experimental host user ns defaulting

pkg/util/config/feature_gate.go

@@ -43,18 +43,26 @@ const (
 	dynamicKubeletConfig      = "DynamicKubeletConfig"
 	dynamicVolumeProvisioning = "DynamicVolumeProvisioning"
 	streamingProxyRedirects   = "StreamingProxyRedirects"
+
+	// experimentalHostUserNamespaceDefaulting Default userns=host for containers
+	// that are using other host namespaces, host mounts, the pod contains a privileged container,
+	// or specific non-namespaced capabilities
+	// (MKNOD, SYS_MODULE, SYS_TIME). This should only be enabled if user namespace remapping is enabled
+	// in the docker daemon.
+	experimentalHostUserNamespaceDefaultingGate = "ExperimentalHostUserNamespaceDefaulting"
 )
 
 var (
 	// Default values for recorded features.  Every new feature gate should be
 	// represented here.
 	knownFeatures = map[string]featureSpec{
-		allAlphaGate:              {false, alpha},
-		externalTrafficLocalOnly:  {true, beta},
-		appArmor:                  {true, beta},
-		dynamicKubeletConfig:      {false, alpha},
-		dynamicVolumeProvisioning: {true, alpha},
-		streamingProxyRedirects:   {false, alpha},
+		allAlphaGate:                                {false, alpha},
+		externalTrafficLocalOnly:                    {true, beta},
+		appArmor:                                    {true, beta},
+		dynamicKubeletConfig:                        {false, alpha},
+		dynamicVolumeProvisioning:                   {true, alpha},
+		streamingProxyRedirects:                     {false, alpha},
+		experimentalHostUserNamespaceDefaultingGate: {false, alpha},
 	}
 
 	// Special handling for a few gates.
@@ -115,6 +123,10 @@ type FeatureGate interface {
 	// owner: timstclair
 	// alpha: v1.5
 	StreamingProxyRedirects() bool
+
+	// owner: @pweil-
+	// alpha: v1.5
+	ExperimentalHostUserNamespaceDefaulting() bool
 }
 
 // featureGate implements FeatureGate as well as pflag.Value for flag parsing.
@@ -209,6 +221,11 @@ func (f *featureGate) StreamingProxyRedirects() bool {
 	return f.lookup(streamingProxyRedirects)
 }
 
+// ExperimentalHostUserNamespaceDefaulting returns value for experimentalHostUserNamespaceDefaulting
+func (f *featureGate) ExperimentalHostUserNamespaceDefaulting() bool {
+	return f.lookup(experimentalHostUserNamespaceDefaultingGate)
+}
+
 func (f *featureGate) lookup(key string) bool {
 	defaultValue := f.known[key].enabled
 	if f.enabled != nil {