kubeadm: Move IPv6DualStack feature gate to component config

kubeadm is setting the IPv6DualStack feature gate in the command line of the kubelet.
However, the kubelet is gradually moving away from command line flags towards component config use.
Hence, we should set the IPv6DualStack feature gate in the component config instead.

Signed-off-by: Rostislav M. Georgiev <[email protected]>

Author: rosti

cmd/kubeadm/app/componentconfigs/kubelet.go

@@ -105,6 +105,12 @@ func (kc *kubeletConfig) Default(cfg *kubeadmapi.ClusterConfiguration, _ *kubead
 		kc.config.FeatureGates = map[string]bool{}
 	}
 
+	// TODO: The following code should be removed after dual-stack is GA.
+	// Note: The user still retains the ability to explicitly set feature-gates and that value will overwrite this base value.
+	if enabled, present := cfg.FeatureGates[features.IPv6DualStack]; present {
+		kc.config.FeatureGates[features.IPv6DualStack] = enabled
+	}
+
 	if kc.config.StaticPodPath == "" {
 		kc.config.StaticPodPath = kubeadmapiv1beta2.DefaultManifestsDir
 	} else if kc.config.StaticPodPath != kubeadmapiv1beta2.DefaultManifestsDir {

cmd/kubeadm/app/componentconfigs/kubelet_test.go

@@ -229,7 +229,45 @@ func TestKubeletDefault(t *testing.T) {
 			},
 		},
 		{
-			name: "Service subnet, dual stack defaulting works",
+			name: "Service subnet, explicitly disabled dual stack defaulting works",
+			clusterCfg: kubeadmapi.ClusterConfiguration{
+				FeatureGates: map[string]bool{
+					features.IPv6DualStack: false,
+				},
+				Networking: kubeadmapi.Networking{
+					ServiceSubnet: "192.168.0.0/16",
+				},
+			},
+			expected: kubeletConfig{
+				config: kubeletconfig.KubeletConfiguration{
+					FeatureGates: map[string]bool{
+						features.IPv6DualStack: false,
+					},
+					StaticPodPath: kubeadmapiv1beta2.DefaultManifestsDir,
+					ClusterDNS:    []string{"192.168.0.10"},
+					Authentication: kubeletconfig.KubeletAuthentication{
+						X509: kubeletconfig.KubeletX509Authentication{
+							ClientCAFile: constants.CACertName,
+						},
+						Anonymous: kubeletconfig.KubeletAnonymousAuthentication{
+							Enabled: utilpointer.BoolPtr(kubeletAuthenticationAnonymousEnabled),
+						},
+						Webhook: kubeletconfig.KubeletWebhookAuthentication{
+							Enabled: utilpointer.BoolPtr(kubeletAuthenticationWebhookEnabled),
+						},
+					},
+					Authorization: kubeletconfig.KubeletAuthorization{
+						Mode: kubeletconfig.KubeletAuthorizationModeWebhook,
+					},
+					HealthzBindAddress: kubeletHealthzBindAddress,
+					HealthzPort:        utilpointer.Int32Ptr(constants.KubeletHealthzPort),
+					RotateCertificates: kubeletRotateCertificates,
+					ResolverConfig:     resolverConfig,
+				},
+			},
+		},
+		{
+			name: "Service subnet, enabled dual stack defaulting works",
 			clusterCfg: kubeadmapi.ClusterConfiguration{
 				FeatureGates: map[string]bool{
 					features.IPv6DualStack: true,
@@ -240,7 +278,9 @@ func TestKubeletDefault(t *testing.T) {
 			},
 			expected: kubeletConfig{
 				config: kubeletconfig.KubeletConfiguration{
-					FeatureGates:  map[string]bool{},
+					FeatureGates: map[string]bool{
+						features.IPv6DualStack: true,
+					},
 					StaticPodPath: kubeadmapiv1beta2.DefaultManifestsDir,
 					ClusterDNS:    []string{"192.168.0.10"},
 					Authentication: kubeletconfig.KubeletAuthentication{

cmd/kubeadm/app/phases/kubelet/BUILD

@@ -14,7 +14,6 @@ go_library(
         "//cmd/kubeadm/app/apis/kubeadm:go_default_library",
         "//cmd/kubeadm/app/componentconfigs:go_default_library",
         "//cmd/kubeadm/app/constants:go_default_library",
-        "//cmd/kubeadm/app/features:go_default_library",
         "//cmd/kubeadm/app/images:go_default_library",
         "//cmd/kubeadm/app/util:go_default_library",
         "//cmd/kubeadm/app/util/apiclient:go_default_library",

cmd/kubeadm/app/phases/kubelet/flags.go

@@ -28,14 +28,12 @@ import (
 
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
-	"k8s.io/kubernetes/cmd/kubeadm/app/features"
 	"k8s.io/kubernetes/cmd/kubeadm/app/images"
 	kubeadmutil "k8s.io/kubernetes/cmd/kubeadm/app/util"
 )
 
 type kubeletFlagsOpts struct {
 	nodeRegOpts              *kubeadmapi.NodeRegistrationOptions
-	featureGates             map[string]bool
 	pauseImage               string
 	registerTaintsUsingFlags bool
 }
@@ -63,7 +61,6 @@ func GetNodeNameAndHostname(cfg *kubeadmapi.NodeRegistrationOptions) (string, st
 func WriteKubeletDynamicEnvFile(cfg *kubeadmapi.ClusterConfiguration, nodeReg *kubeadmapi.NodeRegistrationOptions, registerTaintsUsingFlags bool, kubeletDir string) error {
 	flagOpts := kubeletFlagsOpts{
 		nodeRegOpts:              nodeReg,
-		featureGates:             cfg.FeatureGates,
 		pauseImage:               images.GetPauseImage(cfg),
 		registerTaintsUsingFlags: registerTaintsUsingFlags,
 	}
@@ -109,12 +106,6 @@ func buildKubeletArgMapCommon(opts kubeletFlagsOpts) map[string]string {
 		kubeletFlags["hostname-override"] = nodeName
 	}
 
-	// TODO: The following code should be removed after dual-stack is GA.
-	// Note: The user still retains the ability to explicitly set feature-gates and that value will overwrite this base value.
-	if enabled, present := opts.featureGates[features.IPv6DualStack]; present {
-		kubeletFlags["feature-gates"] = fmt.Sprintf("%s=%t", features.IPv6DualStack, enabled)
-	}
-
 	return kubeletFlags
 }