Add etcd image version to kubeadm

Author: jpbetz

cmd/kubeadm/app/constants/constants.go

@@ -262,6 +262,10 @@ const (
 	// DefaultEtcdVersion indicates the default etcd version that kubeadm uses
 	DefaultEtcdVersion = "3.3.15"
 
+	// DefaultEtcdImageVersion indicates the etcd image version that kubeadm uses.
+	// For example, the image version of "k8s.gcr.io/etcd:3.3.15-0" is "0".
+	DefaultEtcdImageVersion = "0"
+
 	// PauseVersion indicates the default pause image version for kubeadm
 	PauseVersion = "3.1"
 
@@ -424,8 +428,8 @@ var (
 		13: "3.2.24",
 		14: "3.3.10",
 		15: "3.3.10",
-		16: "3.3.15",
-		17: "3.3.15",
+		16: "3.3.15-0",
+		17: "3.3.15-0",
 	}
 
 	// KubeadmCertsClusterRoleName sets the name for the ClusterRole that allows

cmd/kubeadm/app/images/images.go

@@ -68,7 +68,7 @@ func GetEtcdImage(cfg *kubeadmapi.ClusterConfiguration) string {
 		etcdImageRepository = cfg.Etcd.Local.ImageRepository
 	}
 	// Etcd uses an imageTag that corresponds to the etcd version matching the Kubernetes version
-	etcdImageTag := constants.DefaultEtcdVersion
+	etcdImageTag := fmt.Sprintf("%s-%s", constants.DefaultEtcdVersion, constants.DefaultEtcdImageVersion)
 	etcdVersion, err := constants.EtcdSupportedVersion(cfg.KubernetesVersion)
 	if err == nil {
 		etcdImageTag = etcdVersion.String()