Merge pull request #128985 from yongruilin/flagz-kube-proxy

feat: Add flagz endpoint for kube-proxy

cmd/kube-proxy/app/options.go

@@ -31,6 +31,8 @@ import (
 	utilfeature "k8s.io/apiserver/pkg/util/feature"
 	cliflag "k8s.io/component-base/cli/flag"
 	logsapi "k8s.io/component-base/logs/api/v1"
+	zpagesfeatures "k8s.io/component-base/zpages/features"
+	"k8s.io/component-base/zpages/flagz"
 	"k8s.io/klog/v2"
 	"k8s.io/kube-proxy/config/v1alpha1"
 	"k8s.io/kubernetes/pkg/cluster/ports"
@@ -63,6 +65,8 @@ type Options struct {
 	proxyServer proxyRun
 	// errCh is the channel that errors will be sent
 	errCh chan error
+	// flagz is the Reader interface to get flags for the flagz page.
+	flagz flagz.Reader
 
 	// The fields below here are placeholders for flags that can't be directly mapped into
 	// config.KubeProxyConfiguration.
@@ -233,7 +237,21 @@ func (o *Options) Complete(fs *pflag.FlagSet) error {
 		return err
 	}
 
-	return utilfeature.DefaultMutableFeatureGate.SetFromMap(o.config.FeatureGates)
+	if err := utilfeature.DefaultMutableFeatureGate.SetFromMap(o.config.FeatureGates); err != nil {
+		return err
+	}
+
+	if utilfeature.DefaultFeatureGate.Enabled(zpagesfeatures.ComponentFlagz) {
+		nfs := cliflag.NamedFlagSets{
+			FlagSets: make(map[string]*pflag.FlagSet),
+		}
+		nfs.FlagSets["generic"] = fs
+		o.flagz = flagz.NamedFlagSetsReader{
+			FlagSets: nfs,
+		}
+	}
+
+	return nil
 }
 
 // copyLogsFromFlags applies the logging flags from the given flag set to the given
@@ -353,7 +371,7 @@ func (o *Options) Run(ctx context.Context) error {
 	// We ignore err otherwise; the cleanup is best-effort, and the backends will have
 	// logged messages if they failed in interesting ways.
 
-	proxyServer, err := newProxyServer(ctx, o.config, o.master, o.InitAndExit)
+	proxyServer, err := newProxyServer(ctx, o.config, o.master, o.InitAndExit, o.flagz)
 	if err != nil {
 		return err
 	}

cmd/kube-proxy/app/server.go

@@ -60,6 +60,7 @@ import (
 	"k8s.io/component-base/metrics/prometheus/slis"
 	"k8s.io/component-base/version"
 	"k8s.io/component-base/version/verflag"
+	"k8s.io/component-base/zpages/flagz"
 	nodeutil "k8s.io/component-helpers/node/util"
 	"k8s.io/klog/v2"
 	api "k8s.io/kubernetes/pkg/apis/core"
@@ -162,6 +163,7 @@ type ProxyServer struct {
 	Hostname        string
 	PrimaryIPFamily v1.IPFamily
 	NodeIPs         map[v1.IPFamily]net.IP
+	flagz           flagz.Reader
 
 	podCIDRs []string // only used for LocalModeNodeCIDR
 
@@ -169,11 +171,12 @@ type ProxyServer struct {
 }
 
 // newProxyServer creates a ProxyServer based on the given config
-func newProxyServer(ctx context.Context, config *kubeproxyconfig.KubeProxyConfiguration, master string, initOnly bool) (*ProxyServer, error) {
+func newProxyServer(ctx context.Context, config *kubeproxyconfig.KubeProxyConfiguration, master string, initOnly bool, flagzReader flagz.Reader) (*ProxyServer, error) {
 	logger := klog.FromContext(ctx)
 
 	s := &ProxyServer{
 		Config: config,
+		flagz:  flagzReader,
 	}
 
 	cz, err := configz.New(kubeproxyconfig.GroupName)
@@ -435,7 +438,7 @@ func serveHealthz(ctx context.Context, hz *healthcheck.ProxierHealthServer, errC
 	go wait.Until(fn, 5*time.Second, ctx.Done())
 }
 
-func serveMetrics(ctx context.Context, bindAddress string, proxyMode kubeproxyconfig.ProxyMode, enableProfiling bool, errCh chan error) {
+func serveMetrics(ctx context.Context, bindAddress string, proxyMode kubeproxyconfig.ProxyMode, enableProfiling bool, flagzReader flagz.Reader, errCh chan error) {
 	if len(bindAddress) == 0 {
 		return
 	}
@@ -459,6 +462,10 @@ func serveMetrics(ctx context.Context, bindAddress string, proxyMode kubeproxyco
 
 	configz.InstallHandler(proxyMux)
 
+	if flagzReader != nil {
+		flagz.Install(proxyMux, "kube-proxy", flagzReader)
+	}
+
 	fn := func() {
 		var err error
 		defer func() {
@@ -526,7 +533,7 @@ func (s *ProxyServer) Run(ctx context.Context) error {
 	serveHealthz(ctx, s.HealthzServer, healthzErrCh)
 
 	// Start up a metrics server if requested
-	serveMetrics(ctx, s.Config.MetricsBindAddress, s.Config.Mode, s.Config.EnableProfiling, metricsErrCh)
+	serveMetrics(ctx, s.Config.MetricsBindAddress, s.Config.Mode, s.Config.EnableProfiling, s.flagz, metricsErrCh)
 
 	noProxyName, err := labels.NewRequirement(apis.LabelServiceProxyName, selection.DoesNotExist, nil)
 	if err != nil {