diff --git a/README.md b/README.md index cad2676..1449967 100644 --- a/README.md +++ b/README.md @@ -1,67 +1,75 @@ # Logrus -Logrus is a simple, opinionated logging package for Go. It has three debugging -levels: +Logrus is a simple, opinionated logging package for Go. Features include: -* `LevelDebug`: Debugging, usually turned off for deploys. -* `LevelInfo`: Info, useful for monitoring in production. -* `LevelWarning`: Warnings that should definitely be noted. These are sent to - `airbrake`. -* `LevelFatal`: Fatal messages that causes the application to crash. These are - sent to `airbrake`. +* **Level logging**. Logrus has the levels: Debug, Info, Warning and Fatal. +* **Exceptions**. Warnings will log as an exception along with logging it to + out, without quitting. Fatal will do the same, but call `os.Exit(1)` after + emitting the exception. +* **JSON**. Logrus currently logs as JSON by default. -## Usage +The API is completely compatible with the Go standard lib logger, with only the +features above added. -The global logging level is set by: `logrus.Level = logrus.{LevelDebug,LevelWarning,LevelFatal}`. +## Motivation -Note that for `airbrake` to work, `airbrake.Endpoint` and `airbrake.ApiKey` -should be set. - -There is a global logger, which new loggers inherit their settings from when -created (see example below), such as the place to redirect output. Logging can -be done with the global logging module: +The motivation for this library came out of a pattern seen in Go applications me +and others have been writing with functions such as: ```go -logrus.Debug("Something debugworthy happened: %s", importantStuff) -logrus.Info("Something infoworthy happened: %s", importantStuff) +func reportFatalError(err error) { + airbrake.Notify(err) + log.Fatal(err) +} -logrus.Warning("Something bad happened: %s", importantStuff) -// Reports to Airbrake - -logrus.Fatal("Something fatal happened: %s", importantStuff) -// Reports to Airbrake -// Then exits +func reportWarning(err error) { + airbrake.Notify(err) +} ``` -Types are encouraged to include their own logging object. This allows to set a -context dependent prefix to know where a certain message is coming from, without -cluttering every single message with this. +JSON logging is excellent for parsing logs for analysis and troubleshooting. +It's supported natively by log aggregators such as logstash and Splunk. Logging +JSON with logrus with the `WithFields` and `WithField` API in logrus forces you +to think about what context to log, to provide valuable troubleshoot information +later. + +## Example ```go -type Walrus struct { - TuskSize uint64 - Sex bool - logger logrus.Logger -} +import ( + "github.com/Sirupsen/logrus" +) -func NewWalrus(tuskSize uint64, sex bool) *Walrus { - return &Walrus{ - TuskSize: tuskSize, - Sex: bool, - logger: logrus.NewLogger("Walrus"), - } -} +var logger logrus.New() +func main() { + logger.WithFields(Fields{ + "animal": "walrus", + "location": "New York Aquarium", + "weather": "rain", + "name": "Wally", + "event": "escape", + }).Info("Walrus has escaped the aquarium! Action required!") + // { + // "level": "info", + // "animal": "walrus", + // "location": "New York Aquarium", + // "weather":"rain", + // "name": "Wally", + // "event":"escape", + // "msg": "Walrus has escaped the aquarium! Action required!") + // "time": "2014-02-23 19:57:35.862271048 -0500 EST" + // } -func (walrus *Walrus) Mate(partner *Walrus) error { - if walrus.Sex == partner.Sex { - return errors.New("Incompatible mating partner.") - } - - walrus.logger.Info("Walrus with tusk sizes %d and %d are mating!", walrus.TuskSize, partner.TuskSize) - // Generates a logging message: [Info] [Walrus] Walrus with tusk sizes and are mating! - - // Walrus mating happens here - - return nil + logger.WithField("source", "kafka").Infof("Connection to Kafka failed with %s", "some error") + // { + // "level": "info", + // "source": "kafka", + // "msg": "Connection to Kafka failed with some error", + // "time": "2014-02-23 19:57:35.862271048 -0500 EST" + // } } ``` + +Using `Warning` and `Fatal` to log to `airbrake` requires setting +`airbrake.Endpoint` and `airbrake.ApiKey`. See +[tobi/airbrake-go](https://github.com/tobi/airbrake-go).