Unify ComponentKubelet and add unit tests.

Author: zhifei92

cmd/kubelet/app/server.go

@@ -132,14 +132,9 @@ func init() {
 	otel.SetMeterProvider(noop.NewMeterProvider())
 }
 
-const (
-	// Kubelet component name
-	componentKubelet = "kubelet"
-)
-
 // NewKubeletCommand creates a *cobra.Command object with default parameters
 func NewKubeletCommand() *cobra.Command {
-	cleanFlagSet := pflag.NewFlagSet(componentKubelet, pflag.ContinueOnError)
+	cleanFlagSet := pflag.NewFlagSet(server.ComponentKubelet, pflag.ContinueOnError)
 	cleanFlagSet.SetNormalizeFunc(cliflag.WordSepNormalizeFunc)
 	kubeletFlags := options.NewKubeletFlags()
 
@@ -151,7 +146,7 @@ func NewKubeletCommand() *cobra.Command {
 	}
 
 	cmd := &cobra.Command{
-		Use: componentKubelet,
+		Use: server.ComponentKubelet,
 		Long: `The kubelet is the primary "node agent" that runs on each
 node. It can register the node with the apiserver using one of: the hostname; a flag to
 override the hostname; or specific logic for a cloud provider.
@@ -562,7 +557,7 @@ func makeEventRecorder(ctx context.Context, kubeDeps *kubelet.Dependencies, node
 		return
 	}
 	eventBroadcaster := record.NewBroadcaster(record.WithContext(ctx))
-	kubeDeps.Recorder = eventBroadcaster.NewRecorder(legacyscheme.Scheme, v1.EventSource{Component: componentKubelet, Host: string(nodeName)})
+	kubeDeps.Recorder = eventBroadcaster.NewRecorder(legacyscheme.Scheme, v1.EventSource{Component: server.ComponentKubelet, Host: string(nodeName)})
 	eventBroadcaster.StartStructuredLogging(3)
 	if kubeDeps.EventClient != nil {
 		klog.V(4).InfoS("Sending events to api server")
@@ -1386,7 +1381,7 @@ func newTracerProvider(s *options.KubeletServer) (oteltrace.TracerProvider, erro
 	}
 	resourceOpts := []otelsdkresource.Option{
 		otelsdkresource.WithAttributes(
-			semconv.ServiceNameKey.String(componentKubelet),
+			semconv.ServiceNameKey.String(server.ComponentKubelet),
 			semconv.HostNameKey.String(hostname),
 		),
 	}

pkg/kubelet/server/server.go

@@ -107,8 +107,11 @@ const (
 	debugFlagPath       = "/debug/flags/v"
 	podsPath            = "/pods"
 	runningPodsPath     = "/runningpods/"
+)
 
-	kubeletComponent = "kubelet"
+const (
+	// Kubelet component name
+	ComponentKubelet = "kubelet"
 )
 
 // Server is a http.Handler which exposes kubelet functionality over HTTP.
@@ -411,7 +414,8 @@ func (s *Server) InstallDefaultHandlers() {
 	healthz.InstallHandler(s.restfulCont, checkers...)
 
 	if utilfeature.DefaultFeatureGate.Enabled(zpagesfeatures.ComponentStatusz) {
-		statusz.Install(s.restfulCont, kubeletComponent, statusz.NewRegistry())
+		s.addMetricsBucketMatcher("statusz")
+		statusz.Install(s.restfulCont, ComponentKubelet, statusz.NewRegistry())
 	}
 
 	slis.SLIMetricsWithReset{}.Install(s.restfulCont)

pkg/kubelet/server/server_test.go

@@ -57,6 +57,7 @@ import (
 	"k8s.io/apiserver/pkg/server/healthz"
 	utilfeature "k8s.io/apiserver/pkg/util/feature"
 	featuregatetesting "k8s.io/component-base/featuregate/testing"
+	zpagesfeatures "k8s.io/component-base/zpages/features"
 	"k8s.io/kubelet/pkg/cri/streaming"
 	"k8s.io/kubelet/pkg/cri/streaming/portforward"
 	remotecommandserver "k8s.io/kubelet/pkg/cri/streaming/remotecommand"
@@ -1648,9 +1649,11 @@ func TestMetricBuckets(t *testing.T) {
 		"runningpods":                     {url: "/runningpods/", bucket: "runningpods"},
 		"stats":                           {url: "/stats/", bucket: "stats"},
 		"stats summary sub":               {url: "/stats/summary", bucket: "stats"},
+		"statusz":                         {url: "/statusz", bucket: "statusz"},
 		"invalid path":                    {url: "/junk", bucket: "other"},
 		"invalid path starting with good": {url: "/healthzjunk", bucket: "other"},
 	}
+	featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, zpagesfeatures.ComponentStatusz, true)
 	fw := newServerTest()
 	defer fw.testHTTPServer.Close()