Kubeadm FG for dual-stack was introduced in #80145. This PR

progagates the kubeadm FG to the individual k8scomponents
on the control-plane node.

* Note: Users who want to join worker nodes to the cluster
will have to specify the dual-stack FG to kubelet using the
nodeRegistration.kubeletExtraArgs option as part of their
join config. Alternatively, they can use KUBELET_EXTRA_ARGS.

kubeadm FG: kubernetes/kubeadm#1612

cmd/kubeadm/app/componentconfigs/BUILD

@@ -15,6 +15,7 @@ go_library(
         "//cmd/kubeadm/app/apis/kubeadm:go_default_library",
         "//cmd/kubeadm/app/apis/kubeadm/v1beta2:go_default_library",
         "//cmd/kubeadm/app/constants:go_default_library",
+        "//cmd/kubeadm/app/features:go_default_library",
         "//cmd/kubeadm/app/util:go_default_library",
         "//cmd/kubeadm/app/util/apiclient:go_default_library",
         "//pkg/kubelet/apis/config:go_default_library",

cmd/kubeadm/app/componentconfigs/defaults.go

@@ -24,6 +24,7 @@ import (
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	kubeadmapiv1beta2 "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1beta2"
 	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
+	"k8s.io/kubernetes/cmd/kubeadm/app/features"
 	kubeletconfig "k8s.io/kubernetes/pkg/kubelet/apis/config"
 	kubeproxyconfig "k8s.io/kubernetes/pkg/proxy/apis/config"
 	utilpointer "k8s.io/utils/pointer"
@@ -51,6 +52,12 @@ func DefaultKubeProxyConfiguration(internalcfg *kubeadmapi.ClusterConfiguration)
 		externalproxycfg.ClientConnection.Kubeconfig = KubeproxyKubeConfigFileName
 	}
 
+	// TODO: The following code should be remvoved 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 := internalcfg.FeatureGates[features.IPv6DualStack]; present {
+		externalproxycfg.FeatureGates[features.IPv6DualStack] = enabled
+	}
+
 	// Run the rest of the kube-proxy defaulting code
 	Scheme.Default(externalproxycfg)
 

cmd/kubeadm/app/phases/controlplane/BUILD

@@ -34,6 +34,7 @@ go_library(
     deps = [
         "//cmd/kubeadm/app/apis/kubeadm: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/phases/certs:go_default_library",
         "//cmd/kubeadm/app/util:go_default_library",

cmd/kubeadm/app/phases/controlplane/manifests.go

@@ -30,6 +30,7 @@ import (
 	"k8s.io/klog"
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	kubeadmconstants "k8s.io/kubernetes/cmd/kubeadm/app/constants"
+	"k8s.io/kubernetes/cmd/kubeadm/app/features"
 	"k8s.io/kubernetes/cmd/kubeadm/app/images"
 	certphase "k8s.io/kubernetes/cmd/kubeadm/app/phases/certs"
 	kubeadmutil "k8s.io/kubernetes/cmd/kubeadm/app/util"
@@ -184,6 +185,12 @@ func getAPIServerCommand(cfg *kubeadmapi.ClusterConfiguration, localAPIEndpoint
 		}
 	}
 
+	// TODO: The following code should be remvoved 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 {
+		defaultArguments["feature-gates"] = fmt.Sprintf("%s=%t", features.IPv6DualStack, enabled)
+	}
+
 	if cfg.APIServer.ExtraArgs == nil {
 		cfg.APIServer.ExtraArgs = map[string]string{}
 	}
@@ -295,6 +302,12 @@ func getControllerManagerCommand(cfg *kubeadmapi.ClusterConfiguration) []string
 		}
 	}
 
+	// TODO: The following code should be remvoved 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 {
+		defaultArguments["feature-gates"] = fmt.Sprintf("%s=%t", features.IPv6DualStack, enabled)
+	}
+
 	command := []string{"kube-controller-manager"}
 	command = append(command, kubeadmutil.BuildArgumentListFromMap(defaultArguments, cfg.ControllerManager.ExtraArgs)...)
 
@@ -309,6 +322,12 @@ func getSchedulerCommand(cfg *kubeadmapi.ClusterConfiguration) []string {
 		"kubeconfig":   filepath.Join(kubeadmconstants.KubernetesDir, kubeadmconstants.SchedulerKubeConfigFileName),
 	}
 
+	// TODO: The following code should be remvoved 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 {
+		defaultArguments["feature-gates"] = fmt.Sprintf("%s=%t", features.IPv6DualStack, enabled)
+	}
+
 	command := []string{"kube-scheduler"}
 	command = append(command, kubeadmutil.BuildArgumentListFromMap(defaultArguments, cfg.Scheduler.ExtraArgs)...)
 	return command

cmd/kubeadm/app/phases/kubelet/BUILD

@@ -14,6 +14,7 @@ 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

@@ -27,6 +27,7 @@ import (
 	"k8s.io/klog"
 	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"
 	"k8s.io/kubernetes/cmd/kubeadm/app/util/initsystem"
@@ -120,6 +121,12 @@ func buildKubeletArgMap(opts kubeletFlagsOpts) map[string]string {
 
 	// TODO: Conditionally set `--cgroup-driver` to either `systemd` or `cgroupfs` for CRI other than Docker
 
+	// TODO: The following code should be remvoved 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
 }