Push http metrics through statsd

Add a statsd http middleware for negroni

Metrics:

- "flagr.http.requests.count" > total amount of requests
- "flagr.http.requests.duration" > duration of the requests (with
  nanosecond precision)

Tags:

- http status as "status"
- http uri as "path"
- http method as "method"

Author: marceloboeira

.gitattributes

@@ -0,0 +1,5 @@
+# All files use LF as eol
+* text=auto eol=lf
+
+# Remove vendor folder from the diff
+vendor/**/* -diff

Gopkg.lock

@@ -132,3 +132,7 @@
 [[constraint]]
   name = "github.com/bsm/ratelimit"
   version = "2.0.0"
+
+[[constraint]]
+  name = "github.com/DataDog/datadog-go"
+  version = "2.1.0"

Gopkg.toml

@@ -41,17 +41,17 @@ Or try it on [https://try-flagr.herokuapp.com](https://try-flagr.herokuapp.com)
 
 ```
 curl --request POST \
-  --url https://try-flagr.herokuapp.com/api/v1/evaluation \
-  --header 'content-type: application/json' \
-  --data '{
-	"entityID": "127",
-	"entityType": "user",
-	"entityContext": {
-		"state": "NY"
-	},
-	"flagID": 1,
-	"enableDebug": true
-}'
+       --url https://try-flagr.herokuapp.com/api/v1/evaluation \
+       --header 'content-type: application/json' \
+       --data '{
+         "entityID": "127",
+           "entityType": "user",
+           "entityContext": {
+             "state": "NY"
+           },
+           "flagID": 1,
+           "enableDebug": true
+       }'
 ```
 
 

README.md

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"os"
 
+	"github.com/DataDog/datadog-go/statsd"
 	"github.com/caarlos0/env"
 	"github.com/evalphobia/logrus_sentry"
 	raven "github.com/getsentry/raven-go"
@@ -13,14 +14,16 @@ import (
 
 // Global is the global dependency we can use, such as the new relic app instance
 var Global = struct {
-	NewrelicApp newrelic.Application
+	NewrelicApp  newrelic.Application
+	StatsdClient *statsd.Client
 }{}
 
 func init() {
 	env.Parse(&Config)
 
 	setupSentry()
 	setupLogrus()
+	setupStatsd()
 	setupNewrelic()
 }
 
@@ -45,6 +48,18 @@ func setupSentry() {
 	}
 }
 
+func setupStatsd() {
+	if Config.StatsdEnabled {
+		client, err := statsd.New(fmt.Sprintf("%s:%s", Config.StatsdHost, Config.StatsdPort))
+		if err != nil {
+			panic(fmt.Sprintf("unable to initialize statsd. %s", err))
+		}
+		client.Namespace = Config.StatsdPrefix
+
+		Global.StatsdClient = client
+	}
+}
+
 func setupNewrelic() {
 	if Config.NewRelicEnabled {
 		nCfg := newrelic.NewConfig(Config.NewRelicAppName, Config.NewRelicKey)

pkg/config/config.go

@@ -47,6 +47,12 @@ var Config = struct {
 	NewRelicAppName string `env:"FLAGR_NEWRELIC_NAME" envDefault:"flagr"`
 	NewRelicKey     string `env:"FLAGR_NEWRELIC_KEY" envDefault:""`
 
+	// StatsdEnabled - enable statsd metrics for all the endpoints and DB operations
+	StatsdEnabled bool   `env:"FLAGR_STATSD_ENABLED" envDefault:"false"`
+	StatsdHost    string `env:"FLAGR_STATSD_HOST" envDefault:"127.0.0.1"`
+	StatsdPort    string `env:"FLAGR_STATSD_PORT" envDefault:"8125"`
+	StatsdPrefix  string `env:"FLAGR_STATSD_PREFIX" envDefault:"flagr."`
+
 	// EvalCacheRefreshTimeout - timeout of getting the flags data from DB into the in-memory evaluation cache
 	EvalCacheRefreshTimeout time.Duration `env:"FLAGR_EVALCACHE_REFRESHTIMEOUT" envDefault:"59s"`
 	// EvalCacheRefreshInterval - time interval of getting the flags data from DB into the in-memory evaluation cache

pkg/config/env.go

@@ -3,8 +3,11 @@ package config
 import (
 	"net/http"
 	"os"
+	"strconv"
 	"strings"
+	"time"
 
+	"github.com/DataDog/datadog-go/statsd"
 	jwtmiddleware "github.com/auth0/go-jwt-middleware"
 	"github.com/dgrijalva/jwt-go"
 	"github.com/gohttp/pprof"
@@ -28,6 +31,10 @@ func SetupGlobalMiddleware(handler http.Handler) http.Handler {
 		}))
 	}
 
+	if Config.StatsdEnabled {
+		n.Use(&statsdMiddleware{StatsdClient: Global.StatsdClient})
+	}
+
 	if Config.NewRelicEnabled {
 		n.Use(&negroninewrelic.Newrelic{Application: &Global.NewrelicApp})
 	}
@@ -87,3 +94,25 @@ func (a *auth) ServeHTTP(w http.ResponseWriter, req *http.Request, next http.Han
 	}
 	a.JWTMiddleware.HandlerWithNext(w, req, next)
 }
+
+type statsdMiddleware struct {
+	StatsdClient *statsd.Client
+}
+
+func (s *statsdMiddleware) ServeHTTP(w http.ResponseWriter, r *http.Request, next http.HandlerFunc) {
+	defer func(start time.Time) {
+		response := w.(negroni.ResponseWriter)
+		status := strconv.Itoa(response.Status())
+		duration := float64(time.Since(start)) / float64(time.Millisecond)
+		tags := []string{
+			"status:" + status,
+			"path:" + r.RequestURI,
+			"method:" + r.Method,
+		}
+
+		s.StatsdClient.Incr("http.requests.count", tags, 1)
+		s.StatsdClient.TimeInMilliseconds("http.requests.duration", duration, tags, 1)
+	}(time.Now())
+
+	next(w, r)
+}

pkg/config/middleware.go

@@ -8,7 +8,6 @@ import (
 )
 
 var validatePutDistributions = func(params distribution.PutDistributionsParams) *Error {
-
 	sum := int64(0)
 	for _, d := range params.Body.Distributions {
 		if d.Percent == nil {