kubeadm: drop older etcd versions from kubeadm support

- drop versions < 1.22 in the etcd map
- use 3.5.9-0 for >= 1.22 versions
- make the minimum version for external etcd 3.4.13-4 and max 3.5.9-0
- update images_test to not rely on a pinned etcd version in tests

note: the image 3.4.18-0 was never released in registry.k8s.io!

cmd/kubeadm/app/constants/constants.go

@@ -306,7 +306,7 @@ const (
 	KubeletHealthzPort = 10248
 
 	// MinExternalEtcdVersion indicates minimum external etcd version which kubeadm supports
-	MinExternalEtcdVersion = "3.4.3-0"
+	MinExternalEtcdVersion = "3.4.13-4"
 
 	// DefaultEtcdVersion indicates the default etcd version that kubeadm uses
 	DefaultEtcdVersion = "3.5.9-0"
@@ -467,17 +467,12 @@ var (
 
 	// SupportedEtcdVersion lists officially supported etcd versions with corresponding Kubernetes releases
 	SupportedEtcdVersion = map[uint8]string{
-		17: "3.4.3-0",
-		18: "3.4.3-0",
-		19: "3.4.18-0",
-		20: "3.4.18-0",
-		21: "3.4.18-0",
-		22: "3.5.8-0",
-		23: "3.5.8-0",
-		24: "3.5.8-0",
-		25: "3.5.8-0",
-		26: "3.5.8-0",
-		27: "3.5.8-0",
+		22: "3.5.9-0",
+		23: "3.5.9-0",
+		24: "3.5.9-0",
+		25: "3.5.9-0",
+		26: "3.5.9-0",
+		27: "3.5.9-0",
 		28: "3.5.9-0",
 	}
 

cmd/kubeadm/app/images/images_test.go

@@ -27,8 +27,8 @@ import (
 )
 
 const (
-	testversion = "v10.1.2-alpha.1.100+0123456789abcdef+SOMETHING"
-	expected    = "v10.1.2-alpha.1.100_0123456789abcdef_SOMETHING"
+	testversion = "v10.1.2-alpha.1.100+0123456789abcdef"
+	expected    = "v10.1.2-alpha.1.100_0123456789abcdef"
 	gcrPrefix   = "registry.k8s.io"
 )
 
@@ -97,24 +97,25 @@ func TestGetKubernetesImage(t *testing.T) {
 }
 
 func TestGetEtcdImage(t *testing.T) {
+	testEtcdVer, _, _ := constants.EtcdSupportedVersion(constants.SupportedEtcdVersion, testversion)
 	var tests = []struct {
 		expected string
 		cfg      *kubeadmapi.ClusterConfiguration
 	}{
 		{
 			cfg: &kubeadmapi.ClusterConfiguration{
 				ImageRepository:   "real.repo",
-				KubernetesVersion: "1.18.0",
+				KubernetesVersion: testversion,
 				Etcd: kubeadmapi.Etcd{
 					Local: &kubeadmapi.LocalEtcd{},
 				},
 			},
-			expected: "real.repo/etcd:3.4.3-0",
+			expected: "real.repo/etcd:" + testEtcdVer.String(),
 		},
 		{
 			cfg: &kubeadmapi.ClusterConfiguration{
 				ImageRepository:   "real.repo",
-				KubernetesVersion: "1.18.0",
+				KubernetesVersion: testversion,
 				Etcd: kubeadmapi.Etcd{
 					Local: &kubeadmapi.LocalEtcd{
 						ImageMeta: kubeadmapi.ImageMeta{
@@ -128,7 +129,7 @@ func TestGetEtcdImage(t *testing.T) {
 		{
 			cfg: &kubeadmapi.ClusterConfiguration{
 				ImageRepository:   "real.repo",
-				KubernetesVersion: "1.18.0",
+				KubernetesVersion: testversion,
 				Etcd: kubeadmapi.Etcd{
 					Local: &kubeadmapi.LocalEtcd{
 						ImageMeta: kubeadmapi.ImageMeta{
@@ -137,7 +138,7 @@ func TestGetEtcdImage(t *testing.T) {
 					},
 				},
 			},
-			expected: "override/etcd:3.4.3-0",
+			expected: "override/etcd:" + testEtcdVer.String(),
 		},
 		{
 			expected: GetGenericImage(gcrPrefix, "etcd", constants.DefaultEtcdVersion),