(&writer.Hook{ // Send info and debug logs to stdout
+		Writer: os.Stdout,
+		LogLevels: []log.Level{
+			log.InfoLevel,
+			log.DebugLevel,
+		},
+	})
+	log.Info("This will go to stdout")
+	log.Warn("This will go to stderr")
+}
+```

hooks/writer/writer.go

@@ -0,0 +1,29 @@
+package writer
+
+import (
+	"io"
+
+	log "git.internal/re/logrus"
+)
+
+// Hook is a hook that writes logs of specified LogLevels to specified Writer
+type Hook struct {
+	Writer    io.Writer
+	LogLevels []log.Level
+}
+
+// Fire will be called when some logging function is called with current hook
+// It will format log entry to string and write it to appropriate writer
+func (hook *Hook) Fire(entry *log.Entry) error {
+	line, err := entry.Bytes()
+	if err != nil {
+		return err
+	}
+	_, err = hook.Writer.Write(line)
+	return err
+}
+
+// Levels define on which log levels this hook would trigger
+func (hook *Hook) Levels() []log.Level {
+	return hook.LogLevels
+}

hooks/writer/writer_test.go

@@ -0,0 +1,38 @@
+package writer
+
+import (
+	"bytes"
+	"io/ioutil"
+	"testing"
+
+	log "git.internal/re/logrus"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestDifferentLevelsGoToDifferentWriters(t *testing.T) {
+	var a, b bytes.Buffer
+
+	log.SetFormatter(&log.TextFormatter{
+		DisableTimestamp: true,
+		DisableColors:    true,
+	})
+	log.SetOutput(ioutil.Discard) // Send all logs to nowhere by default
+
+	log.AddHook(&Hook{
+		Writer: &a,
+		LogLevels: []log.Level{
+			log.WarnLevel,
+		},
+	})
+	log.AddHook(&Hook{ // Send info and debug logs to stdout
+		Writer: &b,
+		LogLevels: []log.Level{
+			log.InfoLevel,
+		},
+	})
+	log.Warn("send to a")
+	log.Info("send to b")
+
+	assert.Equal(t, a.String(), "level=warning msg=\"send to a\"\n")
+	assert.Equal(t, b.String(), "level=info msg=\"send to b\"\n")
+}

internal/testutils/testutils.go

@@ -0,0 +1,58 @@
+package testutils
+
+import (
+	"bytes"
+	"encoding/json"
+	"strconv"
+	"strings"
+	"testing"
+
+	. "git.internal/re/logrus"
+
+	"github.com/stretchr/testify/require"
+)
+
+func LogAndAssertJSON(t *testing.T, log func(*Logger), assertions func(fields Fields)) {
+	var buffer bytes.Buffer
+	var fields Fields
+
+	logger := New()
+	logger.Out = &buffer
+	logger.Formatter = new(JSONFormatter)
+
+	log(logger)
+
+	err := json.Unmarshal(buffer.Bytes(), &fields)
+	require.Nil(t, err)
+
+	assertions(fields)
+}
+
+func LogAndAssertText(t *testing.T, log func(*Logger), assertions func(fields map[string]string)) {
+	var buffer bytes.Buffer
+
+	logger := New()
+	logger.Out = &buffer
+	logger.Formatter = &TextFormatter{
+		DisableColors: true,
+	}
+
+	log(logger)
+
+	fields := make(map[string]string)
+	for _, kv := range strings.Split(strings.TrimRight(buffer.String(), "\n"), " ") {
+		if !strings.Contains(kv, "=") {
+			continue
+		}
+		kvArr := strings.Split(kv, "=")
+		key := strings.TrimSpace(kvArr[0])
+		val := kvArr[1]
+		if kvArr[1][0] == '"' {
+			var err error
+			val, err = strconv.Unquote(val)
+			require.NoError(t, err)
+		}
+		fields[key] = val
+	}
+	assertions(fields)
+}

json_formatter.go

@@ -1,26 +1,128 @@
 package logrus
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
-	"time"
+	"runtime"
 )
 
-type JSONFormatter struct{}
+type fieldKey string
 
-func (f *JSONFormatter) Format(entry *Entry) ([]byte, error) {
+// FieldMap allows customization of the key names for default fields.
-	data := make(Fields, len(entry.Data)+3)
+type FieldMap map[fieldKey]string
-	for k, v := range entry.Data {
-		data[k] = v
-	}
-	prefixFieldClashes(data)
-	data["time"] = entry.Time.Format(time.RFC3339)
-	data["msg"] = entry.Message
-	data["level"] = entry.Level.String()
 
-	serialized, err := json.Marshal(data)
+func (f FieldMap) resolve(key fieldKey) string {
-	if err != nil {
+	if k, ok := f[key]; ok {
-		return nil, fmt.Errorf("Failed to marshal fields to JSON, %v", err)
+		return k
 	}
-	return append(serialized, '\n'), nil
+
+	return string(key)
+}
+
+// JSONFormatter formats logs into parsable json
+type JSONFormatter struct {
+	// TimestampFormat sets the format used for marshaling timestamps.
+	// The format to use is the same than for time.Format or time.Parse from the standard
+	// library.
+	// The standard Library already provides a set of predefined format.
+	TimestampFormat string
+
+	// DisableTimestamp allows disabling automatic timestamps in output
+	DisableTimestamp bool
+
+	// DisableHTMLEscape allows disabling html escaping in output
+	DisableHTMLEscape bool
+
+	// DataKey allows users to put all the log entry parameters into a nested dictionary at a given key.
+	DataKey string
+
+	// FieldMap allows users to customize the names of keys for default fields.
+	// As an example:
+	// formatter := &JSONFormatter{
+	//   	FieldMap: FieldMap{
+	// 		 FieldKeyTime:  "@timestamp",
+	// 		 FieldKeyLevel: "@level",
+	// 		 FieldKeyMsg:   "@message",
+	// 		 FieldKeyFunc:  "@caller",
+	//    },
+	// }
+	FieldMap FieldMap
+
+	// CallerPrettyfier can be set by the user to modify the content
+	// of the function and file keys in the json data when ReportCaller is
+	// activated. If any of the returned value is the empty string the
+	// corresponding key will be removed from json fields.
+	CallerPrettyfier func(*runtime.Frame) (function string, file string)
+
+	// PrettyPrint will indent all json logs
+	PrettyPrint bool
+}
+
+// Format renders a single log entry
+func (f *JSONFormatter) Format(entry *Entry) ([]byte, error) {
+	data := make(Fields, len(entry.Data)+4)
+	for k, v := range entry.Data {
+		switch v := v.(type) {
+		case error:
+			// Otherwise errors are ignored by `encoding/json`
+			// https://git.internal/re/logrus/issues/137
+			data[k] = v.Error()
+		default:
+			data[k] = v
+		}
+	}
+
+	if f.DataKey != "" {
+		newData := make(Fields, 4)
+		newData[f.DataKey] = data
+		data = newData
+	}
+
+	prefixFieldClashes(data, f.FieldMap, entry.HasCaller())
+
+	timestampFormat := f.TimestampFormat
+	if timestampFormat == "" {
+		timestampFormat = defaultTimestampFormat
+	}
+
+	if entry.err != "" {
+		data[f.FieldMap.resolve(FieldKeyLogrusError)] = entry.err
+	}
+	if !f.DisableTimestamp {
+		data[f.FieldMap.resolve(FieldKeyTime)] = entry.Time.Format(timestampFormat)
+	}
+	data[f.FieldMap.resolve(FieldKeyMsg)] = entry.Message
+	data[f.FieldMap.resolve(FieldKeyLevel)] = entry.Level.String()
+	if entry.HasCaller() {
+		funcVal := entry.Caller.Function
+		fileVal := fmt.Sprintf("%s:%d", entry.Caller.File, entry.Caller.Line)
+		if f.CallerPrettyfier != nil {
+			funcVal, fileVal = f.CallerPrettyfier(entry.Caller)
+		}
+		if funcVal != "" {
+			data[f.FieldMap.resolve(FieldKeyFunc)] = funcVal
+		}
+		if fileVal != "" {
+			data[f.FieldMap.resolve(FieldKeyFile)] = fileVal
+		}
+	}
+
+	var b *bytes.Buffer
+	if entry.Buffer != nil {
+		b = entry.Buffer
+	} else {
+		b = &bytes.Buffer{}
+	}
+
+	encoder := json.NewEncoder(b)
+	encoder.SetEscapeHTML(!f.DisableHTMLEscape)
+	if f.PrettyPrint {
+		encoder.SetIndent("", "  ")
+	}
+	if err := encoder.Encode(data); err != nil {
+		return nil, fmt.Errorf("failed to marshal fields to JSON, %w", err)
+	}
+
+	return b.Bytes(), nil
 }

json_formatter_test.go

@@ -0,0 +1,372 @@
+package logrus
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"runtime"
+	"strings"
+	"testing"
+)
+
+func TestErrorNotLost(t *testing.T) {
+	formatter := &JSONFormatter{}
+
+	b, err := formatter.Format(WithField("error", errors.New("wild walrus")))
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+
+	entry := make(map[string]interface{})
+	err = json.Unmarshal(b, &entry)
+	if err != nil {
+		t.Fatal("Unable to unmarshal formatted entry: ", err)
+	}
+
+	if entry["error"] != "wild walrus" {
+		t.Fatal("Error field not set")
+	}
+}
+
+func TestErrorNotLostOnFieldNotNamedError(t *testing.T) {
+	formatter := &JSONFormatter{}
+
+	b, err := formatter.Format(WithField("omg", errors.New("wild walrus")))
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+
+	entry := make(map[string]interface{})
+	err = json.Unmarshal(b, &entry)
+	if err != nil {
+		t.Fatal("Unable to unmarshal formatted entry: ", err)
+	}
+
+	if entry["omg"] != "wild walrus" {
+		t.Fatal("Error field not set")
+	}
+}
+
+func TestFieldClashWithTime(t *testing.T) {
+	formatter := &JSONFormatter{}
+
+	b, err := formatter.Format(WithField("time", "right now!"))
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+
+	entry := make(map[string]interface{})
+	err = json.Unmarshal(b, &entry)
+	if err != nil {
+		t.Fatal("Unable to unmarshal formatted entry: ", err)
+	}
+
+	if entry["fields.time"] != "right now!" {
+		t.Fatal("fields.time not set to original time field")
+	}
+
+	if entry["time"] != "0001-01-01T00:00:00Z" {
+		t.Fatal("time field not set to current time, was: ", entry["time"])
+	}
+}
+
+func TestFieldClashWithMsg(t *testing.T) {
+	formatter := &JSONFormatter{}
+
+	b, err := formatter.Format(WithField("msg", "something"))
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+
+	entry := make(map[string]interface{})
+	err = json.Unmarshal(b, &entry)
+	if err != nil {
+		t.Fatal("Unable to unmarshal formatted entry: ", err)
+	}
+
+	if entry["fields.msg"] != "something" {
+		t.Fatal("fields.msg not set to original msg field")
+	}
+}
+
+func TestFieldClashWithLevel(t *testing.T) {
+	formatter := &JSONFormatter{}
+
+	b, err := formatter.Format(WithField("level", "something"))
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+
+	entry := make(map[string]interface{})
+	err = json.Unmarshal(b, &entry)
+	if err != nil {
+		t.Fatal("Unable to unmarshal formatted entry: ", err)
+	}
+
+	if entry["fields.level"] != "something" {
+		t.Fatal("fields.level not set to original level field")
+	}
+}
+
+func TestFieldClashWithRemappedFields(t *testing.T) {
+	formatter := &JSONFormatter{
+		FieldMap: FieldMap{
+			FieldKeyTime:  "@timestamp",
+			FieldKeyLevel: "@level",
+			FieldKeyMsg:   "@message",
+		},
+	}
+
+	b, err := formatter.Format(WithFields(Fields{
+		"@timestamp": "@timestamp",
+		"@level":     "@level",
+		"@message":   "@message",
+		"timestamp":  "timestamp",
+		"level":      "level",
+		"msg":        "msg",
+	}))
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+
+	entry := make(map[string]interface{})
+	err = json.Unmarshal(b, &entry)
+	if err != nil {
+		t.Fatal("Unable to unmarshal formatted entry: ", err)
+	}
+
+	for _, field := range []string{"timestamp", "level", "msg"} {
+		if entry[field] != field {
+			t.Errorf("Expected field %v to be untouched; got %v", field, entry[field])
+		}
+
+		remappedKey := fmt.Sprintf("fields.%s", field)
+		if remapped, ok := entry[remappedKey]; ok {
+			t.Errorf("Expected %s to be empty; got %v", remappedKey, remapped)
+		}
+	}
+
+	for _, field := range []string{"@timestamp", "@level", "@message"} {
+		if entry[field] == field {
+			t.Errorf("Expected field %v to be mapped to an Entry value", field)
+		}
+
+		remappedKey := fmt.Sprintf("fields.%s", field)
+		if remapped, ok := entry[remappedKey]; ok {
+			if remapped != field {
+				t.Errorf("Expected field %v to be copied to %s; got %v", field, remappedKey, remapped)
+			}
+		} else {
+			t.Errorf("Expected field %v to be copied to %s; was absent", field, remappedKey)
+		}
+	}
+}
+
+func TestFieldsInNestedDictionary(t *testing.T) {
+	formatter := &JSONFormatter{
+		DataKey: "args",
+	}
+
+	logEntry := WithFields(Fields{
+		"level": "level",
+		"test":  "test",
+	})
+	logEntry.Level = InfoLevel
+
+	b, err := formatter.Format(logEntry)
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+
+	entry := make(map[string]interface{})
+	err = json.Unmarshal(b, &entry)
+	if err != nil {
+		t.Fatal("Unable to unmarshal formatted entry: ", err)
+	}
+
+	args := entry["args"].(map[string]interface{})
+
+	for _, field := range []string{"test", "level"} {
+		if value, present := args[field]; !present || value != field {
+			t.Errorf("Expected field %v to be present under 'args'; untouched", field)
+		}
+	}
+
+	for _, field := range []string{"test", "fields.level"} {
+		if _, present := entry[field]; present {
+			t.Errorf("Expected field %v not to be present at top level", field)
+		}
+	}
+
+	// with nested object, "level" shouldn't clash
+	if entry["level"] != "info" {
+		t.Errorf("Expected 'level' field to contain 'info'")
+	}
+}
+
+func TestJSONEntryEndsWithNewline(t *testing.T) {
+	formatter := &JSONFormatter{}
+
+	b, err := formatter.Format(WithField("level", "something"))
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+
+	if b[len(b)-1] != '\n' {
+		t.Fatal("Expected JSON log entry to end with a newline")
+	}
+}
+
+func TestJSONMessageKey(t *testing.T) {
+	formatter := &JSONFormatter{
+		FieldMap: FieldMap{
+			FieldKeyMsg: "message",
+		},
+	}
+
+	b, err := formatter.Format(&Entry{Message: "oh hai"})
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+	s := string(b)
+	if !(strings.Contains(s, "message") && strings.Contains(s, "oh hai")) {
+		t.Fatal("Expected JSON to format message key")
+	}
+}
+
+func TestJSONLevelKey(t *testing.T) {
+	formatter := &JSONFormatter{
+		FieldMap: FieldMap{
+			FieldKeyLevel: "somelevel",
+		},
+	}
+
+	b, err := formatter.Format(WithField("level", "something"))
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+	s := string(b)
+	if !strings.Contains(s, "somelevel") {
+		t.Fatal("Expected JSON to format level key")
+	}
+}
+
+func TestJSONTimeKey(t *testing.T) {
+	formatter := &JSONFormatter{
+		FieldMap: FieldMap{
+			FieldKeyTime: "timeywimey",
+		},
+	}
+
+	b, err := formatter.Format(WithField("level", "something"))
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+	s := string(b)
+	if !strings.Contains(s, "timeywimey") {
+		t.Fatal("Expected JSON to format time key")
+	}
+}
+
+func TestFieldDoesNotClashWithCaller(t *testing.T) {
+	SetReportCaller(false)
+	formatter := &JSONFormatter{}
+
+	b, err := formatter.Format(WithField("func", "howdy pardner"))
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+
+	entry := make(map[string]interface{})
+	err = json.Unmarshal(b, &entry)
+	if err != nil {
+		t.Fatal("Unable to unmarshal formatted entry: ", err)
+	}
+
+	if entry["func"] != "howdy pardner" {
+		t.Fatal("func field replaced when ReportCaller=false")
+	}
+}
+
+func TestFieldClashWithCaller(t *testing.T) {
+	SetReportCaller(true)
+	formatter := &JSONFormatter{}
+	e := WithField("func", "howdy pardner")
+	e.Caller = &runtime.Frame{Function: "somefunc"}
+	b, err := formatter.Format(e)
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+
+	entry := make(map[string]interface{})
+	err = json.Unmarshal(b, &entry)
+	if err != nil {
+		t.Fatal("Unable to unmarshal formatted entry: ", err)
+	}
+
+	if entry["fields.func"] != "howdy pardner" {
+		t.Fatalf("fields.func not set to original func field when ReportCaller=true (got '%s')",
+			entry["fields.func"])
+	}
+
+	if entry["func"] != "somefunc" {
+		t.Fatalf("func not set as expected when ReportCaller=true (got '%s')",
+			entry["func"])
+	}
+
+	SetReportCaller(false) // return to default value
+}
+
+func TestJSONDisableTimestamp(t *testing.T) {
+	formatter := &JSONFormatter{
+		DisableTimestamp: true,
+	}
+
+	b, err := formatter.Format(WithField("level", "something"))
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+	s := string(b)
+	if strings.Contains(s, FieldKeyTime) {
+		t.Error("Did not prevent timestamp", s)
+	}
+}
+
+func TestJSONEnableTimestamp(t *testing.T) {
+	formatter := &JSONFormatter{}
+
+	b, err := formatter.Format(WithField("level", "something"))
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+	s := string(b)
+	if !strings.Contains(s, FieldKeyTime) {
+		t.Error("Timestamp not present", s)
+	}
+}
+
+func TestJSONDisableHTMLEscape(t *testing.T) {
+	formatter := &JSONFormatter{DisableHTMLEscape: true}
+
+	b, err := formatter.Format(&Entry{Message: "& < >"})
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+	s := string(b)
+	if !strings.Contains(s, "& < >") {
+		t.Error("Message should not be HTML escaped", s)
+	}
+}
+
+func TestJSONEnableHTMLEscape(t *testing.T) {
+	formatter := &JSONFormatter{}
+
+	b, err := formatter.Format(&Entry{Message: "& < >"})
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+	s := string(b)
+	if !(strings.Contains(s, "u0026") && strings.Contains(s, "u003e") && strings.Contains(s, "u003c")) {
+		t.Error("Message should be HTML escaped", s)
+	}
+}

level_test.go

@@ -0,0 +1,62 @@
+package logrus_test
+
+import (
+	"bytes"
+	"encoding/json"
+	"testing"
+
+	"git.internal/re/logrus"
+	"github.com/stretchr/testify/require"
+)
+
+func TestLevelJsonEncoding(t *testing.T) {
+	type X struct {
+		Level logrus.Level
+	}
+
+	var x X
+	x.Level = logrus.WarnLevel
+	var buf bytes.Buffer
+	enc := json.NewEncoder(&buf)
+	require.NoError(t, enc.Encode(x))
+	dec := json.NewDecoder(&buf)
+	var y X
+	require.NoError(t, dec.Decode(&y))
+}
+
+func TestLevelUnmarshalText(t *testing.T) {
+	var u logrus.Level
+	for _, level := range logrus.AllLevels {
+		t.Run(level.String(), func(t *testing.T) {
+			require.NoError(t, u.UnmarshalText([]byte(level.String())))
+			require.Equal(t, level, u)
+		})
+	}
+	t.Run("invalid", func(t *testing.T) {
+		require.Error(t, u.UnmarshalText([]byte("invalid")))
+	})
+}
+
+func TestLevelMarshalText(t *testing.T) {
+	levelStrings := []string{
+		"panic",
+		"fatal",
+		"error",
+		"warning",
+		"info",
+		"debug",
+		"trace",
+	}
+	for idx, val := range logrus.AllLevels {
+		level := val
+		t.Run(level.String(), func(t *testing.T) {
+			var cmp logrus.Level
+			b, err := level.MarshalText()
+			require.NoError(t, err)
+			require.Equal(t, levelStrings[idx], string(b))
+			err = cmp.UnmarshalText(b)
+			require.NoError(t, err)
+			require.Equal(t, level, cmp)
+		})
+	}
+}

logger.go

@@ -1,20 +1,28 @@
 package logrus
 
 import (
+	"context"
 	"io"
 	"os"
 	"sync"
+	"sync/atomic"
+	"time"
 )
 
+// LogFunction For big messages, it can be more efficient to pass a function
+// and only call it if the log level is actually enables rather than
+// generating the log message and then checking if the level is enabled
+type LogFunction func() []interface{}
+
 type Logger struct {
 	// The logs are `io.Copy`'d to this in a mutex. It's common to set this to a
-	// file, or leave it default which is `os.Stdout`. You can also set this to
+	// file, or leave it default which is `os.Stderr`. You can also set this to
-	// something more adventorous, such as logging to Kafka.
+	// something more adventurous, such as logging to Kafka.
 	Out io.Writer
 	// Hooks for the logger instance. These allow firing events based on logging
 	// levels and log entries. For example, to send errors to an error tracking
 	// service, log to StatsD or dump the core on fatal errors.
-	Hooks levelHooks
+	Hooks LevelHooks
 	// All log entries pass through the formatter before logged to Out. The
 	// included formatters are `TextFormatter` and `JSONFormatter` for which
 	// TextFormatter is the default. In development (when a TTY is attached) it
@@ -22,140 +30,388 @@ type Logger struct {
 	// own that implements the `Formatter` interface, see the `README` or included
 	// formatters for examples.
 	Formatter Formatter
+
+	// Flag for whether to log caller info (off by default)
+	ReportCaller bool
+
 	// The logging level the logger should log at. This is typically (and defaults
 	// to) `logrus.Info`, which allows Info(), Warn(), Error() and Fatal() to be
-	// logged. `logrus.Debug` is useful in
+	// logged.
 	Level Level
-	// Used to sync writing to the log.
+	// Used to sync writing to the log. Locking is enabled by Default
-	mu sync.Mutex
+	mu MutexWrap
+	// Reusable empty entry
+	entryPool sync.Pool
+	// Function to exit the application, defaults to `os.Exit()`
+	ExitFunc exitFunc
+	// The buffer pool used to format the log. If it is nil, the default global
+	// buffer pool will be used.
+	BufferPool BufferPool
+}
+
+type exitFunc func(int)
+
+type MutexWrap struct {
+	lock     sync.Mutex
+	disabled bool
+}
+
+func (mw *MutexWrap) Lock() {
+	if !mw.disabled {
+		mw.lock.Lock()
+	}
+}
+
+func (mw *MutexWrap) Unlock() {
+	if !mw.disabled {
+		mw.lock.Unlock()
+	}
+}
+
+func (mw *MutexWrap) Disable() {
+	mw.disabled = true
 }
 
 // Creates a new logger. Configuration should be set by changing `Formatter`,
 // `Out` and `Hooks` directly on the default logger instance. You can also just
 // instantiate your own:
 //
-//    var log = &Logger{
+//    var log = &logrus.Logger{
 //      Out: os.Stderr,
-//      Formatter: new(JSONFormatter),
+//      Formatter: new(logrus.TextFormatter),
-//      Hooks: make(levelHooks),
+//      Hooks: make(logrus.LevelHooks),
 //      Level: logrus.DebugLevel,
 //    }
 //
 // It's recommended to make this a global instance called `log`.
 func New() *Logger {
 	return &Logger{
-		Out:       os.Stdout,
+		Out:          os.Stderr,
-		Formatter: new(TextFormatter),
+		Formatter:    new(TextFormatter),
-		Hooks:     make(levelHooks),
+		Hooks:        make(LevelHooks),
-		Level:     InfoLevel,
+		Level:        InfoLevel,
+		ExitFunc:     os.Exit,
+		ReportCaller: false,
 	}
 }
 
-// Adds a field to the log entry, note that you it doesn't log until you call
+func (logger *Logger) newEntry() *Entry {
-// Debug, Print, Info, Warn, Fatal or Panic. It only creates a log entry.
+	entry, ok := logger.entryPool.Get().(*Entry)
-// Ff you want multiple fields, use `WithFields`.
+	if ok {
+		return entry
+	}
+	return NewEntry(logger)
+}
+
+func (logger *Logger) releaseEntry(entry *Entry) {
+	entry.Data = map[string]interface{}{}
+	logger.entryPool.Put(entry)
+}
+
+// WithField allocates a new entry and adds a field to it.
+// Debug, Print, Info, Warn, Error, Fatal or Panic must be then applied to
+// this new returned entry.
+// If you want multiple fields, use `WithFields`.
 func (logger *Logger) WithField(key string, value interface{}) *Entry {
-	return NewEntry(logger).WithField(key, value)
+	entry := logger.newEntry()
+	defer logger.releaseEntry(entry)
+	return entry.WithField(key, value)
 }
 
 // Adds a struct of fields to the log entry. All it does is call `WithField` for
 // each `Field`.
 func (logger *Logger) WithFields(fields Fields) *Entry {
-	return NewEntry(logger).WithFields(fields)
+	entry := logger.newEntry()
+	defer logger.releaseEntry(entry)
+	return entry.WithFields(fields)
+}
+
+// Add an error as single field to the log entry.  All it does is call
+// `WithError` for the given `error`.
+func (logger *Logger) WithError(err error) *Entry {
+	entry := logger.newEntry()
+	defer logger.releaseEntry(entry)
+	return entry.WithError(err)
+}
+
+// Add a context to the log entry.
+func (logger *Logger) WithContext(ctx context.Context) *Entry {
+	entry := logger.newEntry()
+	defer logger.releaseEntry(entry)
+	return entry.WithContext(ctx)
+}
+
+// Overrides the time of the log entry.
+func (logger *Logger) WithTime(t time.Time) *Entry {
+	entry := logger.newEntry()
+	defer logger.releaseEntry(entry)
+	return entry.WithTime(t)
+}
+
+func (logger *Logger) Logf(level Level, format string, args ...interface{}) {
+	if logger.IsLevelEnabled(level) {
+		entry := logger.newEntry()
+		entry.Logf(level, format, args...)
+		logger.releaseEntry(entry)
+	}
+}
+
+func (logger *Logger) Tracef(format string, args ...interface{}) {
+	logger.Logf(TraceLevel, format, args...)
 }
 
 func (logger *Logger) Debugf(format string, args ...interface{}) {
-	NewEntry(logger).Debugf(format, args...)
+	logger.Logf(DebugLevel, format, args...)
 }
 
 func (logger *Logger) Infof(format string, args ...interface{}) {
-	NewEntry(logger).Infof(format, args...)
+	logger.Logf(InfoLevel, format, args...)
 }
 
 func (logger *Logger) Printf(format string, args ...interface{}) {
-	NewEntry(logger).Printf(format, args...)
+	entry := logger.newEntry()
+	entry.Printf(format, args...)
+	logger.releaseEntry(entry)
 }
 
 func (logger *Logger) Warnf(format string, args ...interface{}) {
-	NewEntry(logger).Warnf(format, args...)
+	logger.Logf(WarnLevel, format, args...)
 }
 
 func (logger *Logger) Warningf(format string, args ...interface{}) {
-	NewEntry(logger).Warnf(format, args...)
+	logger.Warnf(format, args...)
 }
 
 func (logger *Logger) Errorf(format string, args ...interface{}) {
-	NewEntry(logger).Errorf(format, args...)
+	logger.Logf(ErrorLevel, format, args...)
 }
 
 func (logger *Logger) Fatalf(format string, args ...interface{}) {
-	NewEntry(logger).Fatalf(format, args...)
+	logger.Logf(FatalLevel, format, args...)
+	logger.Exit(1)
 }
 
 func (logger *Logger) Panicf(format string, args ...interface{}) {
-	NewEntry(logger).Panicf(format, args...)
+	logger.Logf(PanicLevel, format, args...)
+}
+
+// Log will log a message at the level given as parameter.
+// Warning: using Log at Panic or Fatal level will not respectively Panic nor Exit.
+// For this behaviour Logger.Panic or Logger.Fatal should be used instead.
+func (logger *Logger) Log(level Level, args ...interface{}) {
+	if logger.IsLevelEnabled(level) {
+		entry := logger.newEntry()
+		entry.Log(level, args...)
+		logger.releaseEntry(entry)
+	}
+}
+
+func (logger *Logger) LogFn(level Level, fn LogFunction) {
+	if logger.IsLevelEnabled(level) {
+		entry := logger.newEntry()
+		entry.Log(level, fn()...)
+		logger.releaseEntry(entry)
+	}
+}
+
+func (logger *Logger) Trace(args ...interface{}) {
+	logger.Log(TraceLevel, args...)
 }
 
 func (logger *Logger) Debug(args ...interface{}) {
-	NewEntry(logger).Debug(args...)
+	logger.Log(DebugLevel, args...)
 }
 
 func (logger *Logger) Info(args ...interface{}) {
-	NewEntry(logger).Info(args...)
+	logger.Log(InfoLevel, args...)
 }
 
 func (logger *Logger) Print(args ...interface{}) {
-	NewEntry(logger).Info(args...)
+	entry := logger.newEntry()
+	entry.Print(args...)
+	logger.releaseEntry(entry)
 }
 
 func (logger *Logger) Warn(args ...interface{}) {
-	NewEntry(logger).Warn(args...)
+	logger.Log(WarnLevel, args...)
 }
 
 func (logger *Logger) Warning(args ...interface{}) {
-	NewEntry(logger).Warn(args...)
+	logger.Warn(args...)
 }
 
 func (logger *Logger) Error(args ...interface{}) {
-	NewEntry(logger).Error(args...)
+	logger.Log(ErrorLevel, args...)
 }
 
 func (logger *Logger) Fatal(args ...interface{}) {
-	NewEntry(logger).Fatal(args...)
+	logger.Log(FatalLevel, args...)
+	logger.Exit(1)
 }
 
 func (logger *Logger) Panic(args ...interface{}) {
-	NewEntry(logger).Panic(args...)
+	logger.Log(PanicLevel, args...)
+}
+
+func (logger *Logger) TraceFn(fn LogFunction) {
+	logger.LogFn(TraceLevel, fn)
+}
+
+func (logger *Logger) DebugFn(fn LogFunction) {
+	logger.LogFn(DebugLevel, fn)
+}
+
+func (logger *Logger) InfoFn(fn LogFunction) {
+	logger.LogFn(InfoLevel, fn)
+}
+
+func (logger *Logger) PrintFn(fn LogFunction) {
+	entry := logger.newEntry()
+	entry.Print(fn()...)
+	logger.releaseEntry(entry)
+}
+
+func (logger *Logger) WarnFn(fn LogFunction) {
+	logger.LogFn(WarnLevel, fn)
+}
+
+func (logger *Logger) WarningFn(fn LogFunction) {
+	logger.WarnFn(fn)
+}
+
+func (logger *Logger) ErrorFn(fn LogFunction) {
+	logger.LogFn(ErrorLevel, fn)
+}
+
+func (logger *Logger) FatalFn(fn LogFunction) {
+	logger.LogFn(FatalLevel, fn)
+	logger.Exit(1)
+}
+
+func (logger *Logger) PanicFn(fn LogFunction) {
+	logger.LogFn(PanicLevel, fn)
+}
+
+func (logger *Logger) Logln(level Level, args ...interface{}) {
+	if logger.IsLevelEnabled(level) {
+		entry := logger.newEntry()
+		entry.Logln(level, args...)
+		logger.releaseEntry(entry)
+	}
+}
+
+func (logger *Logger) Traceln(args ...interface{}) {
+	logger.Logln(TraceLevel, args...)
 }
 
 func (logger *Logger) Debugln(args ...interface{}) {
-	NewEntry(logger).Debugln(args...)
+	logger.Logln(DebugLevel, args...)
 }
 
 func (logger *Logger) Infoln(args ...interface{}) {
-	NewEntry(logger).Infoln(args...)
+	logger.Logln(InfoLevel, args...)
 }
 
 func (logger *Logger) Println(args ...interface{}) {
-	NewEntry(logger).Println(args...)
+	entry := logger.newEntry()
+	entry.Println(args...)
+	logger.releaseEntry(entry)
 }
 
 func (logger *Logger) Warnln(args ...interface{}) {
-	NewEntry(logger).Warnln(args...)
+	logger.Logln(WarnLevel, args...)
 }
 
 func (logger *Logger) Warningln(args ...interface{}) {
-	NewEntry(logger).Warnln(args...)
+	logger.Warnln(args...)
 }
 
 func (logger *Logger) Errorln(args ...interface{}) {
-	NewEntry(logger).Errorln(args...)
+	logger.Logln(ErrorLevel, args...)
 }
 
 func (logger *Logger) Fatalln(args ...interface{}) {
-	NewEntry(logger).Fatalln(args...)
+	logger.Logln(FatalLevel, args...)
+	logger.Exit(1)
 }
 
 func (logger *Logger) Panicln(args ...interface{}) {
-	NewEntry(logger).Panicln(args...)
+	logger.Logln(PanicLevel, args...)
+}
+
+func (logger *Logger) Exit(code int) {
+	runHandlers()
+	if logger.ExitFunc == nil {
+		logger.ExitFunc = os.Exit
+	}
+	logger.ExitFunc(code)
+}
+
+//When file is opened with appending mode, it's safe to
+//write concurrently to a file (within 4k message on Linux).
+//In these cases user can choose to disable the lock.
+func (logger *Logger) SetNoLock() {
+	logger.mu.Disable()
+}
+
+func (logger *Logger) level() Level {
+	return Level(atomic.LoadUint32((*uint32)(&logger.Level)))
+}
+
+// SetLevel sets the logger level.
+func (logger *Logger) SetLevel(level Level) {
+	atomic.StoreUint32((*uint32)(&logger.Level), uint32(level))
+}
+
+// GetLevel returns the logger level.
+func (logger *Logger) GetLevel() Level {
+	return logger.level()
+}
+
+// AddHook adds a hook to the logger hooks.
+func (logger *Logger) AddHook(hook Hook) {
+	logger.mu.Lock()
+	defer logger.mu.Unlock()
+	logger.Hooks.Add(hook)
+}
+
+// IsLevelEnabled checks if the log level of the logger is greater than the level param
+func (logger *Logger) IsLevelEnabled(level Level) bool {
+	return logger.level() >= level
+}
+
+// SetFormatter sets the logger formatter.
+func (logger *Logger) SetFormatter(formatter Formatter) {
+	logger.mu.Lock()
+	defer logger.mu.Unlock()
+	logger.Formatter = formatter
+}
+
+// SetOutput sets the logger output.
+func (logger *Logger) SetOutput(output io.Writer) {
+	logger.mu.Lock()
+	defer logger.mu.Unlock()
+	logger.Out = output
+}
+
+func (logger *Logger) SetReportCaller(reportCaller bool) {
+	logger.mu.Lock()
+	defer logger.mu.Unlock()
+	logger.ReportCaller = reportCaller
+}
+
+// ReplaceHooks replaces the logger hooks and returns the old ones
+func (logger *Logger) ReplaceHooks(hooks LevelHooks) LevelHooks {
+	logger.mu.Lock()
+	oldHooks := logger.Hooks
+	logger.Hooks = hooks
+	logger.mu.Unlock()
+	return oldHooks
+}
+
+// SetBufferPool sets the logger buffer pool.
+func (logger *Logger) SetBufferPool(pool BufferPool) {
+	logger.mu.Lock()
+	defer logger.mu.Unlock()
+	logger.BufferPool = pool
 }

logger_bench_test.go

@@ -0,0 +1,77 @@
+package logrus
+
+import (
+	"io/ioutil"
+	"os"
+	"testing"
+)
+
+func BenchmarkDummyLogger(b *testing.B) {
+	nullf, err := os.OpenFile("/dev/null", os.O_WRONLY, 0666)
+	if err != nil {
+		b.Fatalf("%v", err)
+	}
+	defer nullf.Close()
+	doLoggerBenchmark(b, nullf, &TextFormatter{DisableColors: true}, smallFields)
+}
+
+func BenchmarkDummyLoggerNoLock(b *testing.B) {
+	nullf, err := os.OpenFile("/dev/null", os.O_WRONLY|os.O_APPEND, 0666)
+	if err != nil {
+		b.Fatalf("%v", err)
+	}
+	defer nullf.Close()
+	doLoggerBenchmarkNoLock(b, nullf, &TextFormatter{DisableColors: true}, smallFields)
+}
+
+func doLoggerBenchmark(b *testing.B, out *os.File, formatter Formatter, fields Fields) {
+	logger := Logger{
+		Out:       out,
+		Level:     InfoLevel,
+		Formatter: formatter,
+	}
+	entry := logger.WithFields(fields)
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			entry.Info("aaa")
+		}
+	})
+}
+
+func doLoggerBenchmarkNoLock(b *testing.B, out *os.File, formatter Formatter, fields Fields) {
+	logger := Logger{
+		Out:       out,
+		Level:     InfoLevel,
+		Formatter: formatter,
+	}
+	logger.SetNoLock()
+	entry := logger.WithFields(fields)
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			entry.Info("aaa")
+		}
+	})
+}
+
+func BenchmarkLoggerJSONFormatter(b *testing.B) {
+	doLoggerBenchmarkWithFormatter(b, &JSONFormatter{})
+}
+
+func BenchmarkLoggerTextFormatter(b *testing.B) {
+	doLoggerBenchmarkWithFormatter(b, &TextFormatter{})
+}
+
+func doLoggerBenchmarkWithFormatter(b *testing.B, f Formatter) {
+	b.SetParallelism(100)
+	log := New()
+	log.Formatter = f
+	log.Out = ioutil.Discard
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			log.
+				WithField("foo1", "bar1").
+				WithField("foo2", "bar2").
+				Info("this is a dummy log")
+		}
+	})
+}

logger_test.go

@@ -0,0 +1,97 @@
+package logrus
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestFieldValueError(t *testing.T) {
+	buf := &bytes.Buffer{}
+	l := &Logger{
+		Out:       buf,
+		Formatter: new(JSONFormatter),
+		Hooks:     make(LevelHooks),
+		Level:     DebugLevel,
+	}
+	l.WithField("func", func() {}).Info("test")
+	fmt.Println(buf.String())
+	var data map[string]interface{}
+	if err := json.Unmarshal(buf.Bytes(), &data); err != nil {
+		t.Error("unexpected error", err)
+	}
+	_, ok := data[FieldKeyLogrusError]
+	require.True(t, ok, `cannot found expected "logrus_error" field: %v`, data)
+}
+
+func TestNoFieldValueError(t *testing.T) {
+	buf := &bytes.Buffer{}
+	l := &Logger{
+		Out:       buf,
+		Formatter: new(JSONFormatter),
+		Hooks:     make(LevelHooks),
+		Level:     DebugLevel,
+	}
+	l.WithField("str", "str").Info("test")
+	fmt.Println(buf.String())
+	var data map[string]interface{}
+	if err := json.Unmarshal(buf.Bytes(), &data); err != nil {
+		t.Error("unexpected error", err)
+	}
+	_, ok := data[FieldKeyLogrusError]
+	require.False(t, ok)
+}
+
+func TestWarninglnNotEqualToWarning(t *testing.T) {
+	buf := &bytes.Buffer{}
+	bufln := &bytes.Buffer{}
+
+	formatter := new(TextFormatter)
+	formatter.DisableTimestamp = true
+	formatter.DisableLevelTruncation = true
+
+	l := &Logger{
+		Out:       buf,
+		Formatter: formatter,
+		Hooks:     make(LevelHooks),
+		Level:     DebugLevel,
+	}
+	l.Warning("hello,", "world")
+
+	l.SetOutput(bufln)
+	l.Warningln("hello,", "world")
+
+	assert.NotEqual(t, buf.String(), bufln.String(), "Warning() and Wantingln() should not be equal")
+}
+
+type testBufferPool struct {
+	buffers []*bytes.Buffer
+	get int
+}
+
+func (p *testBufferPool) Get() *bytes.Buffer {
+	p.get++
+	return new(bytes.Buffer)
+}
+
+func (p *testBufferPool) Put(buf *bytes.Buffer) {
+	p.buffers = append(p.buffers, buf)
+}
+
+func TestLogger_SetBufferPool(t *testing.T) {
+	out := &bytes.Buffer{}
+	l := New()
+	l.SetOutput(out)
+
+	pool := new(testBufferPool)
+	l.SetBufferPool(pool)
+
+	l.Info("test")
+
+	assert.Equal(t, pool.get, 1, "Logger.SetBufferPool(): The BufferPool.Get() must be called")
+	assert.Len(t, pool.buffers, 1, "Logger.SetBufferPool(): The BufferPool.Put() must be called")
+}

logrus.go

@@ -3,37 +3,27 @@ package logrus
 import (
 	"fmt"
 	"log"
+	"strings"
 )
 
 // Fields type, used to pass to `WithFields`.
 type Fields map[string]interface{}
 
 // Level type
-type Level uint8
+type Level uint32
 
 // Convert the Level to a string. E.g. PanicLevel becomes "panic".
 func (level Level) String() string {
-	switch level {
+	if b, err := level.MarshalText(); err == nil {
-	case DebugLevel:
+		return string(b)
-		return "debug"
+	} else {
-	case InfoLevel:
+		return "unknown"
-		return "info"
-	case WarnLevel:
-		return "warning"
-	case ErrorLevel:
-		return "error"
-	case FatalLevel:
-		return "fatal"
-	case PanicLevel:
-		return "panic"
 	}
-
-	return "unknown"
 }
 
 // ParseLevel takes a string level and returns the Logrus log level constant.
 func ParseLevel(lvl string) (Level, error) {
-	switch lvl {
+	switch strings.ToLower(lvl) {
 	case "panic":
 		return PanicLevel, nil
 	case "fatal":
@@ -46,19 +36,65 @@ func ParseLevel(lvl string) (Level, error) {
 		return InfoLevel, nil
 	case "debug":
 		return DebugLevel, nil
+	case "trace":
+		return TraceLevel, nil
 	}
 
 	var l Level
 	return l, fmt.Errorf("not a valid logrus Level: %q", lvl)
 }
 
+// UnmarshalText implements encoding.TextUnmarshaler.
+func (level *Level) UnmarshalText(text []byte) error {
+	l, err := ParseLevel(string(text))
+	if err != nil {
+		return err
+	}
+
+	*level = l
+
+	return nil
+}
+
+func (level Level) MarshalText() ([]byte, error) {
+	switch level {
+	case TraceLevel:
+		return []byte("trace"), nil
+	case DebugLevel:
+		return []byte("debug"), nil
+	case InfoLevel:
+		return []byte("info"), nil
+	case WarnLevel:
+		return []byte("warning"), nil
+	case ErrorLevel:
+		return []byte("error"), nil
+	case FatalLevel:
+		return []byte("fatal"), nil
+	case PanicLevel:
+		return []byte("panic"), nil
+	}
+
+	return nil, fmt.Errorf("not a valid logrus level %d", level)
+}
+
+// A constant exposing all logging levels
+var AllLevels = []Level{
+	PanicLevel,
+	FatalLevel,
+	ErrorLevel,
+	WarnLevel,
+	InfoLevel,
+	DebugLevel,
+	TraceLevel,
+}
+
 // These are the different logging levels. You can set the logging level to log
 // on your instance of logger, obtained with `logrus.New()`.
 const (
 	// PanicLevel level, highest level of severity. Logs and then calls panic with the
 	// message passed to Debug, Info, ...
 	PanicLevel Level = iota
-	// FatalLevel level. Logs and then calls `os.Exit(1)`. It will exit even if the
+	// FatalLevel level. Logs and then calls `logger.Exit(1)`. It will exit even if the
 	// logging level is set to Panic.
 	FatalLevel
 	// ErrorLevel level. Logs. Used for errors that should definitely be noted.
@@ -71,10 +107,16 @@ const (
 	InfoLevel
 	// DebugLevel level. Usually only enabled when debugging. Very verbose logging.
 	DebugLevel
+	// TraceLevel level. Designates finer-grained informational events than the Debug.
+	TraceLevel
 )
 
 // Won't compile if StdLogger can't be realized by a log.Logger
-var _ StdLogger = &log.Logger{}
+var (
+	_ StdLogger = &log.Logger{}
+	_ StdLogger = &Entry{}
+	_ StdLogger = &Logger{}
+)
 
 // StdLogger is what your logrus-enabled library should take, that way
 // it'll accept a stdlib logger and a logrus logger. There's no standard
@@ -92,3 +134,53 @@ type StdLogger interface {
 	Panicf(string, ...interface{})
 	Panicln(...interface{})
 }
+
+// The FieldLogger interface generalizes the Entry and Logger types
+type FieldLogger interface {
+	WithField(key string, value interface{}) *Entry
+	WithFields(fields Fields) *Entry
+	WithError(err error) *Entry
+
+	Debugf(format string, args ...interface{})
+	Infof(format string, args ...interface{})
+	Printf(format string, args ...interface{})
+	Warnf(format string, args ...interface{})
+	Warningf(format string, args ...interface{})
+	Errorf(format string, args ...interface{})
+	Fatalf(format string, args ...interface{})
+	Panicf(format string, args ...interface{})
+
+	Debug(args ...interface{})
+	Info(args ...interface{})
+	Print(args ...interface{})
+	Warn(args ...interface{})
+	Warning(args ...interface{})
+	Error(args ...interface{})
+	Fatal(args ...interface{})
+	Panic(args ...interface{})
+
+	Debugln(args ...interface{})
+	Infoln(args ...interface{})
+	Println(args ...interface{})
+	Warnln(args ...interface{})
+	Warningln(args ...interface{})
+	Errorln(args ...interface{})
+	Fatalln(args ...interface{})
+	Panicln(args ...interface{})
+
+	// IsDebugEnabled() bool
+	// IsInfoEnabled() bool
+	// IsWarnEnabled() bool
+	// IsErrorEnabled() bool
+	// IsFatalEnabled() bool
+	// IsPanicEnabled() bool
+}
+
+// Ext1FieldLogger (the first extension to FieldLogger) is superfluous, it is
+// here for consistancy. Do not use. Use Logger or Entry instead.
+type Ext1FieldLogger interface {
+	FieldLogger
+	Tracef(format string, args ...interface{})
+	Trace(args ...interface{})
+	Traceln(args ...interface{})
+}

logrus_test.go

@@ -1,66 +1,117 @@
-package logrus
+package logrus_test
 
 import (
 	"bytes"
 	"encoding/json"
-	"strconv"
+	"fmt"
-	"strings"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"runtime"
+	"sync"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	. "git.internal/re/logrus"
+	. "git.internal/re/logrus/internal/testutils"
 )
 
-func LogAndAssertJSON(t *testing.T, log func(*Logger), assertions func(fields Fields)) {
+// TestReportCaller verifies that when ReportCaller is set, the 'func' field
+// is added, and when it is unset it is not set or modified
+// Verify that functions within the Logrus package aren't considered when
+// discovering the caller.
+func TestReportCallerWhenConfigured(t *testing.T) {
+	LogAndAssertJSON(t, func(log *Logger) {
+		log.ReportCaller = false
+		log.Print("testNoCaller")
+	}, func(fields Fields) {
+		assert.Equal(t, "testNoCaller", fields["msg"])
+		assert.Equal(t, "info", fields["level"])
+		assert.Equal(t, nil, fields["func"])
+	})
+
+	LogAndAssertJSON(t, func(log *Logger) {
+		log.ReportCaller = true
+		log.Print("testWithCaller")
+	}, func(fields Fields) {
+		assert.Equal(t, "testWithCaller", fields["msg"])
+		assert.Equal(t, "info", fields["level"])
+		assert.Equal(t,
+			"git.internal/re/logrus_test.TestReportCallerWhenConfigured.func3", fields[FieldKeyFunc])
+	})
+
+	LogAndAssertJSON(t, func(log *Logger) {
+		log.ReportCaller = true
+		log.Formatter.(*JSONFormatter).CallerPrettyfier = func(f *runtime.Frame) (string, string) {
+			return "somekindoffunc", "thisisafilename"
+		}
+		log.Print("testWithCallerPrettyfier")
+	}, func(fields Fields) {
+		assert.Equal(t, "somekindoffunc", fields[FieldKeyFunc])
+		assert.Equal(t, "thisisafilename", fields[FieldKeyFile])
+	})
+
+	LogAndAssertText(t, func(log *Logger) {
+		log.ReportCaller = true
+		log.Formatter.(*TextFormatter).CallerPrettyfier = func(f *runtime.Frame) (string, string) {
+			return "somekindoffunc", "thisisafilename"
+		}
+		log.Print("testWithCallerPrettyfier")
+	}, func(fields map[string]string) {
+		assert.Equal(t, "somekindoffunc", fields[FieldKeyFunc])
+		assert.Equal(t, "thisisafilename", fields[FieldKeyFile])
+	})
+}
+
+func logSomething(t *testing.T, message string) Fields {
 	var buffer bytes.Buffer
 	var fields Fields
 
 	logger := New()
 	logger.Out = &buffer
 	logger.Formatter = new(JSONFormatter)
+	logger.ReportCaller = true
 
-	log(logger)
+	entry := logger.WithFields(Fields{
+		"foo": "bar",
+	})
+
+	entry.Info(message)
 
 	err := json.Unmarshal(buffer.Bytes(), &fields)
 	assert.Nil(t, err)
 
-	assertions(fields)
+	return fields
 }
 
-func LogAndAssertText(t *testing.T, log func(*Logger), assertions func(fields map[string]string)) {
+// TestReportCallerHelperDirect - verify reference when logging from a regular function
-	var buffer bytes.Buffer
+func TestReportCallerHelperDirect(t *testing.T) {
+	fields := logSomething(t, "direct")
 
-	logger := New()
+	assert.Equal(t, "direct", fields["msg"])
-	logger.Out = &buffer
+	assert.Equal(t, "info", fields["level"])
-	logger.Formatter = &TextFormatter{
+	assert.Regexp(t, "github.com/.*/logrus_test.logSomething", fields["func"])
-		DisableColors: true,
+}
-	}
 
-	log(logger)
+// TestReportCallerHelperDirect - verify reference when logging from a function called via pointer
+func TestReportCallerHelperViaPointer(t *testing.T) {
+	fptr := logSomething
+	fields := fptr(t, "via pointer")
 
-	fields := make(map[string]string)
+	assert.Equal(t, "via pointer", fields["msg"])
-	for _, kv := range strings.Split(buffer.String(), " ") {
+	assert.Equal(t, "info", fields["level"])
-		if !strings.Contains(kv, "=") {
+	assert.Regexp(t, "github.com/.*/logrus_test.logSomething", fields["func"])
-			continue
-		}
-		kvArr := strings.Split(kv, "=")
-		key := strings.TrimSpace(kvArr[0])
-		val := kvArr[1]
-		if kvArr[1][0] == '"' {
-			var err error
-			val, err = strconv.Unquote(val)
-			assert.NoError(t, err)
-		}
-		fields[key] = val
-	}
-	assertions(fields)
 }
 
 func TestPrint(t *testing.T) {
 	LogAndAssertJSON(t, func(log *Logger) {
 		log.Print("test")
 	}, func(fields Fields) {
-		assert.Equal(t, fields["msg"], "test")
+		assert.Equal(t, "test", fields["msg"])
-		assert.Equal(t, fields["level"], "info")
+		assert.Equal(t, "info", fields["level"])
 	})
 }
 
@@ -68,8 +119,8 @@ func TestInfo(t *testing.T) {
 	LogAndAssertJSON(t, func(log *Logger) {
 		log.Info("test")
 	}, func(fields Fields) {
-		assert.Equal(t, fields["msg"], "test")
+		assert.Equal(t, "test", fields["msg"])
-		assert.Equal(t, fields["level"], "info")
+		assert.Equal(t, "info", fields["level"])
 	})
 }
 
@@ -77,8 +128,17 @@ func TestWarn(t *testing.T) {
 	LogAndAssertJSON(t, func(log *Logger) {
 		log.Warn("test")
 	}, func(fields Fields) {
-		assert.Equal(t, fields["msg"], "test")
+		assert.Equal(t, "test", fields["msg"])
-		assert.Equal(t, fields["level"], "warning")
+		assert.Equal(t, "warning", fields["level"])
+	})
+}
+
+func TestLog(t *testing.T) {
+	LogAndAssertJSON(t, func(log *Logger) {
+		log.Log(WarnLevel, "test")
+	}, func(fields Fields) {
+		assert.Equal(t, "test", fields["msg"])
+		assert.Equal(t, "warning", fields["level"])
 	})
 }
 
@@ -86,7 +146,7 @@ func TestInfolnShouldAddSpacesBetweenStrings(t *testing.T) {
 	LogAndAssertJSON(t, func(log *Logger) {
 		log.Infoln("test", "test")
 	}, func(fields Fields) {
-		assert.Equal(t, fields["msg"], "test test")
+		assert.Equal(t, "test test", fields["msg"])
 	})
 }
 
@@ -94,7 +154,7 @@ func TestInfolnShouldAddSpacesBetweenStringAndNonstring(t *testing.T) {
 	LogAndAssertJSON(t, func(log *Logger) {
 		log.Infoln("test", 10)
 	}, func(fields Fields) {
-		assert.Equal(t, fields["msg"], "test 10")
+		assert.Equal(t, "test 10", fields["msg"])
 	})
 }
 
@@ -102,7 +162,7 @@ func TestInfolnShouldAddSpacesBetweenTwoNonStrings(t *testing.T) {
 	LogAndAssertJSON(t, func(log *Logger) {
 		log.Infoln(10, 10)
 	}, func(fields Fields) {
-		assert.Equal(t, fields["msg"], "10 10")
+		assert.Equal(t, "10 10", fields["msg"])
 	})
 }
 
@@ -110,7 +170,7 @@ func TestInfoShouldAddSpacesBetweenTwoNonStrings(t *testing.T) {
 	LogAndAssertJSON(t, func(log *Logger) {
 		log.Infoln(10, 10)
 	}, func(fields Fields) {
-		assert.Equal(t, fields["msg"], "10 10")
+		assert.Equal(t, "10 10", fields["msg"])
 	})
 }
 
@@ -118,7 +178,7 @@ func TestInfoShouldNotAddSpacesBetweenStringAndNonstring(t *testing.T) {
 	LogAndAssertJSON(t, func(log *Logger) {
 		log.Info("test", 10)
 	}, func(fields Fields) {
-		assert.Equal(t, fields["msg"], "test10")
+		assert.Equal(t, "test10", fields["msg"])
 	})
 }
 
@@ -126,7 +186,7 @@ func TestInfoShouldNotAddSpacesBetweenStrings(t *testing.T) {
 	LogAndAssertJSON(t, func(log *Logger) {
 		log.Info("test", "test")
 	}, func(fields Fields) {
-		assert.Equal(t, fields["msg"], "testtest")
+		assert.Equal(t, "testtest", fields["msg"])
 	})
 }
 
@@ -164,7 +224,7 @@ func TestUserSuppliedFieldDoesNotOverwriteDefaults(t *testing.T) {
 	LogAndAssertJSON(t, func(log *Logger) {
 		log.WithField("msg", "hello").Info("test")
 	}, func(fields Fields) {
-		assert.Equal(t, fields["msg"], "test")
+		assert.Equal(t, "test", fields["msg"])
 	})
 }
 
@@ -172,8 +232,8 @@ func TestUserSuppliedMsgFieldHasPrefix(t *testing.T) {
 	LogAndAssertJSON(t, func(log *Logger) {
 		log.WithField("msg", "hello").Info("test")
 	}, func(fields Fields) {
-		assert.Equal(t, fields["msg"], "test")
+		assert.Equal(t, "test", fields["msg"])
-		assert.Equal(t, fields["fields.msg"], "hello")
+		assert.Equal(t, "hello", fields["fields.msg"])
 	})
 }
 
@@ -181,7 +241,7 @@ func TestUserSuppliedTimeFieldHasPrefix(t *testing.T) {
 	LogAndAssertJSON(t, func(log *Logger) {
 		log.WithField("time", "hello").Info("test")
 	}, func(fields Fields) {
-		assert.Equal(t, fields["fields.time"], "hello")
+		assert.Equal(t, "hello", fields["fields.time"])
 	})
 }
 
@@ -189,8 +249,8 @@ func TestUserSuppliedLevelFieldHasPrefix(t *testing.T) {
 	LogAndAssertJSON(t, func(log *Logger) {
 		log.WithField("level", 1).Info("test")
 	}, func(fields Fields) {
-		assert.Equal(t, fields["level"], "info")
+		assert.Equal(t, "info", fields["level"])
-		assert.Equal(t, fields["fields.level"], 1)
+		assert.Equal(t, 1.0, fields["fields.level"]) // JSON has floats only
 	})
 }
 
@@ -208,8 +268,66 @@ func TestDefaultFieldsAreNotPrefixed(t *testing.T) {
 	})
 }
 
-func TestDoubleLoggingDoesntPrefixPreviousFields(t *testing.T) {
+func TestWithTimeShouldOverrideTime(t *testing.T) {
+	now := time.Now().Add(24 * time.Hour)
 
+	LogAndAssertJSON(t, func(log *Logger) {
+		log.WithTime(now).Info("foobar")
+	}, func(fields Fields) {
+		assert.Equal(t, fields["time"], now.Format(time.RFC3339))
+	})
+}
+
+func TestWithTimeShouldNotOverrideFields(t *testing.T) {
+	now := time.Now().Add(24 * time.Hour)
+
+	LogAndAssertJSON(t, func(log *Logger) {
+		log.WithField("herp", "derp").WithTime(now).Info("blah")
+	}, func(fields Fields) {
+		assert.Equal(t, fields["time"], now.Format(time.RFC3339))
+		assert.Equal(t, fields["herp"], "derp")
+	})
+}
+
+func TestWithFieldShouldNotOverrideTime(t *testing.T) {
+	now := time.Now().Add(24 * time.Hour)
+
+	LogAndAssertJSON(t, func(log *Logger) {
+		log.WithTime(now).WithField("herp", "derp").Info("blah")
+	}, func(fields Fields) {
+		assert.Equal(t, fields["time"], now.Format(time.RFC3339))
+		assert.Equal(t, fields["herp"], "derp")
+	})
+}
+
+func TestTimeOverrideMultipleLogs(t *testing.T) {
+	var buffer bytes.Buffer
+	var firstFields, secondFields Fields
+
+	logger := New()
+	logger.Out = &buffer
+	formatter := new(JSONFormatter)
+	formatter.TimestampFormat = time.StampMilli
+	logger.Formatter = formatter
+
+	llog := logger.WithField("herp", "derp")
+	llog.Info("foo")
+
+	err := json.Unmarshal(buffer.Bytes(), &firstFields)
+	assert.NoError(t, err, "should have decoded first message")
+
+	buffer.Reset()
+
+	time.Sleep(10 * time.Millisecond)
+	llog.Info("bar")
+
+	err = json.Unmarshal(buffer.Bytes(), &secondFields)
+	assert.NoError(t, err, "should have decoded second message")
+
+	assert.NotEqual(t, firstFields["time"], secondFields["time"], "timestamps should not be equal")
+}
+
+func TestDoubleLoggingDoesntPrefixPreviousFields(t *testing.T) {
 	var buffer bytes.Buffer
 	var fields Fields
 
@@ -223,7 +341,7 @@ func TestDoubleLoggingDoesntPrefixPreviousFields(t *testing.T) {
 
 	err := json.Unmarshal(buffer.Bytes(), &fields)
 	assert.NoError(t, err, "should have decoded first message")
-	assert.Len(t, fields, 4, "should only have msg/time/level/context fields")
+	assert.Equal(t, len(fields), 4, "should only have msg/time/level/context fields")
 	assert.Equal(t, fields["msg"], "looks delicious")
 	assert.Equal(t, fields["context"], "eating raw fish")
 
@@ -233,14 +351,119 @@ func TestDoubleLoggingDoesntPrefixPreviousFields(t *testing.T) {
 
 	err = json.Unmarshal(buffer.Bytes(), &fields)
 	assert.NoError(t, err, "should have decoded second message")
-	assert.Len(t, fields, 4, "should only have msg/time/level/context fields")
+	assert.Equal(t, len(fields), 4, "should only have msg/time/level/context fields")
-	assert.Equal(t, fields["msg"], "omg it is!")
+	assert.Equal(t, "omg it is!", fields["msg"])
-	assert.Equal(t, fields["context"], "eating raw fish")
+	assert.Equal(t, "eating raw fish", fields["context"])
 	assert.Nil(t, fields["fields.msg"], "should not have prefixed previous `msg` entry")
+}
 
+func TestNestedLoggingReportsCorrectCaller(t *testing.T) {
+	var buffer bytes.Buffer
+	var fields Fields
+
+	logger := New()
+	logger.Out = &buffer
+	logger.Formatter = new(JSONFormatter)
+	logger.ReportCaller = true
+
+	llog := logger.WithField("context", "eating raw fish")
+
+	llog.Info("looks delicious")
+	_, _, line, _ := runtime.Caller(0)
+
+	err := json.Unmarshal(buffer.Bytes(), &fields)
+	require.NoError(t, err, "should have decoded first message")
+	assert.Equal(t, 6, len(fields), "should have msg/time/level/func/context fields")
+	assert.Equal(t, "looks delicious", fields["msg"])
+	assert.Equal(t, "eating raw fish", fields["context"])
+	assert.Equal(t,
+		"git.internal/re/logrus_test.TestNestedLoggingReportsCorrectCaller", fields["func"])
+	cwd, err := os.Getwd()
+	require.NoError(t, err)
+	assert.Equal(t, filepath.ToSlash(fmt.Sprintf("%s/logrus_test.go:%d", cwd, line-1)), filepath.ToSlash(fields["file"].(string)))
+
+	buffer.Reset()
+
+	logger.WithFields(Fields{
+		"Clyde": "Stubblefield",
+	}).WithFields(Fields{
+		"Jab'o": "Starks",
+	}).WithFields(Fields{
+		"uri": "https://www.youtube.com/watch?v=V5DTznu-9v0",
+	}).WithFields(Fields{
+		"func": "y drummer",
+	}).WithFields(Fields{
+		"James": "Brown",
+	}).Print("The hardest workin' man in show business")
+	_, _, line, _ = runtime.Caller(0)
+
+	err = json.Unmarshal(buffer.Bytes(), &fields)
+	assert.NoError(t, err, "should have decoded second message")
+	assert.Equal(t, 11, len(fields), "should have all builtin fields plus foo,bar,baz,...")
+	assert.Equal(t, "Stubblefield", fields["Clyde"])
+	assert.Equal(t, "Starks", fields["Jab'o"])
+	assert.Equal(t, "https://www.youtube.com/watch?v=V5DTznu-9v0", fields["uri"])
+	assert.Equal(t, "y drummer", fields["fields.func"])
+	assert.Equal(t, "Brown", fields["James"])
+	assert.Equal(t, "The hardest workin' man in show business", fields["msg"])
+	assert.Nil(t, fields["fields.msg"], "should not have prefixed previous `msg` entry")
+	assert.Equal(t,
+		"git.internal/re/logrus_test.TestNestedLoggingReportsCorrectCaller", fields["func"])
+	require.NoError(t, err)
+	assert.Equal(t, filepath.ToSlash(fmt.Sprintf("%s/logrus_test.go:%d", cwd, line-1)), filepath.ToSlash(fields["file"].(string)))
+
+	logger.ReportCaller = false // return to default value
+}
+
+func logLoop(iterations int, reportCaller bool) {
+	var buffer bytes.Buffer
+
+	logger := New()
+	logger.Out = &buffer
+	logger.Formatter = new(JSONFormatter)
+	logger.ReportCaller = reportCaller
+
+	for i := 0; i < iterations; i++ {
+		logger.Infof("round %d of %d", i, iterations)
+	}
+}
+
+// Assertions for upper bounds to reporting overhead
+func TestCallerReportingOverhead(t *testing.T) {
+	iterations := 5000
+	before := time.Now()
+	logLoop(iterations, false)
+	during := time.Now()
+	logLoop(iterations, true)
+	after := time.Now()
+
+	elapsedNotReporting := during.Sub(before).Nanoseconds()
+	elapsedReporting := after.Sub(during).Nanoseconds()
+
+	maxDelta := 1 * time.Second
+	assert.WithinDuration(t, during, before, maxDelta,
+		"%d log calls without caller name lookup takes less than %d second(s) (was %d nanoseconds)",
+		iterations, maxDelta.Seconds(), elapsedNotReporting)
+	assert.WithinDuration(t, after, during, maxDelta,
+		"%d log calls without caller name lookup takes less than %d second(s) (was %d nanoseconds)",
+		iterations, maxDelta.Seconds(), elapsedReporting)
+}
+
+// benchmarks for both with and without caller-function reporting
+func BenchmarkWithoutCallerTracing(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		logLoop(1000, false)
+	}
+}
+
+func BenchmarkWithCallerTracing(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		logLoop(1000, true)
+	}
 }
 
 func TestConvertLevelToString(t *testing.T) {
+	assert.Equal(t, "trace", TraceLevel.String())
 	assert.Equal(t, "debug", DebugLevel.String())
 	assert.Equal(t, "info", InfoLevel.String())
 	assert.Equal(t, "warning", WarnLevel.String())
@@ -254,30 +477,320 @@ func TestParseLevel(t *testing.T) {
 	assert.Nil(t, err)
 	assert.Equal(t, PanicLevel, l)
 
+	l, err = ParseLevel("PANIC")
+	assert.Nil(t, err)
+	assert.Equal(t, PanicLevel, l)
+
 	l, err = ParseLevel("fatal")
 	assert.Nil(t, err)
 	assert.Equal(t, FatalLevel, l)
 
+	l, err = ParseLevel("FATAL")
+	assert.Nil(t, err)
+	assert.Equal(t, FatalLevel, l)
+
 	l, err = ParseLevel("error")
 	assert.Nil(t, err)
 	assert.Equal(t, ErrorLevel, l)
 
+	l, err = ParseLevel("ERROR")
+	assert.Nil(t, err)
+	assert.Equal(t, ErrorLevel, l)
+
 	l, err = ParseLevel("warn")
 	assert.Nil(t, err)
 	assert.Equal(t, WarnLevel, l)
 
+	l, err = ParseLevel("WARN")
+	assert.Nil(t, err)
+	assert.Equal(t, WarnLevel, l)
+
 	l, err = ParseLevel("warning")
 	assert.Nil(t, err)
 	assert.Equal(t, WarnLevel, l)
 
+	l, err = ParseLevel("WARNING")
+	assert.Nil(t, err)
+	assert.Equal(t, WarnLevel, l)
+
 	l, err = ParseLevel("info")
 	assert.Nil(t, err)
 	assert.Equal(t, InfoLevel, l)
 
+	l, err = ParseLevel("INFO")
+	assert.Nil(t, err)
+	assert.Equal(t, InfoLevel, l)
+
 	l, err = ParseLevel("debug")
 	assert.Nil(t, err)
 	assert.Equal(t, DebugLevel, l)
 
-	l, err = ParseLevel("invalid")
+	l, err = ParseLevel("DEBUG")
+	assert.Nil(t, err)
+	assert.Equal(t, DebugLevel, l)
+
+	l, err = ParseLevel("trace")
+	assert.Nil(t, err)
+	assert.Equal(t, TraceLevel, l)
+
+	l, err = ParseLevel("TRACE")
+	assert.Nil(t, err)
+	assert.Equal(t, TraceLevel, l)
+
+	_, err = ParseLevel("invalid")
 	assert.Equal(t, "not a valid logrus Level: \"invalid\"", err.Error())
 }
+
+func TestLevelString(t *testing.T) {
+	var loggerlevel Level
+	loggerlevel = 32000
+
+	_ = loggerlevel.String()
+}
+
+func TestGetSetLevelRace(t *testing.T) {
+	wg := sync.WaitGroup{}
+	for i := 0; i < 100; i++ {
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+			if i%2 == 0 {
+				SetLevel(InfoLevel)
+			} else {
+				GetLevel()
+			}
+		}(i)
+
+	}
+	wg.Wait()
+}
+
+func TestLoggingRace(t *testing.T) {
+	logger := New()
+
+	var wg sync.WaitGroup
+	wg.Add(100)
+
+	for i := 0; i < 100; i++ {
+		go func() {
+			logger.Info("info")
+			wg.Done()
+		}()
+	}
+	wg.Wait()
+}
+
+func TestLoggingRaceWithHooksOnEntry(t *testing.T) {
+	logger := New()
+	hook := new(ModifyHook)
+	logger.AddHook(hook)
+	entry := logger.WithField("context", "clue")
+
+	var (
+		wg    sync.WaitGroup
+		mtx   sync.Mutex
+		start bool
+	)
+
+	cond := sync.NewCond(&mtx)
+
+	wg.Add(100)
+
+	for i := 0; i < 50; i++ {
+		go func() {
+			cond.L.Lock()
+			for !start {
+				cond.Wait()
+			}
+			cond.L.Unlock()
+			for j := 0; j < 100; j++ {
+				entry.Info("info")
+			}
+			wg.Done()
+		}()
+	}
+
+	for i := 0; i < 50; i++ {
+		go func() {
+			cond.L.Lock()
+			for !start {
+				cond.Wait()
+			}
+			cond.L.Unlock()
+			for j := 0; j < 100; j++ {
+				entry.WithField("another field", "with some data").Info("info")
+			}
+			wg.Done()
+		}()
+	}
+
+	cond.L.Lock()
+	start = true
+	cond.L.Unlock()
+	cond.Broadcast()
+	wg.Wait()
+}
+
+func TestReplaceHooks(t *testing.T) {
+	old, cur := &TestHook{}, &TestHook{}
+
+	logger := New()
+	logger.SetOutput(ioutil.Discard)
+	logger.AddHook(old)
+
+	hooks := make(LevelHooks)
+	hooks.Add(cur)
+	replaced := logger.ReplaceHooks(hooks)
+
+	logger.Info("test")
+
+	assert.Equal(t, old.Fired, false)
+	assert.Equal(t, cur.Fired, true)
+
+	logger.ReplaceHooks(replaced)
+	logger.Info("test")
+	assert.Equal(t, old.Fired, true)
+}
+
+// Compile test
+func TestLogrusInterfaces(t *testing.T) {
+	var buffer bytes.Buffer
+	// This verifies FieldLogger and Ext1FieldLogger work as designed.
+	// Please don't use them. Use Logger and Entry directly.
+	fn := func(xl Ext1FieldLogger) {
+		var l FieldLogger = xl
+		b := l.WithField("key", "value")
+		b.Debug("Test")
+	}
+	// test logger
+	logger := New()
+	logger.Out = &buffer
+	fn(logger)
+
+	// test Entry
+	e := logger.WithField("another", "value")
+	fn(e)
+}
+
+// Implements io.Writer using channels for synchronization, so we can wait on
+// the Entry.Writer goroutine to write in a non-racey way. This does assume that
+// there is a single call to Logger.Out for each message.
+type channelWriter chan []byte
+
+func (cw channelWriter) Write(p []byte) (int, error) {
+	cw <- p
+	return len(p), nil
+}
+
+func TestEntryWriter(t *testing.T) {
+	cw := channelWriter(make(chan []byte, 1))
+	log := New()
+	log.Out = cw
+	log.Formatter = new(JSONFormatter)
+	_, err := log.WithField("foo", "bar").WriterLevel(WarnLevel).Write([]byte("hello\n"))
+	if err != nil {
+		t.Error("unexecpted error", err)
+	}
+
+	bs := <-cw
+	var fields Fields
+	err = json.Unmarshal(bs, &fields)
+	assert.Nil(t, err)
+	assert.Equal(t, fields["foo"], "bar")
+	assert.Equal(t, fields["level"], "warning")
+}
+
+func TestLogLevelEnabled(t *testing.T) {
+	log := New()
+	log.SetLevel(PanicLevel)
+	assert.Equal(t, true, log.IsLevelEnabled(PanicLevel))
+	assert.Equal(t, false, log.IsLevelEnabled(FatalLevel))
+	assert.Equal(t, false, log.IsLevelEnabled(ErrorLevel))
+	assert.Equal(t, false, log.IsLevelEnabled(WarnLevel))
+	assert.Equal(t, false, log.IsLevelEnabled(InfoLevel))
+	assert.Equal(t, false, log.IsLevelEnabled(DebugLevel))
+	assert.Equal(t, false, log.IsLevelEnabled(TraceLevel))
+
+	log.SetLevel(FatalLevel)
+	assert.Equal(t, true, log.IsLevelEnabled(PanicLevel))
+	assert.Equal(t, true, log.IsLevelEnabled(FatalLevel))
+	assert.Equal(t, false, log.IsLevelEnabled(ErrorLevel))
+	assert.Equal(t, false, log.IsLevelEnabled(WarnLevel))
+	assert.Equal(t, false, log.IsLevelEnabled(InfoLevel))
+	assert.Equal(t, false, log.IsLevelEnabled(DebugLevel))
+	assert.Equal(t, false, log.IsLevelEnabled(TraceLevel))
+
+	log.SetLevel(ErrorLevel)
+	assert.Equal(t, true, log.IsLevelEnabled(PanicLevel))
+	assert.Equal(t, true, log.IsLevelEnabled(FatalLevel))
+	assert.Equal(t, true, log.IsLevelEnabled(ErrorLevel))
+	assert.Equal(t, false, log.IsLevelEnabled(WarnLevel))
+	assert.Equal(t, false, log.IsLevelEnabled(InfoLevel))
+	assert.Equal(t, false, log.IsLevelEnabled(DebugLevel))
+	assert.Equal(t, false, log.IsLevelEnabled(TraceLevel))
+
+	log.SetLevel(WarnLevel)
+	assert.Equal(t, true, log.IsLevelEnabled(PanicLevel))
+	assert.Equal(t, true, log.IsLevelEnabled(FatalLevel))
+	assert.Equal(t, true, log.IsLevelEnabled(ErrorLevel))
+	assert.Equal(t, true, log.IsLevelEnabled(WarnLevel))
+	assert.Equal(t, false, log.IsLevelEnabled(InfoLevel))
+	assert.Equal(t, false, log.IsLevelEnabled(DebugLevel))
+	assert.Equal(t, false, log.IsLevelEnabled(TraceLevel))
+
+	log.SetLevel(InfoLevel)
+	assert.Equal(t, true, log.IsLevelEnabled(PanicLevel))
+	assert.Equal(t, true, log.IsLevelEnabled(FatalLevel))
+	assert.Equal(t, true, log.IsLevelEnabled(ErrorLevel))
+	assert.Equal(t, true, log.IsLevelEnabled(WarnLevel))
+	assert.Equal(t, true, log.IsLevelEnabled(InfoLevel))
+	assert.Equal(t, false, log.IsLevelEnabled(DebugLevel))
+	assert.Equal(t, false, log.IsLevelEnabled(TraceLevel))
+
+	log.SetLevel(DebugLevel)
+	assert.Equal(t, true, log.IsLevelEnabled(PanicLevel))
+	assert.Equal(t, true, log.IsLevelEnabled(FatalLevel))
+	assert.Equal(t, true, log.IsLevelEnabled(ErrorLevel))
+	assert.Equal(t, true, log.IsLevelEnabled(WarnLevel))
+	assert.Equal(t, true, log.IsLevelEnabled(InfoLevel))
+	assert.Equal(t, true, log.IsLevelEnabled(DebugLevel))
+	assert.Equal(t, false, log.IsLevelEnabled(TraceLevel))
+
+	log.SetLevel(TraceLevel)
+	assert.Equal(t, true, log.IsLevelEnabled(PanicLevel))
+	assert.Equal(t, true, log.IsLevelEnabled(FatalLevel))
+	assert.Equal(t, true, log.IsLevelEnabled(ErrorLevel))
+	assert.Equal(t, true, log.IsLevelEnabled(WarnLevel))
+	assert.Equal(t, true, log.IsLevelEnabled(InfoLevel))
+	assert.Equal(t, true, log.IsLevelEnabled(DebugLevel))
+	assert.Equal(t, true, log.IsLevelEnabled(TraceLevel))
+}
+
+func TestReportCallerOnTextFormatter(t *testing.T) {
+	l := New()
+
+	l.Formatter.(*TextFormatter).ForceColors = true
+	l.Formatter.(*TextFormatter).DisableColors = false
+	l.WithFields(Fields{"func": "func", "file": "file"}).Info("test")
+
+	l.Formatter.(*TextFormatter).ForceColors = false
+	l.Formatter.(*TextFormatter).DisableColors = true
+	l.WithFields(Fields{"func": "func", "file": "file"}).Info("test")
+}
+
+func TestSetReportCallerRace(t *testing.T) {
+	l := New()
+	l.Out = ioutil.Discard
+	l.SetReportCaller(true)
+
+	var wg sync.WaitGroup
+	wg.Add(100)
+
+	for i := 0; i < 100; i++ {
+		go func() {
+			l.Error("Some Error")
+			wg.Done()
+		}()
+	}
+	wg.Wait()
+}

terminal_check_appengine.go

@@ -0,0 +1,11 @@
+// +build appengine
+
+package logrus
+
+import (
+	"io"
+)
+
+func checkIfTerminal(w io.Writer) bool {
+	return true
+}

terminal_check_bsd.go

@@ -0,0 +1,13 @@
+// +build darwin dragonfly freebsd netbsd openbsd
+// +build !js
+
+package logrus
+
+import "golang.org/x/sys/unix"
+
+const ioctlReadTermios = unix.TIOCGETA
+
+func isTerminal(fd int) bool {
+	_, err := unix.IoctlGetTermios(fd, ioctlReadTermios)
+	return err == nil
+}

terminal_check_js.go

@@ -0,0 +1,7 @@
+// +build js
+
+package logrus
+
+func isTerminal(fd int) bool {
+	return false
+}

terminal_check_no_terminal.go

@@ -0,0 +1,11 @@
+// +build js nacl plan9
+
+package logrus
+
+import (
+	"io"
+)
+
+func checkIfTerminal(w io.Writer) bool {
+	return false
+}

terminal_check_notappengine.go

@@ -0,0 +1,17 @@
+// +build !appengine,!js,!windows,!nacl,!plan9
+
+package logrus
+
+import (
+	"io"
+	"os"
+)
+
+func checkIfTerminal(w io.Writer) bool {
+	switch v := w.(type) {
+	case *os.File:
+		return isTerminal(int(v.Fd()))
+	default:
+		return false
+	}
+}

terminal_check_solaris.go

@@ -0,0 +1,11 @@
+package logrus
+
+import (
+	"golang.org/x/sys/unix"
+)
+
+// IsTerminal returns true if the given file descriptor is a terminal.
+func isTerminal(fd int) bool {
+	_, err := unix.IoctlGetTermio(fd, unix.TCGETA)
+	return err == nil
+}

terminal_check_unix.go

@@ -0,0 +1,13 @@
+// +build linux aix zos
+// +build !js
+
+package logrus
+
+import "golang.org/x/sys/unix"
+
+const ioctlReadTermios = unix.TCGETS
+
+func isTerminal(fd int) bool {
+	_, err := unix.IoctlGetTermios(fd, ioctlReadTermios)
+	return err == nil
+}

terminal_check_windows.go

@@ -0,0 +1,27 @@
+// +build !appengine,!js,windows
+
+package logrus
+
+import (
+	"io"
+	"os"
+
+	"golang.org/x/sys/windows"
+)
+
+func checkIfTerminal(w io.Writer) bool {
+	switch v := w.(type) {
+	case *os.File:
+		handle := windows.Handle(v.Fd())
+		var mode uint32
+		if err := windows.GetConsoleMode(handle, &mode); err != nil {
+			return false
+		}
+		mode |= windows.ENABLE_VIRTUAL_TERMINAL_PROCESSING
+		if err := windows.SetConsoleMode(handle, mode); err != nil {
+			return false
+		}
+		return true
+	}
+	return false
+}

terminal_darwin.go

@@ -1,12 +0,0 @@
-// Based on ssh/terminal:
-// Copyright 2013 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package logrus
-
-import "syscall"
-
-const ioctlReadTermios = syscall.TIOCGETA
-
-type Termios syscall.Termios

terminal_freebsd.go

@@ -1,20 +0,0 @@
-/*
-  Go 1.2 doesn't include Termios for FreeBSD. This should be added in 1.3 and this could be merged with terminal_darwin.
-*/
-package logrus
-
-import (
-	"syscall"
-)
-
-const ioctlReadTermios = syscall.TIOCGETA
-
-type Termios struct {
-	Iflag  uint32
-	Oflag  uint32
-	Cflag  uint32
-	Lflag  uint32
-	Cc     [20]uint8
-	Ispeed uint32
-	Ospeed uint32
-}

terminal_linux.go

@@ -1,12 +0,0 @@
-// Based on ssh/terminal:
-// Copyright 2013 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package logrus
-
-import "syscall"
-
-const ioctlReadTermios = syscall.TCGETS
-
-type Termios syscall.Termios

terminal_notwindows.go

@@ -1,21 +0,0 @@
-// Based on ssh/terminal:
-// Copyright 2011 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build linux,!appengine darwin freebsd
-
-package logrus
-
-import (
-	"syscall"
-	"unsafe"
-)
-
-// IsTerminal returns true if the given file descriptor is a terminal.
-func IsTerminal() bool {
-	fd := syscall.Stdout
-	var termios Termios
-	_, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlReadTermios, uintptr(unsafe.Pointer(&termios)), 0, 0, 0)
-	return err == 0
-}

terminal_windows.go

@@ -1,27 +0,0 @@
-// Based on ssh/terminal:
-// Copyright 2011 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build windows
-
-package logrus
-
-import (
-	"syscall"
-	"unsafe"
-)
-
-var kernel32 = syscall.NewLazyDLL("kernel32.dll")
-
-var (
-	procGetConsoleMode = kernel32.NewProc("GetConsoleMode")
-)
-
-// IsTerminal returns true if the given file descriptor is a terminal.
-func IsTerminal() bool {
-	fd := syscall.Stdout
-	var st uint32
-	r, _, e := syscall.Syscall(procGetConsoleMode.Addr(), 2, uintptr(fd), uintptr(unsafe.Pointer(&st)), 0)
-	return r != 0 && e == 0
-}

text_formatter.go

@@ -3,68 +3,225 @@ package logrus
 import (
 	"bytes"
 	"fmt"
-	"regexp"
+	"os"
+	"runtime"
 	"sort"
+	"strconv"
 	"strings"
+	"sync"
 	"time"
+	"unicode/utf8"
 )
 
 const (
-	nocolor = 0
+	red    = 31
-	red     = 31
+	yellow = 33
-	green   = 32
+	blue   = 36
-	yellow  = 33
+	gray   = 37
-	blue    = 34
 )
 
-var (
+var baseTimestamp time.Time
-	baseTimestamp time.Time
-	isTerminal    bool
-	noQuoteNeeded *regexp.Regexp
-)
 
 func init() {
 	baseTimestamp = time.Now()
-	isTerminal = IsTerminal()
-}
-
-func miniTS() int {
-	return int(time.Since(baseTimestamp) / time.Second)
 }
 
+// TextFormatter formats logs into text
 type TextFormatter struct {
 	// Set to true to bypass checking for a TTY before outputting colors.
-	ForceColors   bool
+	ForceColors bool
+
+	// Force disabling colors.
 	DisableColors bool
-	// Set to true to disable timestamp logging (useful when the output
+
-	// is redirected to a logging system already adding a timestamp)
+	// Force quoting of all values
+	ForceQuote bool
+
+	// DisableQuote disables quoting for all values.
+	// DisableQuote will have a lower priority than ForceQuote.
+	// If both of them are set to true, quote will be forced on all values.
+	DisableQuote bool
+
+	// Override coloring based on CLICOLOR and CLICOLOR_FORCE. - https://bixense.com/clicolors/
+	EnvironmentOverrideColors bool
+
+	// Disable timestamp logging. useful when output is redirected to logging
+	// system that already adds timestamps.
 	DisableTimestamp bool
+
+	// Enable logging the full timestamp when a TTY is attached instead of just
+	// the time passed since beginning of execution.
+	FullTimestamp bool
+
+	// TimestampFormat to use for display when a full timestamp is printed.
+	// The format to use is the same than for time.Format or time.Parse from the standard
+	// library.
+	// The standard Library already provides a set of predefined format.
+	TimestampFormat string
+
+	// The fields are sorted by default for a consistent output. For applications
+	// that log extremely frequently and don't use the JSON formatter this may not
+	// be desired.
+	DisableSorting bool
+
+	// The keys sorting function, when uninitialized it uses sort.Strings.
+	SortingFunc func([]string)
+
+	// Disables the truncation of the level text to 4 characters.
+	DisableLevelTruncation bool
+
+	// PadLevelText Adds padding the level text so that all the levels output at the same length
+	// PadLevelText is a superset of the DisableLevelTruncation option
+	PadLevelText bool
+
+	// QuoteEmptyFields will wrap empty fields in quotes if true
+	QuoteEmptyFields bool
+
+	// Whether the logger's out is to a terminal
+	isTerminal bool
+
+	// FieldMap allows users to customize the names of keys for default fields.
+	// As an example:
+	// formatter := &TextFormatter{
+	//     FieldMap: FieldMap{
+	//         FieldKeyTime:  "@timestamp",
+	//         FieldKeyLevel: "@level",
+	//         FieldKeyMsg:   "@message"}}
+	FieldMap FieldMap
+
+	// CallerPrettyfier can be set by the user to modify the content
+	// of the function and file keys in the data when ReportCaller is
+	// activated. If any of the returned value is the empty string the
+	// corresponding key will be removed from fields.
+	CallerPrettyfier func(*runtime.Frame) (function string, file string)
+
+	terminalInitOnce sync.Once
+
+	// The max length of the level text, generated dynamically on init
+	levelTextMaxLength int
 }
 
-func (f *TextFormatter) Format(entry *Entry) ([]byte, error) {
+func (f *TextFormatter) init(entry *Entry) {
+	if entry.Logger != nil {
+		f.isTerminal = checkIfTerminal(entry.Logger.Out)
+	}
+	// Get the max length of the level text
+	for _, level := range AllLevels {
+		levelTextLength := utf8.RuneCount([]byte(level.String()))
+		if levelTextLength > f.levelTextMaxLength {
+			f.levelTextMaxLength = levelTextLength
+		}
+	}
+}
 
-	var keys []string
+func (f *TextFormatter) isColored() bool {
-	for k := range entry.Data {
+	isColored := f.ForceColors || (f.isTerminal && (runtime.GOOS != "windows"))
+
+	if f.EnvironmentOverrideColors {
+		switch force, ok := os.LookupEnv("CLICOLOR_FORCE"); {
+		case ok && force != "0":
+			isColored = true
+		case ok && force == "0", os.Getenv("CLICOLOR") == "0":
+			isColored = false
+		}
+	}
+
+	return isColored && !f.DisableColors
+}
+
+// Format renders a single log entry
+func (f *TextFormatter) Format(entry *Entry) ([]byte, error) {
+	data := make(Fields)
+	for k, v := range entry.Data {
+		data[k] = v
+	}
+	prefixFieldClashes(data, f.FieldMap, entry.HasCaller())
+	keys := make([]string, 0, len(data))
+	for k := range data {
 		keys = append(keys, k)
 	}
-	sort.Strings(keys)
 
-	b := &bytes.Buffer{}
+	var funcVal, fileVal string
 
-	prefixFieldClashes(entry.Data)
+	fixedKeys := make([]string, 0, 4+len(data))
-
+	if !f.DisableTimestamp {
-	isColored := (f.ForceColors || isTerminal) && !f.DisableColors
+		fixedKeys = append(fixedKeys, f.FieldMap.resolve(FieldKeyTime))
-
+	}
-	if isColored {
+	fixedKeys = append(fixedKeys, f.FieldMap.resolve(FieldKeyLevel))
-		printColored(b, entry, keys)
+	if entry.Message != "" {
-	} else {
+		fixedKeys = append(fixedKeys, f.FieldMap.resolve(FieldKeyMsg))
-		if !f.DisableTimestamp {
+	}
-			f.appendKeyValue(b, "time", entry.Time.Format(time.RFC3339))
+	if entry.err != "" {
+		fixedKeys = append(fixedKeys, f.FieldMap.resolve(FieldKeyLogrusError))
+	}
+	if entry.HasCaller() {
+		if f.CallerPrettyfier != nil {
+			funcVal, fileVal = f.CallerPrettyfier(entry.Caller)
+		} else {
+			funcVal = entry.Caller.Function
+			fileVal = fmt.Sprintf("%s:%d", entry.Caller.File, entry.Caller.Line)
 		}
-		f.appendKeyValue(b, "level", entry.Level.String())
+
-		f.appendKeyValue(b, "msg", entry.Message)
+		if funcVal != "" {
-		for _, key := range keys {
+			fixedKeys = append(fixedKeys, f.FieldMap.resolve(FieldKeyFunc))
-			f.appendKeyValue(b, key, entry.Data[key])
+		}
+		if fileVal != "" {
+			fixedKeys = append(fixedKeys, f.FieldMap.resolve(FieldKeyFile))
+		}
+	}
+
+	if !f.DisableSorting {
+		if f.SortingFunc == nil {
+			sort.Strings(keys)
+			fixedKeys = append(fixedKeys, keys...)
+		} else {
+			if !f.isColored() {
+				fixedKeys = append(fixedKeys, keys...)
+				f.SortingFunc(fixedKeys)
+			} else {
+				f.SortingFunc(keys)
+			}
+		}
+	} else {
+		fixedKeys = append(fixedKeys, keys...)
+	}
+
+	var b *bytes.Buffer
+	if entry.Buffer != nil {
+		b = entry.Buffer
+	} else {
+		b = &bytes.Buffer{}
+	}
+
+	f.terminalInitOnce.Do(func() { f.init(entry) })
+
+	timestampFormat := f.TimestampFormat
+	if timestampFormat == "" {
+		timestampFormat = defaultTimestampFormat
+	}
+	if f.isColored() {
+		f.printColored(b, entry, keys, data, timestampFormat)
+	} else {
+
+		for _, key := range fixedKeys {
+			var value interface{}
+			switch {
+			case key == f.FieldMap.resolve(FieldKeyTime):
+				value = entry.Time.Format(timestampFormat)
+			case key == f.FieldMap.resolve(FieldKeyLevel):
+				value = entry.Level.String()
+			case key == f.FieldMap.resolve(FieldKeyMsg):
+				value = entry.Message
+			case key == f.FieldMap.resolve(FieldKeyLogrusError):
+				value = entry.err
+			case key == f.FieldMap.resolve(FieldKeyFunc) && entry.HasCaller():
+				value = funcVal
+			case key == f.FieldMap.resolve(FieldKeyFile) && entry.HasCaller():
+				value = fileVal
+			default:
+				value = data[key]
+			}
+			f.appendKeyValue(b, key, value)
 		}
 	}
 
@@ -72,53 +229,111 @@ func (f *TextFormatter) Format(entry *Entry) ([]byte, error) {
 	return b.Bytes(), nil
 }
 
-func printColored(b *bytes.Buffer, entry *Entry, keys []string) {
+func (f *TextFormatter) printColored(b *bytes.Buffer, entry *Entry, keys []string, data Fields, timestampFormat string) {
 	var levelColor int
 	switch entry.Level {
+	case DebugLevel, TraceLevel:
+		levelColor = gray
 	case WarnLevel:
 		levelColor = yellow
 	case ErrorLevel, FatalLevel, PanicLevel:
 		levelColor = red
+	case InfoLevel:
+		levelColor = blue
 	default:
 		levelColor = blue
 	}
 
-	levelText := strings.ToUpper(entry.Level.String())[0:4]
+	levelText := strings.ToUpper(entry.Level.String())
+	if !f.DisableLevelTruncation && !f.PadLevelText {
+		levelText = levelText[0:4]
+	}
+	if f.PadLevelText {
+		// Generates the format string used in the next line, for example "%-6s" or "%-7s".
+		// Based on the max level text length.
+		formatString := "%-" + strconv.Itoa(f.levelTextMaxLength) + "s"
+		// Formats the level text by appending spaces up to the max length, for example:
+		// 	- "INFO   "
+		//	- "WARNING"
+		levelText = fmt.Sprintf(formatString, levelText)
+	}
 
-	fmt.Fprintf(b, "\x1b[%dm%s\x1b[0m[%04d] %-44s ", levelColor, levelText, miniTS(), entry.Message)
+	// Remove a single newline if it already exists in the message to keep
+	// the behavior of logrus text_formatter the same as the stdlib log package
+	entry.Message = strings.TrimSuffix(entry.Message, "\n")
+
+	caller := ""
+	if entry.HasCaller() {
+		funcVal := fmt.Sprintf("%s()", entry.Caller.Function)
+		fileVal := fmt.Sprintf("%s:%d", entry.Caller.File, entry.Caller.Line)
+
+		if f.CallerPrettyfier != nil {
+			funcVal, fileVal = f.CallerPrettyfier(entry.Caller)
+		}
+
+		if fileVal == "" {
+			caller = funcVal
+		} else if funcVal == "" {
+			caller = fileVal
+		} else {
+			caller = fileVal + " " + funcVal
+		}
+	}
+
+	switch {
+	case f.DisableTimestamp:
+		fmt.Fprintf(b, "\x1b[%dm%s\x1b[0m%s %-44s ", levelColor, levelText, caller, entry.Message)
+	case !f.FullTimestamp:
+		fmt.Fprintf(b, "\x1b[%dm%s\x1b[0m[%04d]%s %-44s ", levelColor, levelText, int(entry.Time.Sub(baseTimestamp)/time.Second), caller, entry.Message)
+	default:
+		fmt.Fprintf(b, "\x1b[%dm%s\x1b[0m[%s]%s %-44s ", levelColor, levelText, entry.Time.Format(timestampFormat), caller, entry.Message)
+	}
 	for _, k := range keys {
-		v := entry.Data[k]
+		v := data[k]
-		fmt.Fprintf(b, " \x1b[%dm%s\x1b[0m=%v", levelColor, k, v)
+		fmt.Fprintf(b, " \x1b[%dm%s\x1b[0m=", levelColor, k)
+		f.appendValue(b, v)
 	}
 }
 
-func needsQuoting(text string) bool {
+func (f *TextFormatter) needsQuoting(text string) bool {
+	if f.ForceQuote {
+		return true
+	}
+	if f.QuoteEmptyFields && len(text) == 0 {
+		return true
+	}
+	if f.DisableQuote {
+		return false
+	}
 	for _, ch := range text {
 		if !((ch >= 'a' && ch <= 'z') ||
 			(ch >= 'A' && ch <= 'Z') ||
-			(ch >= '0' && ch < '9') ||
+			(ch >= '0' && ch <= '9') ||
-			ch == '-' || ch == '.') {
+			ch == '-' || ch == '.' || ch == '_' || ch == '/' || ch == '@' || ch == '^' || ch == '+') {
-			return false
+			return true
 		}
 	}
-	return true
+	return false
 }
 
-func (f *TextFormatter) appendKeyValue(b *bytes.Buffer, key, value interface{}) {
+func (f *TextFormatter) appendKeyValue(b *bytes.Buffer, key string, value interface{}) {
-	switch value.(type) {
+	if b.Len() > 0 {
-	case string:
+		b.WriteByte(' ')
-		if needsQuoting(value.(string)) {
+	}
-			fmt.Fprintf(b, "%v=%s ", key, value)
+	b.WriteString(key)
-		} else {
+	b.WriteByte('=')
-			fmt.Fprintf(b, "%v=%q ", key, value)
+	f.appendValue(b, value)
-		}
+}
-	case error:
+
-		if needsQuoting(value.(error).Error()) {
+func (f *TextFormatter) appendValue(b *bytes.Buffer, value interface{}) {
-			fmt.Fprintf(b, "%v=%s ", key, value)
+	stringVal, ok := value.(string)
-		} else {
+	if !ok {
-			fmt.Fprintf(b, "%v=%q ", key, value)
+		stringVal = fmt.Sprint(value)
-		}
+	}
-	default:
+
-		fmt.Fprintf(b, "%v=%v ", key, value)
+	if !f.needsQuoting(stringVal) {
+		b.WriteString(stringVal)
+	} else {
+		b.WriteString(fmt.Sprintf("%q", stringVal))
 	}
 }

text_formatter_test.go

@@ -3,17 +3,44 @@ package logrus
 import (
 	"bytes"
 	"errors"
-
+	"fmt"
+	"os"
+	"runtime"
+	"sort"
+	"strings"
 	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
+func TestFormatting(t *testing.T) {
+	tf := &TextFormatter{DisableColors: true}
+
+	testCases := []struct {
+		value    string
+		expected string
+	}{
+		{`foo`, "time=\"0001-01-01T00:00:00Z\" level=panic test=foo\n"},
+	}
+
+	for _, tc := range testCases {
+		b, _ := tf.Format(WithField("test", tc.value))
+
+		if string(b) != tc.expected {
+			t.Errorf("formatting expected for %q (result was %q instead of %q)", tc.value, string(b), tc.expected)
+		}
+	}
+}
+
 func TestQuoting(t *testing.T) {
 	tf := &TextFormatter{DisableColors: true}
 
 	checkQuoting := func(q bool, value interface{}) {
 		b, _ := tf.Format(WithField("test", value))
 		idx := bytes.Index(b, ([]byte)("test="))
-		cont := bytes.Contains(b[idx+5:], []byte{'"'})
+		cont := bytes.Contains(b[idx+5:], []byte("\""))
 		if cont != q {
 			if q {
 				t.Errorf("quoting expected for: %#v", value)
@@ -23,11 +50,551 @@ func TestQuoting(t *testing.T) {
 		}
 	}
 
+	checkQuoting(false, "")
 	checkQuoting(false, "abcd")
 	checkQuoting(false, "v1.0")
-	checkQuoting(true, "/foobar")
+	checkQuoting(false, "1234567890")
+	checkQuoting(false, "/foobar")
+	checkQuoting(false, "foo_bar")
+	checkQuoting(false, "foo@bar")
+	checkQuoting(false, "foobar^")
+	checkQuoting(false, "+/-_^@f.oobar")
+	checkQuoting(true, "foo\n\rbar")
+	checkQuoting(true, "foobar$")
+	checkQuoting(true, "&foobar")
 	checkQuoting(true, "x y")
 	checkQuoting(true, "x,y")
 	checkQuoting(false, errors.New("invalid"))
 	checkQuoting(true, errors.New("invalid argument"))
+
+	// Test for quoting empty fields.
+	tf.QuoteEmptyFields = true
+	checkQuoting(true, "")
+	checkQuoting(false, "abcd")
+	checkQuoting(true, "foo\n\rbar")
+	checkQuoting(true, errors.New("invalid argument"))
+
+	// Test forcing quotes.
+	tf.ForceQuote = true
+	checkQuoting(true, "")
+	checkQuoting(true, "abcd")
+	checkQuoting(true, "foo\n\rbar")
+	checkQuoting(true, errors.New("invalid argument"))
+
+	// Test forcing quotes when also disabling them.
+	tf.DisableQuote = true
+	checkQuoting(true, "")
+	checkQuoting(true, "abcd")
+	checkQuoting(true, "foo\n\rbar")
+	checkQuoting(true, errors.New("invalid argument"))
+
+	// Test disabling quotes
+	tf.ForceQuote = false
+	tf.QuoteEmptyFields = false
+	checkQuoting(false, "")
+	checkQuoting(false, "abcd")
+	checkQuoting(false, "foo\n\rbar")
+	checkQuoting(false, errors.New("invalid argument"))
+}
+
+func TestEscaping(t *testing.T) {
+	tf := &TextFormatter{DisableColors: true}
+
+	testCases := []struct {
+		value    string
+		expected string
+	}{
+		{`ba"r`, `ba\"r`},
+		{`ba'r`, `ba'r`},
+	}
+
+	for _, tc := range testCases {
+		b, _ := tf.Format(WithField("test", tc.value))
+		if !bytes.Contains(b, []byte(tc.expected)) {
+			t.Errorf("escaping expected for %q (result was %q instead of %q)", tc.value, string(b), tc.expected)
+		}
+	}
+}
+
+func TestEscaping_Interface(t *testing.T) {
+	tf := &TextFormatter{DisableColors: true}
+
+	ts := time.Now()
+
+	testCases := []struct {
+		value    interface{}
+		expected string
+	}{
+		{ts, fmt.Sprintf("\"%s\"", ts.String())},
+		{errors.New("error: something went wrong"), "\"error: something went wrong\""},
+	}
+
+	for _, tc := range testCases {
+		b, _ := tf.Format(WithField("test", tc.value))
+		if !bytes.Contains(b, []byte(tc.expected)) {
+			t.Errorf("escaping expected for %q (result was %q instead of %q)", tc.value, string(b), tc.expected)
+		}
+	}
+}
+
+func TestTimestampFormat(t *testing.T) {
+	checkTimeStr := func(format string) {
+		customFormatter := &TextFormatter{DisableColors: true, TimestampFormat: format}
+		customStr, _ := customFormatter.Format(WithField("test", "test"))
+		timeStart := bytes.Index(customStr, ([]byte)("time="))
+		timeEnd := bytes.Index(customStr, ([]byte)("level="))
+		timeStr := customStr[timeStart+5+len("\"") : timeEnd-1-len("\"")]
+		if format == "" {
+			format = time.RFC3339
+		}
+		_, e := time.Parse(format, (string)(timeStr))
+		if e != nil {
+			t.Errorf("time string \"%s\" did not match provided time format \"%s\": %s", timeStr, format, e)
+		}
+	}
+
+	checkTimeStr("2006-01-02T15:04:05.000000000Z07:00")
+	checkTimeStr("Mon Jan _2 15:04:05 2006")
+	checkTimeStr("")
+}
+
+func TestDisableLevelTruncation(t *testing.T) {
+	entry := &Entry{
+		Time:    time.Now(),
+		Message: "testing",
+	}
+	keys := []string{}
+	timestampFormat := "Mon Jan 2 15:04:05 -0700 MST 2006"
+	checkDisableTruncation := func(disabled bool, level Level) {
+		tf := &TextFormatter{DisableLevelTruncation: disabled}
+		var b bytes.Buffer
+		entry.Level = level
+		tf.printColored(&b, entry, keys, nil, timestampFormat)
+		logLine := (&b).String()
+		if disabled {
+			expected := strings.ToUpper(level.String())
+			if !strings.Contains(logLine, expected) {
+				t.Errorf("level string expected to be %s when truncation disabled", expected)
+			}
+		} else {
+			expected := strings.ToUpper(level.String())
+			if len(level.String()) > 4 {
+				if strings.Contains(logLine, expected) {
+					t.Errorf("level string %s expected to be truncated to %s when truncation is enabled", expected, expected[0:4])
+				}
+			} else {
+				if !strings.Contains(logLine, expected) {
+					t.Errorf("level string expected to be %s when truncation is enabled and level string is below truncation threshold", expected)
+				}
+			}
+		}
+	}
+
+	checkDisableTruncation(true, DebugLevel)
+	checkDisableTruncation(true, InfoLevel)
+	checkDisableTruncation(false, ErrorLevel)
+	checkDisableTruncation(false, InfoLevel)
+}
+
+func TestPadLevelText(t *testing.T) {
+	// A note for future maintainers / committers:
+	//
+	// This test denormalizes the level text as a part of its assertions.
+	// Because of that, its not really a "unit test" of the PadLevelText functionality.
+	// So! Many apologies to the potential future person who has to rewrite this test
+	// when they are changing some completely unrelated functionality.
+	params := []struct {
+		name            string
+		level           Level
+		paddedLevelText string
+	}{
+		{
+			name:            "PanicLevel",
+			level:           PanicLevel,
+			paddedLevelText: "PANIC  ", // 2 extra spaces
+		},
+		{
+			name:            "FatalLevel",
+			level:           FatalLevel,
+			paddedLevelText: "FATAL  ", // 2 extra spaces
+		},
+		{
+			name:            "ErrorLevel",
+			level:           ErrorLevel,
+			paddedLevelText: "ERROR  ", // 2 extra spaces
+		},
+		{
+			name:  "WarnLevel",
+			level: WarnLevel,
+			// WARNING is already the max length, so we don't need to assert a paddedLevelText
+		},
+		{
+			name:            "DebugLevel",
+			level:           DebugLevel,
+			paddedLevelText: "DEBUG  ", // 2 extra spaces
+		},
+		{
+			name:            "TraceLevel",
+			level:           TraceLevel,
+			paddedLevelText: "TRACE  ", // 2 extra spaces
+		},
+		{
+			name:            "InfoLevel",
+			level:           InfoLevel,
+			paddedLevelText: "INFO   ", // 3 extra spaces
+		},
+	}
+
+	// We create a "default" TextFormatter to do a control test.
+	// We also create a TextFormatter with PadLevelText, which is the parameter we want to do our most relevant assertions against.
+	tfDefault := TextFormatter{}
+	tfWithPadding := TextFormatter{PadLevelText: true}
+
+	for _, val := range params {
+		t.Run(val.name, func(t *testing.T) {
+			// TextFormatter writes into these bytes.Buffers, and we make assertions about their contents later
+			var bytesDefault bytes.Buffer
+			var bytesWithPadding bytes.Buffer
+
+			// The TextFormatter instance and the bytes.Buffer instance are different here
+			// all the other arguments are the same. We also initialize them so that they
+			// fill in the value of levelTextMaxLength.
+			tfDefault.init(&Entry{})
+			tfDefault.printColored(&bytesDefault, &Entry{Level: val.level}, []string{}, nil, "")
+			tfWithPadding.init(&Entry{})
+			tfWithPadding.printColored(&bytesWithPadding, &Entry{Level: val.level}, []string{}, nil, "")
+
+			// turn the bytes back into a string so that we can actually work with the data
+			logLineDefault := (&bytesDefault).String()
+			logLineWithPadding := (&bytesWithPadding).String()
+
+			// Control: the level text should not be padded by default
+			if val.paddedLevelText != "" && strings.Contains(logLineDefault, val.paddedLevelText) {
+				t.Errorf("log line %q should not contain the padded level text %q by default", logLineDefault, val.paddedLevelText)
+			}
+
+			// Assertion: the level text should still contain the string representation of the level
+			if !strings.Contains(strings.ToLower(logLineWithPadding), val.level.String()) {
+				t.Errorf("log line %q should contain the level text %q when padding is enabled", logLineWithPadding, val.level.String())
+			}
+
+			// Assertion: the level text should be in its padded form now
+			if val.paddedLevelText != "" && !strings.Contains(logLineWithPadding, val.paddedLevelText) {
+				t.Errorf("log line %q should contain the padded level text %q when padding is enabled", logLineWithPadding, val.paddedLevelText)
+			}
+
+		})
+	}
+}
+
+func TestDisableTimestampWithColoredOutput(t *testing.T) {
+	tf := &TextFormatter{DisableTimestamp: true, ForceColors: true}
+
+	b, _ := tf.Format(WithField("test", "test"))
+	if strings.Contains(string(b), "[0000]") {
+		t.Error("timestamp not expected when DisableTimestamp is true")
+	}
+}
+
+func TestNewlineBehavior(t *testing.T) {
+	tf := &TextFormatter{ForceColors: true}
+
+	// Ensure a single new line is removed as per stdlib log
+	e := NewEntry(StandardLogger())
+	e.Message = "test message\n"
+	b, _ := tf.Format(e)
+	if bytes.Contains(b, []byte("test message\n")) {
+		t.Error("first newline at end of Entry.Message resulted in unexpected 2 newlines in output. Expected newline to be removed.")
+	}
+
+	// Ensure a double new line is reduced to a single new line
+	e = NewEntry(StandardLogger())
+	e.Message = "test message\n\n"
+	b, _ = tf.Format(e)
+	if bytes.Contains(b, []byte("test message\n\n")) {
+		t.Error("Double newline at end of Entry.Message resulted in unexpected 2 newlines in output. Expected single newline")
+	}
+	if !bytes.Contains(b, []byte("test message\n")) {
+		t.Error("Double newline at end of Entry.Message did not result in a single newline after formatting")
+	}
+}
+
+func TestTextFormatterFieldMap(t *testing.T) {
+	formatter := &TextFormatter{
+		DisableColors: true,
+		FieldMap: FieldMap{
+			FieldKeyMsg:   "message",
+			FieldKeyLevel: "somelevel",
+			FieldKeyTime:  "timeywimey",
+		},
+	}
+
+	entry := &Entry{
+		Message: "oh hi",
+		Level:   WarnLevel,
+		Time:    time.Date(1981, time.February, 24, 4, 28, 3, 100, time.UTC),
+		Data: Fields{
+			"field1":     "f1",
+			"message":    "messagefield",
+			"somelevel":  "levelfield",
+			"timeywimey": "timeywimeyfield",
+		},
+	}
+
+	b, err := formatter.Format(entry)
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+
+	assert.Equal(t,
+		`timeywimey="1981-02-24T04:28:03Z" `+
+			`somelevel=warning `+
+			`message="oh hi" `+
+			`field1=f1 `+
+			`fields.message=messagefield `+
+			`fields.somelevel=levelfield `+
+			`fields.timeywimey=timeywimeyfield`+"\n",
+		string(b),
+		"Formatted output doesn't respect FieldMap")
+}
+
+func TestTextFormatterIsColored(t *testing.T) {
+	params := []struct {
+		name               string
+		expectedResult     bool
+		isTerminal         bool
+		disableColor       bool
+		forceColor         bool
+		envColor           bool
+		clicolorIsSet      bool
+		clicolorForceIsSet bool
+		clicolorVal        string
+		clicolorForceVal   string
+	}{
+		// Default values
+		{
+			name:               "testcase1",
+			expectedResult:     false,
+			isTerminal:         false,
+			disableColor:       false,
+			forceColor:         false,
+			envColor:           false,
+			clicolorIsSet:      false,
+			clicolorForceIsSet: false,
+		},
+		// Output on terminal
+		{
+			name:               "testcase2",
+			expectedResult:     true,
+			isTerminal:         true,
+			disableColor:       false,
+			forceColor:         false,
+			envColor:           false,
+			clicolorIsSet:      false,
+			clicolorForceIsSet: false,
+		},
+		// Output on terminal with color disabled
+		{
+			name:               "testcase3",
+			expectedResult:     false,
+			isTerminal:         true,
+			disableColor:       true,
+			forceColor:         false,
+			envColor:           false,
+			clicolorIsSet:      false,
+			clicolorForceIsSet: false,
+		},
+		// Output not on terminal with color disabled
+		{
+			name:               "testcase4",
+			expectedResult:     false,
+			isTerminal:         false,
+			disableColor:       true,
+			forceColor:         false,
+			envColor:           false,
+			clicolorIsSet:      false,
+			clicolorForceIsSet: false,
+		},
+		// Output not on terminal with color forced
+		{
+			name:               "testcase5",
+			expectedResult:     true,
+			isTerminal:         false,
+			disableColor:       false,
+			forceColor:         true,
+			envColor:           false,
+			clicolorIsSet:      false,
+			clicolorForceIsSet: false,
+		},
+		// Output on terminal with clicolor set to "0"
+		{
+			name:               "testcase6",
+			expectedResult:     false,
+			isTerminal:         true,
+			disableColor:       false,
+			forceColor:         false,
+			envColor:           true,
+			clicolorIsSet:      true,
+			clicolorForceIsSet: false,
+			clicolorVal:        "0",
+		},
+		// Output on terminal with clicolor set to "1"
+		{
+			name:               "testcase7",
+			expectedResult:     true,
+			isTerminal:         true,
+			disableColor:       false,
+			forceColor:         false,
+			envColor:           true,
+			clicolorIsSet:      true,
+			clicolorForceIsSet: false,
+			clicolorVal:        "1",
+		},
+		// Output not on terminal with clicolor set to "0"
+		{
+			name:               "testcase8",
+			expectedResult:     false,
+			isTerminal:         false,
+			disableColor:       false,
+			forceColor:         false,
+			envColor:           true,
+			clicolorIsSet:      true,
+			clicolorForceIsSet: false,
+			clicolorVal:        "0",
+		},
+		// Output not on terminal with clicolor set to "1"
+		{
+			name:               "testcase9",
+			expectedResult:     false,
+			isTerminal:         false,
+			disableColor:       false,
+			forceColor:         false,
+			envColor:           true,
+			clicolorIsSet:      true,
+			clicolorForceIsSet: false,
+			clicolorVal:        "1",
+		},
+		// Output not on terminal with clicolor set to "1" and force color
+		{
+			name:               "testcase10",
+			expectedResult:     true,
+			isTerminal:         false,
+			disableColor:       false,
+			forceColor:         true,
+			envColor:           true,
+			clicolorIsSet:      true,
+			clicolorForceIsSet: false,
+			clicolorVal:        "1",
+		},
+		// Output not on terminal with clicolor set to "0" and force color
+		{
+			name:               "testcase11",
+			expectedResult:     false,
+			isTerminal:         false,
+			disableColor:       false,
+			forceColor:         true,
+			envColor:           true,
+			clicolorIsSet:      true,
+			clicolorForceIsSet: false,
+			clicolorVal:        "0",
+		},
+		// Output not on terminal with clicolor_force set to "1"
+		{
+			name:               "testcase12",
+			expectedResult:     true,
+			isTerminal:         false,
+			disableColor:       false,
+			forceColor:         false,
+			envColor:           true,
+			clicolorIsSet:      false,
+			clicolorForceIsSet: true,
+			clicolorForceVal:   "1",
+		},
+		// Output not on terminal with clicolor_force set to "0"
+		{
+			name:               "testcase13",
+			expectedResult:     false,
+			isTerminal:         false,
+			disableColor:       false,
+			forceColor:         false,
+			envColor:           true,
+			clicolorIsSet:      false,
+			clicolorForceIsSet: true,
+			clicolorForceVal:   "0",
+		},
+		// Output on terminal with clicolor_force set to "0"
+		{
+			name:               "testcase14",
+			expectedResult:     false,
+			isTerminal:         true,
+			disableColor:       false,
+			forceColor:         false,
+			envColor:           true,
+			clicolorIsSet:      false,
+			clicolorForceIsSet: true,
+			clicolorForceVal:   "0",
+		},
+	}
+
+	cleanenv := func() {
+		os.Unsetenv("CLICOLOR")
+		os.Unsetenv("CLICOLOR_FORCE")
+	}
+
+	defer cleanenv()
+
+	for _, val := range params {
+		t.Run("textformatter_"+val.name, func(subT *testing.T) {
+			tf := TextFormatter{
+				isTerminal:                val.isTerminal,
+				DisableColors:             val.disableColor,
+				ForceColors:               val.forceColor,
+				EnvironmentOverrideColors: val.envColor,
+			}
+			cleanenv()
+			if val.clicolorIsSet {
+				os.Setenv("CLICOLOR", val.clicolorVal)
+			}
+			if val.clicolorForceIsSet {
+				os.Setenv("CLICOLOR_FORCE", val.clicolorForceVal)
+			}
+			res := tf.isColored()
+			if runtime.GOOS == "windows" && !tf.ForceColors && !val.clicolorForceIsSet {
+				assert.Equal(subT, false, res)
+			} else {
+				assert.Equal(subT, val.expectedResult, res)
+			}
+		})
+	}
+}
+
+func TestCustomSorting(t *testing.T) {
+	formatter := &TextFormatter{
+		DisableColors: true,
+		SortingFunc: func(keys []string) {
+			sort.Slice(keys, func(i, j int) bool {
+				if keys[j] == "prefix" {
+					return false
+				}
+				if keys[i] == "prefix" {
+					return true
+				}
+				return strings.Compare(keys[i], keys[j]) == -1
+			})
+		},
+	}
+
+	entry := &Entry{
+		Message: "Testing custom sort function",
+		Time:    time.Now(),
+		Level:   InfoLevel,
+		Data: Fields{
+			"test":      "testvalue",
+			"prefix":    "the application prefix",
+			"blablabla": "blablabla",
+		},
+	}
+	b, err := formatter.Format(entry)
+	require.NoError(t, err)
+	require.True(t, strings.HasPrefix(string(b), "prefix="), "format output is %q", string(b))
 }

travis/cross_build.sh

@@ -0,0 +1,5 @@
+#!/bin/bash
+
+if [[ "$TRAVIS_GO_VERSION" =~ ^1\.13\. ]] && [[ "$TRAVIS_OS_NAME" == "linux" ]] && [[ "$GO111MODULE" == "on" ]]; then
+    $(go env GOPATH)/bin/gox -build-lib
+fi

travis/install.sh

@@ -0,0 +1,8 @@
+#!/bin/bash
+
+set -e
+
+# Install golanci 1.32.2
+if [[ "$TRAVIS_GO_VERSION" =~ ^1\.15\. ]]; then
+    curl -sfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh| sh -s -- -b $(go env GOPATH)/bin v1.32.2
+fi

writer.go

@@ -0,0 +1,70 @@
+package logrus
+
+import (
+	"bufio"
+	"io"
+	"runtime"
+)
+
+// Writer at INFO level. See WriterLevel for details.
+func (logger *Logger) Writer() *io.PipeWriter {
+	return logger.WriterLevel(InfoLevel)
+}
+
+// WriterLevel returns an io.Writer that can be used to write arbitrary text to
+// the logger at the given log level. Each line written to the writer will be
+// printed in the usual way using formatters and hooks. The writer is part of an
+// io.Pipe and it is the callers responsibility to close the writer when done.
+// This can be used to override the standard library logger easily.
+func (logger *Logger) WriterLevel(level Level) *io.PipeWriter {
+	return NewEntry(logger).WriterLevel(level)
+}
+
+func (entry *Entry) Writer() *io.PipeWriter {
+	return entry.WriterLevel(InfoLevel)
+}
+
+func (entry *Entry) WriterLevel(level Level) *io.PipeWriter {
+	reader, writer := io.Pipe()
+
+	var printFunc func(args ...interface{})
+
+	switch level {
+	case TraceLevel:
+		printFunc = entry.Trace
+	case DebugLevel:
+		printFunc = entry.Debug
+	case InfoLevel:
+		printFunc = entry.Info
+	case WarnLevel:
+		printFunc = entry.Warn
+	case ErrorLevel:
+		printFunc = entry.Error
+	case FatalLevel:
+		printFunc = entry.Fatal
+	case PanicLevel:
+		printFunc = entry.Panic
+	default:
+		printFunc = entry.Print
+	}
+
+	go entry.writerScanner(reader, printFunc)
+	runtime.SetFinalizer(writer, writerFinalizer)
+
+	return writer
+}
+
+func (entry *Entry) writerScanner(reader *io.PipeReader, printFunc func(args ...interface{})) {
+	scanner := bufio.NewScanner(reader)
+	for scanner.Scan() {
+		printFunc(scanner.Text())
+	}
+	if err := scanner.Err(); err != nil {
+		entry.Errorf("Error while reading from Writer: %s", err)
+	}
+	reader.Close()
+}
+
+func writerFinalizer(writer *io.PipeWriter) {
+	writer.Close()
+}

writer_test.go

@@ -0,0 +1,34 @@
+package logrus_test
+
+import (
+	"log"
+	"net/http"
+
+	"git.internal/re/logrus"
+)
+
+func ExampleLogger_Writer_httpServer() {
+	logger := logrus.New()
+	w := logger.Writer()
+	defer w.Close()
+
+	srv := http.Server{
+		// create a stdlib log.Logger that writes to
+		// logrus.Logger.
+		ErrorLog: log.New(w, "", 0),
+	}
+
+	if err := srv.ListenAndServe(); err != nil {
+		logger.Fatal(err)
+	}
+}
+
+func ExampleLogger_Writer_stdlib() {
+	logger := logrus.New()
+	logger.Formatter = &logrus.JSONFormatter{}
+
+	// Use logrus for standard log output
+	// Note that `log` here references stdlib's log
+	// Not logrus imported under the name `log`.
+	log.SetOutput(logger.Writer())
+}