Add validation of apiserver-advertise-address

cmd/kubeadm/app/cmd/phases/addons.go

@@ -144,7 +144,7 @@ func getAddonsSubCommands() []*cobra.Command {
 		cmd.Flags().StringVar(&cfg.ImageRepository, "image-repository", cfg.ImageRepository, `Choose a container registry to pull control plane images from`)
 
 		if properties.use == "all" || properties.use == "kube-proxy" {
-			cmd.Flags().StringVar(&cfg.API.AdvertiseAddress, "apiserver-advertise-address", cfg.API.AdvertiseAddress, `The IP address or DNS name the API server is accessible on`)
+			cmd.Flags().StringVar(&cfg.API.AdvertiseAddress, "apiserver-advertise-address", cfg.API.AdvertiseAddress, `The IP address the API server is accessible on`)
 			cmd.Flags().Int32Var(&cfg.API.BindPort, "apiserver-bind-port", cfg.API.BindPort, `The port the API server is accessible on`)
 			cmd.Flags().StringVar(&cfg.Networking.PodSubnet, "pod-network-cidr", cfg.Networking.PodSubnet, `The range of IP addresses used for the Pod network`)
 		}

cmd/kubeadm/app/util/config/masterconfig.go

@@ -37,9 +37,14 @@ import (
 // SetInitDynamicDefaults checks and sets configuration values for Master node
 func SetInitDynamicDefaults(cfg *kubeadmapi.MasterConfiguration) error {
 
+	// validate cfg.API.AdvertiseAddress.
+	addressIP := net.ParseIP(cfg.API.AdvertiseAddress)
+	if addressIP == nil && cfg.API.AdvertiseAddress != "" {
+		return fmt.Errorf("couldn't use \"%s\" as \"apiserver-advertise-address\", must be ipv4 or ipv6 address", cfg.API.AdvertiseAddress)
+	}
 	// Choose the right address for the API Server to advertise. If the advertise address is localhost or 0.0.0.0, the default interface's IP address is used
 	// This is the same logic as the API Server uses
-	ip, err := netutil.ChooseBindAddress(net.ParseIP(cfg.API.AdvertiseAddress))
+	ip, err := netutil.ChooseBindAddress(addressIP)
 	if err != nil {
 		return err
 	}