Merge pull request #57962 from xiangpengzhao/proxy-feature-gates

Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

 Migrate FeatureGates type of kube-proxy from string to map[string]bool

**What this PR does / why we need it**:
Migration of FeatureGates type. This is a follow-up of #53025.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
ref: #53025
https://github.com/kubernetes/kubernetes/pull/57754#discussion_r160023416

**Special notes for your reviewer**:
/cc @luxas @mtaufen @ncdc 

**Release note**:

```release-note
action required: kube-proxy: feature gates are now specified as a map when provided via a JSON or YAML KubeProxyConfiguration, rather than as a string of key-value pairs.
```

cmd/kube-proxy/app/BUILD

@@ -92,6 +92,7 @@ go_library(
         "//vendor/k8s.io/apimachinery/pkg/util/wait:go_default_library",
         "//vendor/k8s.io/apiserver/pkg/server/healthz:go_default_library",
         "//vendor/k8s.io/apiserver/pkg/util/feature:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/util/flag:go_default_library",
         "//vendor/k8s.io/client-go/kubernetes:go_default_library",
         "//vendor/k8s.io/client-go/kubernetes/typed/core/v1:go_default_library",
         "//vendor/k8s.io/client-go/rest:go_default_library",
@@ -187,6 +188,7 @@ go_test(
     embed = [":go_default_library"],
     deps = [
         "//pkg/apis/core:go_default_library",
+        "//pkg/features:go_default_library",
         "//pkg/proxy/apis/kubeproxyconfig:go_default_library",
         "//pkg/proxy/ipvs:go_default_library",
         "//pkg/util/configz:go_default_library",

cmd/kube-proxy/app/server.go

@@ -39,6 +39,7 @@ import (
 	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/apiserver/pkg/server/healthz"
 	utilfeature "k8s.io/apiserver/pkg/util/feature"
+	"k8s.io/apiserver/pkg/util/flag"
 	clientgoclientset "k8s.io/client-go/kubernetes"
 	v1core "k8s.io/client-go/kubernetes/typed/core/v1"
 	"k8s.io/client-go/rest"
@@ -167,7 +168,8 @@ func AddFlags(options *Options, fs *pflag.FlagSet) {
 		"NAT timeout for TCP connections in the CLOSE_WAIT state")
 	fs.BoolVar(&options.config.EnableProfiling, "profiling", options.config.EnableProfiling, "If true enables profiling via web interface on /debug/pprof handler.")
 	fs.StringVar(&options.config.IPVS.Scheduler, "ipvs-scheduler", options.config.IPVS.Scheduler, "The ipvs scheduler type when proxy mode is ipvs")
-	utilfeature.DefaultFeatureGate.AddFlag(fs)
+	fs.Var(flag.NewMapStringBool(&options.config.FeatureGates), "feature-gates", "A set of key=value pairs that describe feature gates for alpha/experimental features. "+
+		"Options are:\n"+strings.Join(utilfeature.DefaultFeatureGate.KnownFeatures(), "\n"))
 }
 
 func NewOptions() *Options {
@@ -193,11 +195,14 @@ func (o *Options) Complete() error {
 			return err
 		} else {
 			o.config = c
-			// Make sure we apply the feature gate settings in the config file.
-			utilfeature.DefaultFeatureGate.Set(o.config.FeatureGates)
 		}
 	}
 
+	err := utilfeature.DefaultFeatureGate.SetFromMap(o.config.FeatureGates)
+	if err != nil {
+		return err
+	}
+
 	return nil
 }
 

cmd/kube-proxy/app/server_test.go

@@ -30,6 +30,7 @@ import (
 	"k8s.io/apimachinery/pkg/util/diff"
 	utilfeature "k8s.io/apiserver/pkg/util/feature"
 	api "k8s.io/kubernetes/pkg/apis/core"
+	"k8s.io/kubernetes/pkg/features"
 	"k8s.io/kubernetes/pkg/proxy/apis/kubeproxyconfig"
 	"k8s.io/kubernetes/pkg/proxy/ipvs"
 	"k8s.io/kubernetes/pkg/util/configz"
@@ -413,7 +414,8 @@ conntrack:
   min: 1
   tcpCloseWaitTimeout: 10s
   tcpEstablishedTimeout: 20s
-featureGates: "all"
+featureGates:
+  SupportIPVSProxyMode: true
 healthzBindAddress: "%s"
 hostnameOverride: "foo"
 iptables:
@@ -524,7 +526,7 @@ udpIdleTimeout: 123ms
 				TCPCloseWaitTimeout:   &metav1.Duration{Duration: 10 * time.Second},
 				TCPEstablishedTimeout: &metav1.Duration{Duration: 20 * time.Second},
 			},
-			FeatureGates:       "all",
+			FeatureGates:       map[string]bool{string(features.SupportIPVSProxyMode): true},
 			HealthzBindAddress: tc.healthzBindAddress,
 			HostnameOverride:   "foo",
 			IPTables: kubeproxyconfig.KubeProxyIPTablesConfiguration{