Default to Prometheus metrics in Jaeger components and support it in HotROD

Signed-off-by: Yuri Shkuro <ys@uber.com>

Author: Yuri Shkuro

examples/hotrod/cmd/root.go

@@ -15,21 +15,21 @@
 package cmd
 
 import (
-	"fmt"
 	"math/rand"
 	"os"
 	"time"
 
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/spf13/cobra"
-	"github.com/spf13/viper"
 	"github.com/uber/jaeger-lib/metrics"
 	"github.com/uber/jaeger-lib/metrics/go-kit"
 	"github.com/uber/jaeger-lib/metrics/go-kit/expvar"
+	jprom "github.com/uber/jaeger-lib/metrics/prometheus"
 	"go.uber.org/zap"
 )
 
 var (
-	cfgFile        string
+	metricsBackend string
 	logger         *zap.Logger
 	metricsFactory metrics.Factory
 )
@@ -51,25 +51,21 @@ func Execute() {
 }
 
 func init() {
-	cobra.OnInitialize(initConfig)
+	RootCmd.PersistentFlags().StringVarP(&metricsBackend, "metrics", "m", "expvar", "Metrics backend (expvar|prometheus)")
+	rand.Seed(int64(time.Now().Nanosecond()))
 	logger, _ = zap.NewDevelopment()
-	metricsFactory = xkit.Wrap("", expvar.NewFactory(10)) // 10 buckets for histograms
+	cobra.OnInitialize(initMetrics)
 }
 
-// initConfig reads in config file and ENV variables if set.
-func initConfig() {
-	if cfgFile != "" { // enable ability to specify config file via flag
-		viper.SetConfigFile(cfgFile)
-	}
-
-	viper.SetConfigName(".jaeger-demo") // name of config file (without extension)
-	viper.AddConfigPath("$HOME")        // adding home directory as first search path
-	viper.AutomaticEnv()                // read in environment variables that match
-
-	// If a config file is found, read it in.
-	if err := viper.ReadInConfig(); err == nil {
-		fmt.Println("Using config file:", viper.ConfigFileUsed())
+// initMetrics is called before the command is executed.
+func initMetrics() {
+	if metricsBackend == "expvar" {
+		metricsFactory = xkit.Wrap("", expvar.NewFactory(10)) // 10 buckets for histograms
+		logger.Info("Using expvar as metrics backend")
+	} else if metricsBackend == "prometheus" {
+		metricsFactory = jprom.New(prometheus.DefaultRegisterer, nil)
+		logger.Info("Using Prometheus as metrics backend")
+	} else {
+		logger.Fatal("unsupported metrics backend " + metricsBackend)
 	}
-
-	rand.Seed(int64(time.Now().Nanosecond()))
 }

examples/hotrod/services/route/server.go

@@ -24,6 +24,7 @@ import (
 	"time"
 
 	"github.com/opentracing/opentracing-go"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"go.uber.org/zap"
 
 	"github.com/jaegertracing/jaeger/examples/hotrod/pkg/delay"
@@ -59,7 +60,8 @@ func (s *Server) Run() error {
 func (s *Server) createServeMux() http.Handler {
 	mux := tracing.NewServeMux(s.tracer)
 	mux.Handle("/route", http.HandlerFunc(s.route))
-	mux.Handle("/debug/vars", expvar.Handler()) // use exported handler
+	mux.Handle("/debug/vars", expvar.Handler()) // expvar
+	mux.Handle("/metrics", promhttp.Handler())  // Prometheus
 	return mux
 }
 

glide.lock

@@ -40,5 +40,9 @@ import:
   - metrics
 - package: github.com/olivere/elastic
   version: v5.0.39
+- package: github.com/spf13/pflag
+  version: ^1
 - package: github.com/spf13/cobra
+  version: 0.0.1
 - package: github.com/spf13/viper
+  version: ^1

glide.yaml

@@ -34,8 +34,8 @@ import (
 const (
 	metricsBackend        = "metrics-backend"
 	metricsHTTPRoute      = "metrics-http-route"
-	defaultMetricsBackend = "expvar"
-	defaultMetricsRoute   = "/debug/vars"
+	defaultMetricsBackend = "prometheus"
+	defaultMetricsRoute   = "/metrics"
 )
 
 var errUnknownBackend = errors.New("unknown metrics backend specified")