Support enabling alpha features with feature gates

This sets the feature gates on every kube-system component (apiserver,
kubelet, etc.)

Fixes kubernetes#896

cmd/localkube/cmd/options.go

@@ -65,6 +65,7 @@ func AddFlags(s *localkube.LocalkubeServer) {
 	flag.IPVar(&s.NodeIP, "node-ip", s.NodeIP, "IP address of the node. If set, kubelet will use this IP address for the node.")
 	flag.StringVar(&s.ContainerRuntime, "container-runtime", "", "The container runtime to be used")
 	flag.StringVar(&s.NetworkPlugin, "network-plugin", "", "The name of the network plugin")
+	flag.StringVar(&s.FeatureGates, "feature-gates", "", "A set of key=value pairs that describe feature gates for alpha/experimental features.")
 	flag.Var(&s.ExtraConfig, "extra-config", "A set of key=value pairs that describe configuration that may be passed to different components. The key should be '.' separated, and the first part before the dot is the component to apply the configuration to.")
 
 	// These two come from vendor/ packages that use flags. We should hide them

cmd/localkube/cmd/start.go

@@ -24,6 +24,7 @@ import (
 	"github.com/coreos/pkg/capnslog"
 	"k8s.io/kubernetes/pkg/capabilities"
 	"k8s.io/kubernetes/pkg/kubelet/types"
+	"k8s.io/kubernetes/pkg/util/config"
 	"k8s.io/minikube/pkg/localkube"
 	"k8s.io/minikube/pkg/version"
 )
@@ -65,6 +66,15 @@ func SetupServer(s *localkube.LocalkubeServer) {
 		}
 	}
 
+	//Set feature gates
+	fmt.Println("Feature gates:", s.FeatureGates)
+	if s.FeatureGates != "" {
+		err := config.DefaultFeatureGate.Set(s.FeatureGates)
+		if err != nil {
+			fmt.Printf("Error setting feature gates: %s")
+		}
+	}
+
 	// Setup capabilities. This can only be done once per binary.
 	allSources, _ := types.GetValidatedSources([]string{types.AllSource})
 	c := capabilities.Capabilities{

cmd/minikube/cmd/start.go

@@ -51,6 +51,7 @@ const (
 	hypervVirtualSwitch   = "hyperv-virtual-switch"
 	kvmNetwork            = "kvm-network"
 	keepContext           = "keep-context"
+	featureGates          = "feature-gates"
 )
 
 var (
@@ -110,6 +111,7 @@ func runStart(cmd *cobra.Command, args []string) {
 	kubernetesConfig := cluster.KubernetesConfig{
 		KubernetesVersion: viper.GetString(kubernetesVersion),
 		NodeIP:            ip,
+		FeatureGates:      viper.GetString(featureGates),
 		ContainerRuntime:  viper.GetString(containerRuntime),
 		NetworkPlugin:     viper.GetString(networkPlugin),
 		ExtraOptions:      extraOptions,
@@ -231,6 +233,7 @@ func init() {
 	startCmd.Flags().String(kubernetesVersion, constants.DefaultKubernetesVersion, "The kubernetes version that the minikube VM will use (ex: v1.2.3) \n OR a URI which contains a localkube binary (ex: https://storage.googleapis.com/minikube/k8sReleases/v1.3.0/localkube-linux-amd64)")
 	startCmd.Flags().String(containerRuntime, "", "The container runtime to be used")
 	startCmd.Flags().String(networkPlugin, "", "The name of the network plugin")
+	startCmd.Flags().String(featureGates, "", "A set of key=value pairs that describe feature gates for alpha/experimental features.")
 	startCmd.Flags().Var(&extraOptions, "extra-config",
 		`A set of key=value pairs that describe configuration that may be passed to different components.
 		The key should be '.' separated, and the first part before the dot is the component to apply the configuration to.

docs/bash-completion

@@ -817,6 +817,8 @@ _minikube_start()
     local_nonpersistent_flags+=("--docker-env=")
     flags+=("--extra-config=")
     local_nonpersistent_flags+=("--extra-config=")
+    flags+=("--feature-gates=")
+    local_nonpersistent_flags+=("--feature-gates=")
     flags+=("--host-only-cidr=")
     local_nonpersistent_flags+=("--host-only-cidr=")
     flags+=("--hyperv-virtual-switch=")

docs/minikube_start.md

@@ -22,6 +22,7 @@ minikube start
       --extra-config ExtraOption        A set of key=value pairs that describe configuration that may be passed to different components.
 		The key should be '.' separated, and the first part before the dot is the component to apply the configuration to.
 		Valid components are: kubelet, apiserver, controller-manager, etcd, proxy, scheduler.
+      --feature-gates string            A set of key=value pairs that describe feature gates for alpha/experimental features.
       --host-only-cidr string           The CIDR to be used for the minikube VM (only supported with Virtualbox driver) (default "192.168.99.1/24")
       --hyperv-virtual-switch string    The hyperv virtual switch name. Defaults to first found. (only supported with HyperV driver)
       --insecure-registry stringSlice   Insecure Docker registries to pass to the Docker daemon

pkg/localkube/localkube.go

@@ -56,6 +56,7 @@ type LocalkubeServer struct {
 	NodeIP                   net.IP
 	ContainerRuntime         string
 	NetworkPlugin            string
+	FeatureGates             string
 	ExtraConfig              util.ExtraOptionSlice
 }
 

pkg/minikube/cluster/cluster.go

@@ -199,6 +199,7 @@ type KubernetesConfig struct {
 	NodeIP            string
 	ContainerRuntime  string
 	NetworkPlugin     string
+	FeatureGates      string
 	ExtraOptions      util.ExtraOptionSlice
 }
 

pkg/minikube/cluster/commands.go

@@ -150,6 +150,10 @@ func GenLocalkubeStartCmd(kubernetesConfig KubernetesConfig) (string, error) {
 		flagVals = append(flagVals, "--network-plugin="+kubernetesConfig.NetworkPlugin)
 	}
 
+	if kubernetesConfig.FeatureGates != "" {
+		flagVals = append(flagVals, "--feature-gates="+kubernetesConfig.FeatureGates)
+	}
+
 	for _, e := range kubernetesConfig.ExtraOptions {
 		flagVals = append(flagVals, fmt.Sprintf("--extra-config=%s", e.String()))
 	}