update default qps for webhook (open-cluster-management-io#141)

Signed-off-by: ldpliu <daliu@redhat.com>

pkg/cmd/webhook/webhook.go

@@ -5,39 +5,78 @@ import (
 
 	admissionserver "github.com/openshift/generic-admission-server/pkg/cmd/server"
 	"github.com/spf13/cobra"
+	"github.com/spf13/pflag"
 	genericapiserver "k8s.io/apiserver/pkg/server"
 	utilfeature "k8s.io/apiserver/pkg/util/feature"
 	"open-cluster-management.io/work/pkg/webhook"
 )
 
 func NewAdmissionHook() *cobra.Command {
-	o := admissionserver.NewAdmissionServerOptions(os.Stdout, os.Stderr, &webhook.ManifestWorkAdmissionHook{})
-
+	ops := NewOptions()
 	cmd := &cobra.Command{
 		Use:   "webhook",
 		Short: "Start Managed Cluster Admission Server",
 		RunE: func(c *cobra.Command, args []string) error {
 			stopCh := genericapiserver.SetupSignalHandler()
 
-			if err := o.Complete(); err != nil {
+			if err := ops.ServerOptions.Complete(); err != nil {
 				return err
 			}
-			if err := o.Validate(args); err != nil {
+			if err := ops.ServerOptions.Validate(args); err != nil {
 				return err
 			}
-			if err := o.RunAdmissionServer(stopCh); err != nil {
+			if err := ops.RunAdmissionServer(ops.ServerOptions, stopCh); err != nil {
 				return err
 			}
 			return nil
 		},
 	}
 
 	flags := cmd.Flags()
+	ops.AddFlags(flags)
+	return cmd
+}
+
+// Config contains the server (the webhook) cert and key.
+type Options struct {
+	QPS           float32
+	Burst         int
+	ServerOptions *admissionserver.AdmissionServerOptions
+}
+
+// NewOptions constructs a new set of default options for webhook.
+func NewOptions() *Options {
+	return &Options{
+		QPS:           100.0,
+		Burst:         200,
+		ServerOptions: admissionserver.NewAdmissionServerOptions(os.Stdout, os.Stderr, &webhook.ManifestWorkAdmissionHook{}),
+	}
+}
+
+func (c *Options) AddFlags(fs *pflag.FlagSet) {
+	fs.Float32Var(&c.QPS, "max-qps", c.QPS,
+		"Maximum QPS to the hub server from this webhook.")
+	fs.IntVar(&c.Burst, "max-burst", c.Burst,
+		"Maximum burst for throttle.")
+
 	featureGate := utilfeature.DefaultMutableFeatureGate
-	featureGate.AddFlag(flags)
-	o.RecommendedOptions.FeatureGate = featureGate
+	featureGate.AddFlag(fs)
 
-	o.RecommendedOptions.AddFlags(cmd.Flags())
+	c.ServerOptions.RecommendedOptions.FeatureGate = featureGate
+	c.ServerOptions.RecommendedOptions.AddFlags(fs)
+}
 
-	return cmd
+// change the default QPS and Butst, so rewrite this func
+func (c *Options) RunAdmissionServer(o *admissionserver.AdmissionServerOptions, stopCh <-chan struct{}) error {
+	config, err := o.Config()
+	if err != nil {
+		return err
+	}
+	config.RestConfig.QPS = c.QPS
+	config.RestConfig.Burst = c.Burst
+	server, err := config.Complete().New()
+	if err != nil {
+		return err
+	}
+	return server.GenericAPIServer.PrepareRun().Run(stopCh)
 }