add support for exporting internal metrics via OpenTelemetry library.

config/configtelemetry/configtelemetry.go

@@ -38,6 +38,8 @@ const (
 	metricsLevelCfg = "metrics-level"
 )
 
+const UseOpenTelemetryForInternalMetrics = false
+
 var metricsLevelPtr = new(Level)
 
 // Flags is a helper function to add telemetry config flags to the service that exposes

go.mod

@@ -23,8 +23,11 @@ require (
 	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.23.0
 	go.opentelemetry.io/contrib/zpages v0.23.0
 	go.opentelemetry.io/otel v1.0.0
+	go.opentelemetry.io/otel/exporters/prometheus v0.23.0
 	go.opentelemetry.io/otel/metric v0.23.0
 	go.opentelemetry.io/otel/sdk v1.0.0
+	go.opentelemetry.io/otel/sdk/export/metric v0.23.0
+	go.opentelemetry.io/otel/sdk/metric v0.23.0
 	go.opentelemetry.io/otel/trace v1.0.0
 	go.uber.org/atomic v1.9.0
 	go.uber.org/zap v1.19.1

go.sum

@@ -408,13 +408,19 @@ go.opentelemetry.io/contrib/zpages v0.23.0/go.mod h1:i5BVZTRftVMBmYLP/T++in2G5MA
 go.opentelemetry.io/otel v1.0.0-RC3/go.mod h1:Ka5j3ua8tZs4Rkq4Ex3hwgBgOchyPVq5S6P2lz//nKQ=
 go.opentelemetry.io/otel v1.0.0 h1:qTTn6x71GVBvoafHK/yaRUmFzI4LcONZD0/kXxl5PHI=
 go.opentelemetry.io/otel v1.0.0/go.mod h1:AjRVh9A5/5DE7S+mZtTR6t8vpKKryam+0lREnfmS4cg=
+go.opentelemetry.io/otel/exporters/prometheus v0.23.0 h1:ZFx1kUjUSBF7H1mTPHHOqglEDQsxYBrDnYZ8i41v3iE=
+go.opentelemetry.io/otel/exporters/prometheus v0.23.0/go.mod h1:kjCXbxQnnEm5l3HrUw4IPyuALu7Uqb/bEK7vWQnbd8s=
 go.opentelemetry.io/otel/internal/metric v0.23.0 h1:mPfzm9Iqhw7G2nDBmUAjFTfPqLZPbOW2k7QI57ITbaI=
 go.opentelemetry.io/otel/internal/metric v0.23.0/go.mod h1:z+RPiDJe30YnCrOhFGivwBS+DU1JU/PiLKkk4re2DNY=
 go.opentelemetry.io/otel/metric v0.23.0 h1:mYCcDxi60P4T27/0jchIDFa1WHEfQeU3zH9UEMpnj2c=
 go.opentelemetry.io/otel/metric v0.23.0/go.mod h1:G/Nn9InyNnIv7J6YVkQfpc0JCfKBNJaERBGw08nqmVQ=
 go.opentelemetry.io/otel/sdk v1.0.0-RC3/go.mod h1:78H6hyg2fka0NYT9fqGuFLvly2yCxiBXDJAgLKo/2Us=
 go.opentelemetry.io/otel/sdk v1.0.0 h1:BNPMYUONPNbLneMttKSjQhOTlFLOD9U22HNG1KrIN2Y=
 go.opentelemetry.io/otel/sdk v1.0.0/go.mod h1:PCrDHlSy5x1kjezSdL37PhbFUMjrsLRshJ2zCzeXwbM=
+go.opentelemetry.io/otel/sdk/export/metric v0.23.0 h1:7NeoKPPx6NdZBVHLEp/LY5Lq85Ff1WNZnuJkuRy+azw=
+go.opentelemetry.io/otel/sdk/export/metric v0.23.0/go.mod h1:SuMiREmKVRIwFKq73zvGTvwFpxb/ZAYkMfyqMoOtDqs=
+go.opentelemetry.io/otel/sdk/metric v0.23.0 h1:xlZhPbiue1+jjSFEth94q9QCmX8Q24mOtue9IAmlVyI=
+go.opentelemetry.io/otel/sdk/metric v0.23.0/go.mod h1:wa0sKK13eeIFW+0OFjcC3S1i7FTRRiLAXe1kjBVbhwg=
 go.opentelemetry.io/otel/trace v1.0.0-RC3/go.mod h1:VUt2TUYd8S2/ZRX09ZDFZQwn2RqfMB5MzO17jBojGxo=
 go.opentelemetry.io/otel/trace v1.0.0 h1:TSBr8GTEtKevYMG/2d21M989r5WJYVimhTHBKVEZuh4=
 go.opentelemetry.io/otel/trace v1.0.0/go.mod h1:PXTWqayeFUlJV1YDNhsJYB184+IvAH814St6o6ajzIs=

service/telemetry.go

@@ -24,6 +24,13 @@ import (
 	"contrib.go.opencensus.io/exporter/prometheus"
 	"github.com/google/uuid"
 	"go.opencensus.io/stats/view"
+	otelprometheus "go.opentelemetry.io/otel/exporters/prometheus"
+	"go.opentelemetry.io/otel/metric/global"
+	export "go.opentelemetry.io/otel/sdk/export/metric"
+	"go.opentelemetry.io/otel/sdk/metric/aggregator/histogram"
+	controller "go.opentelemetry.io/otel/sdk/metric/controller/basic"
+	processor "go.opentelemetry.io/otel/sdk/metric/processor/basic"
+	selector "go.opentelemetry.io/otel/sdk/metric/selector/simple"
 	"go.uber.org/zap"
 
 	"go.opentelemetry.io/collector/config/configtelemetry"
@@ -71,9 +78,56 @@ func (tel *colTelemetry) initOnce(asyncErrorChannel chan<- error, ballastSizeByt
 		return nil
 	}
 
+	var instanceID string
+	if telemetry.GetAddInstanceID() {
+		instanceUUID, _ := uuid.NewRandom()
+		instanceID = instanceUUID.String()
+	}
+
+	var pe http.Handler
+	if configtelemetry.UseOpenTelemetryForInternalMetrics {
+		otelHandler, err := tel.initOpenTelemetry()
+		if err != nil {
+			return err
+		}
+		pe = otelHandler
+	} else {
+		ocHandler, err := tel.initOpenCensus(level, instanceID, ballastSizeBytes)
+		if err != nil {
+			return err
+		}
+		pe = ocHandler
+	}
+
+	logger.Info(
+		"Serving Prometheus metrics",
+		zap.String("address", metricsAddr),
+		zap.Int8("level", int8(level)), // TODO: make it human friendly
+		zap.String(semconv.AttributeServiceInstanceID, instanceID),
+	)
+
+	mux := http.NewServeMux()
+	mux.Handle("/metrics", pe)
+
+	tel.server = &http.Server{
+		Addr:    metricsAddr,
+		Handler: mux,
+	}
+
+	go func() {
+		serveErr := tel.server.ListenAndServe()
+		if serveErr != nil && serveErr != http.ErrServerClosed {
+			asyncErrorChannel <- serveErr
+		}
+	}()
+
+	return nil
+}
+
+func (tel *colTelemetry) initOpenCensus(level configtelemetry.Level, instanceID string, ballastSizeBytes uint64) (http.Handler, error) {
 	processMetricsViews, err := telemetry2.NewProcessMetricsViews(ballastSizeBytes)
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	var views []*view.View
@@ -84,7 +138,7 @@ func (tel *colTelemetry) initOnce(asyncErrorChannel chan<- error, ballastSizeByt
 
 	tel.views = views
 	if err = view.Register(views...); err != nil {
-		return err
+		return nil, err
 	}
 
 	processMetricsViews.StartCollection()
@@ -94,45 +148,40 @@ func (tel *colTelemetry) initOnce(asyncErrorChannel chan<- error, ballastSizeByt
 		Namespace: telemetry.GetMetricsPrefix(),
 	}
 
-	var instanceID string
 	if telemetry.GetAddInstanceID() {
-		instanceUUID, _ := uuid.NewRandom()
-		instanceID = instanceUUID.String()
 		opts.ConstLabels = map[string]string{
 			sanitizePrometheusKey(semconv.AttributeServiceInstanceID): instanceID,
 		}
 	}
 
 	pe, err := prometheus.NewExporter(opts)
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	view.RegisterExporter(pe)
+	return pe, nil
+}
 
-	logger.Info(
-		"Serving Prometheus metrics",
-		zap.String("address", metricsAddr),
-		zap.Int8("level", int8(level)), // TODO: make it human friendly
-		zap.String(semconv.AttributeServiceInstanceID, instanceID),
+func (tel *colTelemetry) initOpenTelemetry() (http.Handler, error) {
+	config := otelprometheus.Config{}
+	c := controller.New(
+		processor.New(
+			selector.NewWithHistogramDistribution(
+				histogram.WithExplicitBoundaries(config.DefaultHistogramBoundaries),
+			),
+			export.CumulativeExportKindSelector(),
+			processor.WithMemory(true),
+		),
 	)
 
-	mux := http.NewServeMux()
-	mux.Handle("/metrics", pe)
-
-	tel.server = &http.Server{
-		Addr:    metricsAddr,
-		Handler: mux,
+	pe, err := otelprometheus.New(config, c)
+	if err != nil {
+		return nil, err
 	}
 
-	go func() {
-		serveErr := tel.server.ListenAndServe()
-		if serveErr != nil && serveErr != http.ErrServerClosed {
-			asyncErrorChannel <- serveErr
-		}
-	}()
-
-	return nil
+	global.SetMeterProvider(pe.MeterProvider())
+	return pe, err
 }
 
 func (tel *colTelemetry) shutdown() error {