chore(tracing): Update control plane to OpenTelemetry

The control plane tracing is meant mostly for development, but it's using an outdated export protocol that isn't supported basically anywhere.

This updates the control plane to OpenTelemetry for internal tracing and OTLP gRPC as the export protocol.

Author: sfleen

cli/cmd/policy.go

@@ -15,7 +15,7 @@ import (
 	pkgcmd "github.com/linkerd/linkerd2/pkg/cmd"
 	"github.com/linkerd/linkerd2/pkg/k8s"
 	"github.com/spf13/cobra"
-	"go.opencensus.io/plugin/ocgrpc"
+	"go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials/insecure"
 )
@@ -89,7 +89,7 @@ displayed.`,
 				}
 			}
 
-			conn, err := grpc.NewClient(apiAddr, grpc.WithTransportCredentials(insecure.NewCredentials()), grpc.WithStatsHandler(&ocgrpc.ClientHandler{}))
+			conn, err := grpc.NewClient(apiAddr, grpc.WithTransportCredentials(insecure.NewCredentials()), grpc.WithStatsHandler(otelgrpc.NewClientHandler()))
 			if err != nil {
 				return err
 			}

controller/api/destination/client.go

@@ -2,10 +2,9 @@ package destination
 
 import (
 	"context"
-
 	pb "github.com/linkerd/linkerd2-proxy-api/go/destination"
 	"github.com/linkerd/linkerd2/pkg/k8s"
-	"go.opencensus.io/plugin/ocgrpc"
+	"go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials/insecure"
 )
@@ -18,7 +17,7 @@ const (
 // NewClient creates a client for the control plane Destination API that
 // implements the Destination service.
 func NewClient(addr string) (pb.DestinationClient, *grpc.ClientConn, error) {
-	conn, err := grpc.NewClient(addr, grpc.WithTransportCredentials(insecure.NewCredentials()), grpc.WithStatsHandler(&ocgrpc.ClientHandler{}))
+	conn, err := grpc.NewClient(addr, grpc.WithTransportCredentials(insecure.NewCredentials()), grpc.WithStatsHandler(otelgrpc.NewClientHandler()))
 	if err != nil {
 		return nil, nil, err
 	}

go.mod

@@ -3,7 +3,6 @@ module github.com/linkerd/linkerd2
 go 1.25.0
 
 require (
-	contrib.go.opencensus.io/exporter/ocagent v0.7.0
 	dario.cat/mergo v1.0.2
 	github.com/AdaLogics/go-fuzz-headers v0.0.0-20230811130428-ced1acdcaa24
 	github.com/bombsimon/logrusr/v4 v4.1.0
@@ -34,7 +33,10 @@ require (
 	github.com/sirupsen/logrus v1.9.3
 	github.com/spf13/cobra v1.10.1
 	github.com/spf13/pflag v1.0.10
-	go.opencensus.io v0.24.0
+	go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.60.0
+	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.58.0
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.34.0
+	go.opentelemetry.io/otel/sdk v1.37.0
 	golang.org/x/net v0.46.0
 	golang.org/x/tools v0.38.0
 	google.golang.org/grpc v1.76.0
@@ -55,6 +57,16 @@ require (
 	sigs.k8s.io/yaml v1.6.0
 )
 
+require (
+	github.com/cenkalti/backoff/v4 v4.3.0 // indirect
+	github.com/felixge/httpsnoop v1.0.4 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	go.opentelemetry.io/auto/sdk v1.1.0 // indirect
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.34.0 // indirect
+	go.opentelemetry.io/otel/metric v1.38.0 // indirect
+	go.opentelemetry.io/proto/otlp v1.5.0 // indirect
+)
+
 require (
 	github.com/Azure/go-ansiterm v0.0.0-20250102033503-faa5f7b0171c // indirect
 	github.com/BurntSushi/toml v1.5.0 // indirect
@@ -64,7 +76,6 @@ require (
 	github.com/Masterminds/sprig/v3 v3.3.0 // indirect
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/blang/semver/v4 v4.0.0 // indirect
-	github.com/census-instrumentation/opencensus-proto v0.4.1 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/chai2010/gettext-go v1.0.2 // indirect
 	github.com/clipperhouse/uax29/v2 v2.2.0 // indirect
@@ -92,7 +103,6 @@ require (
 	github.com/go-openapi/swag/yamlutils v0.25.1 // indirect
 	github.com/gobwas/glob v0.2.3 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect
-	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
 	github.com/google/btree v1.1.3 // indirect
 	github.com/google/gnostic-models v0.7.0 // indirect
 	github.com/google/go-cmp v0.7.0 // indirect
@@ -134,8 +144,8 @@ require (
 	github.com/spf13/cast v1.7.0 // indirect
 	github.com/x448/float16 v0.8.4 // indirect
 	github.com/xlab/treeprint v1.2.0 // indirect
-	go.opentelemetry.io/otel v1.37.0 // indirect
-	go.opentelemetry.io/otel/trace v1.37.0 // indirect
+	go.opentelemetry.io/otel v1.38.0
+	go.opentelemetry.io/otel/trace v1.38.0 // indirect
 	go.yaml.in/yaml/v2 v2.4.3 // indirect
 	go.yaml.in/yaml/v3 v3.0.4 // indirect
 	golang.org/x/crypto v0.43.0 // indirect
@@ -149,7 +159,6 @@ require (
 	golang.org/x/time v0.12.0 // indirect
 	golang.org/x/tools/go/packages/packagestest v0.1.1-deprecated // indirect
 	golang.org/x/tools/godoc v0.1.0-deprecated // indirect
-	google.golang.org/api v0.143.0 // indirect
 	google.golang.org/genproto/googleapis/api v0.0.0-20250804133106-a7a43d27e69b // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20250804133106-a7a43d27e69b // indirect
 	gopkg.in/evanphx/json-patch.v4 v4.12.0 // indirect