Update kubeproxy config validation to support list of comma

separated pod CIDRs. Dual-stack feature must be enabled for the
validation to be done.

Author: Arvinderpal

cmd/kubeadm/app/componentconfigs/validation_test.go

@@ -196,7 +196,7 @@ func TestValidateKubeProxyConfiguration(t *testing.T) {
 					},
 				},
 			},
-			msg:       "must be a valid CIDR block (e.g. 10.100.0.0/16)",
+			msg:       "must be a valid CIDR block (e.g. 10.100.0.0/16 or FD02::0:0:0/96)",
 			expectErr: true,
 		},
 		{

pkg/proxy/apis/config/validation/BUILD

@@ -12,6 +12,7 @@ go_library(
     importpath = "k8s.io/kubernetes/pkg/proxy/apis/config/validation",
     deps = [
         "//pkg/apis/core/validation:go_default_library",
+        "//pkg/features:go_default_library",
         "//pkg/proxy/apis/config:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/net:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/sets:go_default_library",

pkg/proxy/apis/config/validation/validation.go

@@ -28,6 +28,7 @@ import (
 	"k8s.io/apimachinery/pkg/util/validation/field"
 	componentbaseconfig "k8s.io/component-base/config"
 	apivalidation "k8s.io/kubernetes/pkg/apis/core/validation"
+	kubefeatures "k8s.io/kubernetes/pkg/features"
 	kubeproxyconfig "k8s.io/kubernetes/pkg/proxy/apis/config"
 )
 
@@ -67,8 +68,17 @@ func Validate(config *kubeproxyconfig.KubeProxyConfiguration) field.ErrorList {
 	allErrs = append(allErrs, validateHostPort(config.MetricsBindAddress, newPath.Child("MetricsBindAddress"))...)
 
 	if config.ClusterCIDR != "" {
-		if _, _, err := net.ParseCIDR(config.ClusterCIDR); err != nil {
-			allErrs = append(allErrs, field.Invalid(newPath.Child("ClusterCIDR"), config.ClusterCIDR, "must be a valid CIDR block (e.g. 10.100.0.0/16)"))
+		if config.FeatureGates[string(kubefeatures.IPv6DualStack)] {
+			cidrs := strings.Split(config.ClusterCIDR, ",")
+			for _, cidr := range cidrs {
+				if _, _, err := net.ParseCIDR(cidr); err != nil {
+					allErrs = append(allErrs, field.Invalid(newPath.Child("ClusterCIDR"), cidr, "must be a valid CIDR block (e.g. 10.100.0.0/16 or FD02::0:0:0/96)"))
+				}
+			}
+		} else {
+			if _, _, err := net.ParseCIDR(config.ClusterCIDR); err != nil {
+				allErrs = append(allErrs, field.Invalid(newPath.Child("ClusterCIDR"), config.ClusterCIDR, "must be a valid CIDR block (e.g. 10.100.0.0/16 or FD02::0:0:0/96)"))
+			}
 		}
 	}
 

pkg/proxy/apis/config/validation/validation_test.go

@@ -202,7 +202,7 @@ func TestValidateKubeProxyConfiguration(t *testing.T) {
 					TCPCloseWaitTimeout:   &metav1.Duration{Duration: 5 * time.Second},
 				},
 			},
-			msg: "must be a valid CIDR block (e.g. 10.100.0.0/16)",
+			msg: "must be a valid CIDR block (e.g. 10.100.0.0/16 or FD02::0:0:0/96)",
 		},
 		{
 			config: kubeproxyconfig.KubeProxyConfiguration{