client_golang/prometheus/registry.go

264 lines
7.2 KiB
Go

// Copyright (c) 2013, Prometheus Team
// All rights reserved.
//
// Use of this source code is governed by a BSD-style license that can be found
// in the LICENSE file.
package prometheus
import (
"compress/gzip"
"encoding/base64"
"encoding/json"
"flag"
"fmt"
"io"
"log"
"net/http"
"sort"
"strings"
"sync"
"time"
)
const (
acceptEncodingHeader = "Accept-Encoding"
authorization = "Authorization"
authorizationHeader = "WWW-Authenticate"
authorizationHeaderValue = "Basic"
contentEncodingHeader = "Content-Encoding"
contentTypeHeader = "Content-Type"
gzipAcceptEncodingValue = "gzip"
gzipContentEncodingValue = "gzip"
jsonContentType = "application/json"
jsonSuffix = ".json"
)
var (
abortOnMisuse bool
debugRegistration bool
useAggressiveSanityChecks bool
)
// container represents a top-level registered metric that encompasses its
// static metadata.
type container struct {
BaseLabels map[string]string `json:"baseLabels"`
Docstring string `json:"docstring"`
Metric Metric `json:"metric"`
name string
}
type registry struct {
mutex sync.RWMutex
signatureContainers map[string]container
}
// Registry is a registrar where metrics are listed.
//
// In most situations, using DefaultRegistry is sufficient versus creating one's
// own.
type Registry interface {
// Register a metric with a given name. Name should be globally unique.
Register(name, docstring string, baseLabels map[string]string, metric Metric) error
// Create a http.HandlerFunc that is tied to a Registry such that requests
// against it generate a representation of the housed metrics.
Handler() http.HandlerFunc
// This is a legacy version of Handler and is deprecated. Please stop
// using.
YieldExporter() http.HandlerFunc
}
// This builds a new metric registry. It is not needed in the majority of
// cases.
func NewRegistry() Registry {
return registry{
signatureContainers: make(map[string]container),
}
}
// Associate a Metric with the DefaultRegistry.
func Register(name, docstring string, baseLabels map[string]string, metric Metric) error {
return DefaultRegistry.Register(name, docstring, baseLabels, metric)
}
// Implements json.Marshaler
func (r registry) MarshalJSON() (_ []byte, err error) {
metrics := make([]interface{}, 0, len(r.signatureContainers))
keys := make([]string, 0, len(metrics))
for key := range r.signatureContainers {
keys = append(keys, key)
}
sort.Strings(keys)
for _, key := range keys {
metrics = append(metrics, r.signatureContainers[key])
}
return json.Marshal(metrics)
}
// isValidCandidate returns true if the candidate is acceptable for use. In the
// event of any apparent incorrect use it will report the problem, invalidate
// the candidate, or outright abort.
func (r registry) isValidCandidate(name string, baseLabels map[string]string) (signature string, err error) {
if len(name) == 0 {
err = fmt.Errorf("unnamed metric named with baseLabels %s is invalid", baseLabels)
if abortOnMisuse {
panic(err)
} else if debugRegistration {
log.Println(err)
}
}
if _, contains := baseLabels[nameLabel]; contains {
err = fmt.Errorf("metric named %s with baseLabels %s contains reserved label name %s in baseLabels", name, baseLabels, nameLabel)
if abortOnMisuse {
panic(err)
} else if debugRegistration {
log.Println(err)
}
return
}
baseLabels[nameLabel] = name
signature = labelsToSignature(baseLabels)
if _, contains := r.signatureContainers[signature]; contains {
err = fmt.Errorf("metric named %s with baseLabels %s is already registered", name, baseLabels)
if abortOnMisuse {
panic(err)
} else if debugRegistration {
log.Println(err)
}
return
}
if useAggressiveSanityChecks {
for _, container := range r.signatureContainers {
if container.name == name {
err = fmt.Errorf("metric named %s with baseLabels %s is already registered as %s and risks causing confusion", name, baseLabels, container.BaseLabels)
if abortOnMisuse {
panic(err)
} else if debugRegistration {
log.Println(err)
}
return
}
}
}
return
}
func (r registry) Register(name, docstring string, baseLabels map[string]string, metric Metric) (err error) {
r.mutex.Lock()
defer r.mutex.Unlock()
if baseLabels == nil {
baseLabels = map[string]string{}
}
signature, err := r.isValidCandidate(name, baseLabels)
if err != nil {
return
}
r.signatureContainers[signature] = container{
BaseLabels: baseLabels,
Docstring: docstring,
Metric: metric,
name: name,
}
return
}
// YieldBasicAuthExporter creates a http.HandlerFunc that is protected by HTTP's
// basic authentication.
func (register registry) YieldBasicAuthExporter(username, password string) http.HandlerFunc {
// XXX: Work with Daniel to get this removed from the library, as it is really
// superfluous and can be much more elegantly accomplished via
// delegation.
exporter := register.YieldExporter()
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
authenticated := false
if auth := r.Header.Get(authorization); auth != "" {
base64Encoded := strings.SplitAfter(auth, " ")[1]
decoded, err := base64.URLEncoding.DecodeString(base64Encoded)
if err == nil {
usernamePassword := strings.Split(string(decoded), ":")
if usernamePassword[0] == username && usernamePassword[1] == password {
authenticated = true
}
}
}
if authenticated {
exporter.ServeHTTP(w, r)
} else {
w.Header().Add(authorizationHeader, authorizationHeaderValue)
http.Error(w, "access forbidden", 401)
}
})
}
// decorateWriter annotates the response writer to handle any other behaviors
// that might be beneficial to the client---e.g., GZIP encoding.
func decorateWriter(request *http.Request, writer http.ResponseWriter) io.Writer {
if !strings.Contains(request.Header.Get(acceptEncodingHeader), gzipAcceptEncodingValue) {
return writer
}
writer.Header().Set(contentEncodingHeader, gzipContentEncodingValue)
gziper := gzip.NewWriter(writer)
return gziper
}
func (registry registry) YieldExporter() http.HandlerFunc {
log.Println("Registry.YieldExporter is deprecated in favor of Registry.Handler.")
return registry.Handler()
}
func (registry registry) Handler() http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
defer requestLatencyAccumulator(time.Now())
requestCount.Increment(nil)
url := r.URL
if strings.HasSuffix(url.Path, jsonSuffix) {
header := w.Header()
header.Set(ProtocolVersionHeader, APIVersion)
header.Set(contentTypeHeader, jsonContentType)
writer := decorateWriter(r, w)
if closer, ok := writer.(io.Closer); ok {
defer closer.Close()
}
json.NewEncoder(writer).Encode(registry)
} else {
w.WriteHeader(http.StatusNotFound)
}
}
}
func init() {
flag.BoolVar(&abortOnMisuse, FlagNamespace+"abortonmisuse", false, "abort if a semantic misuse is encountered (bool).")
flag.BoolVar(&debugRegistration, FlagNamespace+"debugregistration", false, "display information about the metric registration process (bool).")
flag.BoolVar(&useAggressiveSanityChecks, FlagNamespace+"useaggressivesanitychecks", false, "perform expensive validation of metrics (bool).")
}