Register opencensus bridge for go-cloud lib telemetry

internal/pkg/telemetry/metric/prometheus/prometheus.go

@@ -9,6 +9,7 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/bridge/opencensus"
 	export "go.opentelemetry.io/otel/exporters/prometheus"
 	"go.opentelemetry.io/otel/sdk/metric"
 	"go.opentelemetry.io/otel/sdk/resource"
@@ -56,6 +57,9 @@ func ServeMetrics(ctx context.Context, serviceName, listenAddr string, logger lo
 		return nil, err
 	}
 
+	// Register legacy OpenCensus metrics, for go-cloud (https://github.com/google/go-cloud/issues/2877)
+	exporter.RegisterProducer(opencensus.NewMetricProducer())
+
 	// Create HTTP metrics server
 	opts := promhttp.HandlerOpts{ErrorLog: &errLogger{logger: logger}}
 	handler := http.NewServeMux()

internal/pkg/telemetry/oteldd/oteldd.go

@@ -7,7 +7,9 @@ import (
 	"context"
 	"encoding/binary"
 
+	octrace "go.opencensus.io/trace"
 	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/bridge/opencensus"
 	"go.opentelemetry.io/otel/codes"
 	"go.opentelemetry.io/otel/trace"
 	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/ext"
@@ -43,6 +45,10 @@ func IsDataDogEnabled(envs env.Provider) bool {
 func NewProvider() trace.TracerProvider {
 	p := &TracerProvider{}
 	p.tracer = newTracer(p)
+
+	// Register legacy OpenCensus tracing for go-cloud (https://github.com/google/go-cloud/issues/2877).
+	octrace.DefaultTracer = opencensus.NewTracer(p.Tracer("otel.bridge.opencensus"))
+
 	return p
 }