Allow user to pass in metrics namespace

CHANGELOG.md

@@ -14,6 +14,7 @@
 
 - `ocb` now exits with an error if it fails to load the build configuration. (#5731)
 - Deprecate `HTTPClientSettings.ToClientWithHost` (#5737)
+- Add a new field `service.telemetry.metrics.namespace` to allow users to customize the collector's metric namespace (#5692)
 
 ### 🧰 Bug fixes 🧰
 

service/collector_test.go

@@ -267,6 +267,10 @@ func ownMetricsTestCases(version string) []ownMetricsTestCase {
 }
 
 func testCollectorStartHelper(t *testing.T, telemetry *telemetryInitializer, tc ownMetricsTestCase) {
+	testCollectorStartHelperWithConfig(t, telemetry, tc, "otelcol", "otelcol-nop.yaml")
+}
+
+func testCollectorStartHelperWithConfig(t *testing.T, telemetry *telemetryInitializer, tc ownMetricsTestCase, namespace, configFile string) {
 	factories, err := componenttest.NopFactories()
 	zpagesExt := zpagesextension.NewFactory()
 	factories.Extensions[zpagesExt.Type()] = zpagesExt
@@ -294,7 +298,7 @@ func testCollectorStartHelper(t *testing.T, telemetry *telemetryInitializer, tc
 		extraCfgAsProps["service::telemetry::resource::"+k] = v
 	}
 
-	cfgSet := newDefaultConfigProviderSettings([]string{filepath.Join("testdata", "otelcol-nop.yaml")})
+	cfgSet := newDefaultConfigProviderSettings([]string{filepath.Join("testdata", configFile)})
 	cfgSet.MapConverters = append([]confmap.Converter{
 		mapConverter{extraCfgAsProps}},
 		cfgSet.MapConverters...,
@@ -318,7 +322,7 @@ func testCollectorStartHelper(t *testing.T, telemetry *telemetryInitializer, tc
 	}, 2*time.Second, 200*time.Millisecond)
 	assert.True(t, loggingHookCalled)
 
-	assertMetrics(t, metricsAddr, tc.expectedLabels)
+	assertMetrics(t, metricsAddr, tc.expectedLabels, namespace)
 
 	assertZPages(t)
 	col.signalsChannel <- syscall.SIGTERM
@@ -335,6 +339,14 @@ func TestCollectorStartWithOpenCensusMetrics(t *testing.T) {
 	}
 }
 
+func TestCollectorStartWithMetricNamespace(t *testing.T) {
+	for _, tc := range ownMetricsTestCases("test version") {
+		t.Run(tc.name, func(t *testing.T) {
+			testCollectorStartHelperWithConfig(t, newColTelemetry(featuregate.NewRegistry()), tc, "customNamespace", "otelcol-metricnamespace.yaml")
+		})
+	}
+}
+
 func TestCollectorStartWithOpenTelemetryMetrics(t *testing.T) {
 	for _, tc := range ownMetricsTestCases("test version") {
 		t.Run(tc.name, func(t *testing.T) {
@@ -431,7 +443,7 @@ func TestCollectorClosedStateOnStartUpError(t *testing.T) {
 	assert.Equal(t, Closed, col.GetState())
 }
 
-func assertMetrics(t *testing.T, metricsAddr string, expectedLabels map[string]labelValue) {
+func assertMetrics(t *testing.T, metricsAddr string, expectedLabels map[string]labelValue, namespace string) {
 	client := &http.Client{}
 	resp, err := client.Get("http://" + metricsAddr + "/metrics")
 	require.NoError(t, err)
@@ -445,7 +457,7 @@ func assertMetrics(t *testing.T, metricsAddr string, expectedLabels map[string]l
 	parsed, err := parser.TextToMetricFamilies(reader)
 	require.NoError(t, err)
 
-	prefix := "otelcol"
+	prefix := namespace
 	for metricName, metricFamily := range parsed {
 		// require is used here so test fails with a single message.
 		require.True(

service/telemetry.go

@@ -54,6 +54,7 @@ const (
 	// useOtelForInternalMetricsfeatureGateID is the feature gate ID that controls whether the collector uses open
 	// telemetrySettings for internal metrics.
 	useOtelForInternalMetricsfeatureGateID = "telemetry.useOtelForInternalMetrics"
+	defaultNameSpace                       = "otelcol"
 )
 
 type telemetryInitializer struct {
@@ -173,8 +174,12 @@ func (tel *telemetryInitializer) initOpenCensus(cfg telemetry.Config, telAttrs m
 	}
 
 	// Until we can use a generic metrics exporter, default to Prometheus.
+	namespace := defaultNameSpace
+	if cfg.Metrics.Namespace != nil {
+		namespace = *cfg.Metrics.Namespace
+	}
 	opts := prometheus.Options{
-		Namespace: "otelcol",
+		Namespace: namespace,
 	}
 
 	opts.ConstLabels = make(map[string]string)

service/telemetry/config.go

@@ -102,4 +102,11 @@ type MetricsConfig struct {
 
 	// Address is the [address]:port that metrics exposition should be bound to.
 	Address string `mapstructure:"address"`
+
+	// Namespace indicates the telemetry namespace the service will set. If nil, a default value 'otelcol' is assigned.
+	// An example of how the value of Namespace would affect metrics name:
+	// - if Namespace not set: "otelcol_process_cpu_seconds"
+	// - if Namespace set to empty string: "process_cpu_seconds"
+	// - if Namespace set to other string(e.g: "custom_namespace"): "custom_namespace_process_cpu_seconds"
+	Namespace *string `mapstructure:"namespace"`
 }

service/testdata/otelcol-metricnamespace.yaml

@@ -0,0 +1,30 @@
+receivers:
+  nop:
+
+processors:
+  nop:
+
+exporters:
+  nop:
+
+extensions:
+  nop:
+
+service:
+  telemetry:
+    metrics:
+      namespace: customNamespace
+  extensions: [nop]
+  pipelines:
+    traces:
+      receivers: [nop]
+      processors: [nop]
+      exporters: [nop]
+    metrics:
+      receivers: [nop]
+      processors: [nop]
+      exporters: [nop]
+    logs:
+      receivers: [nop]
+      processors: [nop]
+      exporters: [nop]