in kube-apiserver add otelhttp client and server wrappers

Author: dashpole

staging/src/k8s.io/apiserver/pkg/endpoints/filters/traces.go

@@ -0,0 +1,27 @@
+/*
+Copyright 2020 The Kubernetes Authors.
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package filters
+
+import (
+	"net/http"
+
+	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/propagators"
+)
+
+// WithTracing adds tracing to requests if the incoming request is sampled
+func WithTracing(handler http.Handler) http.Handler {
+	return otelhttp.NewHandler(handler, "KubernetesAPI", otelhttp.WithPropagators(otel.NewCompositeTextMapPropagator(propagators.TraceContext{}, propagators.Baggage{})))
+}

staging/src/k8s.io/apiserver/pkg/server/config.go

@@ -684,6 +684,7 @@ func DefaultBuildHandlerChain(apiHandler http.Handler, c *Config) http.Handler {
 	handler = genericfilters.WithTimeoutForNonLongRunningRequests(handler, c.LongRunningFunc, c.RequestTimeout)
 	handler = genericfilters.WithWaitGroup(handler, c.LongRunningFunc, c.HandlerChainWaitGroup)
 	handler = genericapifilters.WithRequestInfo(handler, c.RequestInfoResolver)
+	handler = genericapifilters.WithTracing(handler)
 	if c.SecureServing != nil && !c.SecureServing.DisableHTTP2 && c.GoawayChance > 0 {
 		handler = genericfilters.WithProbabilisticGoaway(handler, c.GoawayChance)
 	}

staging/src/k8s.io/client-go/transport/round_trippers.go

@@ -22,6 +22,10 @@ import (
 	"strings"
 	"time"
 
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/propagators"
+
+	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
 	"golang.org/x/oauth2"
 	"k8s.io/klog/v2"
 
@@ -61,9 +65,27 @@ func HTTPWrappersForConfig(config *Config, rt http.RoundTripper) (http.RoundTrip
 		len(config.Impersonate.Extra) > 0 {
 		rt = NewImpersonatingRoundTripper(config.Impersonate, rt)
 	}
+	rt = NewOtelRoundTripper(rt)
 	return rt, nil
 }
 
+type otelWrapper struct {
+	otelRT http.RoundTripper
+	baseRT http.RoundTripper
+}
+
+// NewOtelRoundTripper returns an otelhttp-wrapped round tripper that implements
+// WrappedRoundTripper
+func NewOtelRoundTripper(rt http.RoundTripper) http.RoundTripper {
+	return &otelWrapper{otelRT: otelhttp.NewTransport(rt, otelhttp.WithPropagators(otel.NewCompositeTextMapPropagator(propagators.TraceContext{}, propagators.Baggage{}))), baseRT: rt}
+}
+
+func (o *otelWrapper) WrappedRoundTripper() http.RoundTripper { return o.baseRT }
+
+func (o *otelWrapper) RoundTrip(req *http.Request) (*http.Response, error) {
+	return o.otelRT.RoundTrip(req)
+}
+
 // DebugWrappers wraps a round tripper and logs based on the current log level.
 func DebugWrappers(rt http.RoundTripper) http.RoundTripper {
 	switch {

staging/src/k8s.io/client-go/transport/transport_test.go

@@ -23,6 +23,8 @@ import (
 	"fmt"
 	"net/http"
 	"testing"
+
+	"k8s.io/apimachinery/pkg/util/net"
 )
 
 const (
@@ -260,6 +262,8 @@ func TestNew(t *testing.T) {
 			if testCase.Err {
 				return
 			}
+			transport := transportFor(t, rt)
+			rt = transport
 
 			switch {
 			case testCase.Default && rt != http.DefaultTransport:
@@ -268,8 +272,6 @@ func TestNew(t *testing.T) {
 				t.Fatalf("got %#v, expected non-default transport", rt)
 			}
 
-			// We only know how to check TLSConfig on http.Transports
-			transport := rt.(*http.Transport)
 			switch {
 			case testCase.TLS && transport.TLSClientConfig == nil:
 				t.Fatalf("got %#v, expected TLSClientConfig", transport)
@@ -450,3 +452,17 @@ func Test_contextCanceller_RoundTrip(t *testing.T) {
 		})
 	}
 }
+
+// transportFor finds the underlying *http.Transport for the round tripper.
+// we only know how to check TLSConfig on http.Transports
+func transportFor(t *testing.T, rt http.RoundTripper) *http.Transport {
+	switch transport := rt.(type) {
+	case *http.Transport:
+		return transport
+	case net.RoundTripperWrapper:
+		return transportFor(t, transport.WrappedRoundTripper())
+	default:
+		t.Fatalf("unexpected transport type: %v", transport)
+		return nil
+	}
+}