[prometheusexporter] Make metrics path configurable

Fixes open-telemetry#8810

Signed-off-by: Goutham Veeramachaneni <gouthamve@gmail.com>

CHANGELOG.md

@@ -19,6 +19,7 @@
 
 - `k8sclusterreceiver`: Validate that k8s API supports a resource before setting up a watcher for it (#9523)
 - `internal/stanza`: Add support for `remove` operator (#9524)
+- `prometheusexporter`: Add option to configure metrics path (#9239)
 
 ### 🧰 Bug fixes 🧰
 

exporter/prometheusexporter/README.md

@@ -12,6 +12,7 @@ The following settings are required:
 
 The following settings can be optionally configured:
 
+- `metrics_path` (default=`/metrics`): The URL under which the metrics are exposed.
 - `const_labels` (no default): key/values that are applied for every exported metric.
 - `namespace` (no default): if set, exports metrics under the provided value.
 - `send_timestamps` (default = `false`): if true, sends the timestamp of the underlying
@@ -26,6 +27,7 @@ Example:
 exporters:
   prometheus:
     endpoint: "1.2.3.4:1234"
+    metrics_path: "/metrics"
     namespace: test-space
     const_labels:
       label1: value1
@@ -34,4 +36,4 @@ exporters:
     metric_expiration: 180m
     resource_to_telemetry_conversion:
       enabled: true
-```
+```

exporter/prometheusexporter/config.go

@@ -31,6 +31,9 @@ type Config struct {
 	// Endpoint is the address on which the Prometheus scrape handler will be run on.
 	Endpoint string `mapstructure:"endpoint"`
 
+	// MetricsPath is the path under which the Prometheus handler serves metrics. /metrics by default.
+	MetricsPath string `mapstructure:"metrics_path"`
+
 	// Namespace if set, exports metrics under the provided value.
 	Namespace string `mapstructure:"namespace"`
 

exporter/prometheusexporter/config_test.go

@@ -41,17 +41,17 @@ func TestLoadConfig(t *testing.T) {
 	assert.Equal(t, e0, factory.CreateDefaultConfig())
 
 	e1 := cfg.Exporters[config.NewComponentIDWithName(typeStr, "2")]
-	assert.Equal(t, e1,
-		&Config{
-			ExporterSettings: config.NewExporterSettings(config.NewComponentIDWithName(typeStr, "2")),
-			Endpoint:         "1.2.3.4:1234",
-			Namespace:        "test-space",
-			ConstLabels: map[string]string{
-				"label1":        "value1",
-				"another label": "spaced value",
-			},
-			SendTimestamps:    true,
-			MetricExpiration:  60 * time.Minute,
-			skipSanitizeLabel: false,
-		})
+	assert.Equal(t, &Config{
+		ExporterSettings: config.NewExporterSettings(config.NewComponentIDWithName(typeStr, "2")),
+		Endpoint:         "1.2.3.4:1234",
+		MetricsPath:      "/metrics",
+		Namespace:        "test-space",
+		ConstLabels: map[string]string{
+			"label1":        "value1",
+			"another label": "spaced value",
+		},
+		SendTimestamps:    true,
+		MetricExpiration:  60 * time.Minute,
+		skipSanitizeLabel: false,
+	}, e1)
 }

exporter/prometheusexporter/end_to_end_test.go

@@ -70,6 +70,7 @@ func TestEndToEndSummarySupport(t *testing.T) {
 		ExporterSettings: config.NewExporterSettings(config.NewComponentID(typeStr)),
 		Namespace:        "test",
 		Endpoint:         ":8787",
+		MetricsPath:      "/metrics",
 		SendTimestamps:   true,
 		MetricExpiration: 2 * time.Hour,
 	}

exporter/prometheusexporter/factory.go

@@ -43,6 +43,7 @@ func NewFactory() component.ExporterFactory {
 func createDefaultConfig() config.Exporter {
 	return &Config{
 		ExporterSettings:  config.NewExporterSettings(config.NewComponentID(typeStr)),
+		MetricsPath:       "/metrics",
 		ConstLabels:       map[string]string{},
 		SendTimestamps:    false,
 		MetricExpiration:  time.Minute * 5,

exporter/prometheusexporter/prometheus.go

@@ -30,6 +30,7 @@ import (
 type prometheusExporter struct {
 	name         string
 	endpoint     string
+	metricsPath  string
 	shutdownFunc func() error
 	handler      http.Handler
 	collector    *collector
@@ -50,6 +51,7 @@ func newPrometheusExporter(config *Config, set component.ExporterCreateSettings)
 	return &prometheusExporter{
 		name:         config.ID().String(),
 		endpoint:     addr,
+		metricsPath:  config.MetricsPath,
 		collector:    collector,
 		registry:     registry,
 		shutdownFunc: func() error { return nil },
@@ -72,7 +74,7 @@ func (pe *prometheusExporter) Start(_ context.Context, _ component.Host) error {
 	pe.shutdownFunc = ln.Close
 
 	mux := http.NewServeMux()
-	mux.Handle("/metrics", pe.handler)
+	mux.Handle(pe.metricsPath, pe.handler)
 	srv := &http.Server{Handler: mux}
 	go func() {
 		_ = srv.Serve(ln)

exporter/prometheusexporter/prometheus_test.go

@@ -49,6 +49,7 @@ func TestPrometheusExporter(t *testing.T) {
 					"code0": "one0",
 				},
 				Endpoint:         ":8999",
+				MetricsPath:      "/metrics",
 				SendTimestamps:   false,
 				MetricExpiration: 60 * time.Second,
 			},
@@ -107,6 +108,7 @@ func TestPrometheusExporter_endToEnd(t *testing.T) {
 			"code1": "one1",
 		},
 		Endpoint:         ":7777",
+		MetricsPath:      "/metrics",
 		MetricExpiration: 120 * time.Minute,
 	}
 
@@ -182,6 +184,7 @@ func TestPrometheusExporter_endToEndWithTimestamps(t *testing.T) {
 			"code2": "one2",
 		},
 		Endpoint:         ":7777",
+		MetricsPath:      "/metrics",
 		SendTimestamps:   true,
 		MetricExpiration: 120 * time.Minute,
 	}
@@ -258,6 +261,7 @@ func TestPrometheusExporter_endToEndWithResource(t *testing.T) {
 			"code2": "one2",
 		},
 		Endpoint:         ":7777",
+		MetricsPath:      "/metrics",
 		SendTimestamps:   true,
 		MetricExpiration: 120 * time.Minute,
 		ResourceToTelemetrySettings: resourcetotelemetry.Settings{