Remove support for expvar metrics

Signed-off-by: Joeyyy09 <imt_2021063@iiitm.ac.in>
jaegertracing · May 10, 2024 · 12fea50 · 12fea50
1 parent 5ddcaa9
commit 12fea50
Show file tree

Hide file tree

Showing 4 changed files with 8 additions and 40 deletions.
diff --git a/examples/hotrod/cmd/flags.go b/examples/hotrod/cmd/flags.go
@@ -38,11 +38,8 @@ var (
 	jaegerUI string
 )
 
-const expvarDepr = "(deprecated, will be removed after 2024-01-01 or in release v1.53.0, whichever is later) "
-
 // used by root command
 func addFlags(cmd *cobra.Command) {
-	cmd.PersistentFlags().StringVarP(&metricsBackend, "metrics", "m", "prometheus", expvarDepr+"Metrics backend (expvar|prometheus). ")
 	cmd.PersistentFlags().StringVarP(&otelExporter, "otel-exporter", "x", "otlp", "OpenTelemetry exporter (otlp|stdout)")
 
 	cmd.PersistentFlags().DurationVarP(&fixDBConnDelay, "fix-db-query-delay", "D", 300*time.Millisecond, "Average latency of MySQL DB query")
@@ -60,4 +57,6 @@ func addFlags(cmd *cobra.Command) {
 	cmd.PersistentFlags().StringVarP(&jaegerUI, "jaeger-ui", "j", "http://localhost:16686", "Address of Jaeger UI to create [find trace] links")
 
 	cmd.PersistentFlags().BoolVarP(&verbose, "verbose", "v", false, "Enables debug logging")
+	// Warning about expvar deprecation
+	logger.Warn("The 'metrics' CLI flag and expvar metrics backend are deprecated and will be removed. Prometheus will be used as the default and only metrics backend.")
 }
diff --git a/examples/hotrod/cmd/root.go b/examples/hotrod/cmd/root.go
@@ -24,7 +24,6 @@ import (
 
 	"github.com/jaegertracing/jaeger/examples/hotrod/services/config"
 	"github.com/jaegertracing/jaeger/internal/jaegerclientenv2otel"
-	"github.com/jaegertracing/jaeger/internal/metrics/expvar"
 	"github.com/jaegertracing/jaeger/internal/metrics/prometheus"
 	"github.com/jaegertracing/jaeger/pkg/metrics"
 )
@@ -70,16 +69,9 @@ func onInitialize() {
 
 	jaegerclientenv2otel.MapJaegerToOtelEnvVars(logger)
 
-	switch metricsBackend {
-	case "expvar":
-		metricsFactory = expvar.NewFactory(10) // 10 buckets for histograms
-		logger.Info("*** Using expvar as metrics backend " + expvarDepr)
-	case "prometheus":
-		metricsFactory = prometheus.New().Namespace(metrics.NSOptions{Name: "hotrod", Tags: nil})
-		logger.Info("Using Prometheus as metrics backend")
-	default:
-		logger.Fatal("unsupported metrics backend " + metricsBackend)
-	}
+	// Only configure Prometheus as the metrics backend
+	metricsFactory = prometheus.New().Namespace(metrics.NSOptions{Name: "hotrod", Tags: nil})
+	logger.Info("Using Prometheus as the metrics backend")
 	if config.MySQLGetDelay != fixDBConnDelay {
 		logger.Info("fix: overriding MySQL query delay", zap.Duration("old", config.MySQLGetDelay), zap.Duration("new", fixDBConnDelay))
 		config.MySQLGetDelay = fixDBConnDelay

diff --git a/internal/metrics/metricsbuilder/builder.go b/internal/metrics/metricsbuilder/builder.go
@@ -17,16 +17,13 @@ package metricsbuilder
 
 import (
 	"errors"
-	"expvar"
 	"flag"
-	"log"
 	"net/http"
 
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/spf13/viper"
 
-	jexpvar "github.com/jaegertracing/jaeger/internal/metrics/expvar"
 	jprom "github.com/jaegertracing/jaeger/internal/metrics/prometheus"
 	"github.com/jaegertracing/jaeger/pkg/metrics"
 )
@@ -47,14 +44,14 @@ type Builder struct {
 	handler   http.Handler
 }
 
-const expvarDepr = "(deprecated, will be removed after 2024-01-01 or in release v1.53.0, whichever is later) "
+// const expvarDepr = "(deprecated, will be removed after 2024-01-01 or in release v1.53.0, whichever is later) "
 
 // AddFlags adds flags for Builder.
 func AddFlags(flags *flag.FlagSet) {
 	flags.String(
 		metricsBackend,
 		defaultMetricsBackend,
-		"Defines which metrics backend to use for metrics reporting: prometheus, none, or expvar "+expvarDepr)
+		"Defines which metrics backend to use for metrics reporting: prometheus or none")
 	flags.String(
 		metricsHTTPRoute,
 		defaultMetricsRoute,
@@ -78,10 +75,7 @@ func (b *Builder) CreateMetricsFactory(namespace string) (metrics.Factory, error
 		return metricsFactory, nil
 	}
 	if b.Backend == "expvar" {
-		metricsFactory := jexpvar.NewFactory(10).Namespace(metrics.NSOptions{Name: namespace, Tags: nil})
-		b.handler = expvar.Handler()
-		log.Printf("using expvar as metrics backend " + expvarDepr)
-		return metricsFactory, nil
+		return nil, errors.New("expvar metrics backend is deprecated and no longer supported")
 	}
 	if b.Backend == "none" || b.Backend == "" {
 		return metrics.NullFactory, nil

diff --git a/internal/metrics/metricsbuilder/builder_test.go b/internal/metrics/metricsbuilder/builder_test.go
@@ -16,7 +16,6 @@
 package metricsbuilder
 
 import (
-	"expvar"
 	"flag"
 	"testing"
 
@@ -61,29 +60,13 @@ func TestBuilder(t *testing.T) {
 		}
 		t.FailNow()
 	}
-	assertExpVarCounter := func() {
-		var found expvar.KeyValue
-		expected := "foo.counter"
-		expvar.Do(func(kv expvar.KeyValue) {
-			if kv.Key == expected {
-				found = kv
-			}
-		})
-		assert.Equal(t, expected, found.Key)
-	}
 	testCases := []struct {
 		backend string
 		route   string
 		err     error
 		handler bool
 		assert  func()
 	}{
-		{
-			backend: "expvar",
-			route:   "/",
-			handler: true,
-			assert:  assertExpVarCounter,
-		},
 		{
 			backend: "prometheus",
 			route:   "/",