kubeadm: only apply the new "control-plane" label during init/join

- Update the markcontrolplane phase used by init and join to
only label the nodes with the new control plane label.
- Cleanup TODOs about the old label.
- Remove outdated comment about selfhosting in staticpod/utils.go.
Selfhosting has not been supported in kubeadm for a while
and the comment also mentions the "master" label.
- Update unit tests.

cmd/kubeadm/app/phases/markcontrolplane/markcontrolplane.go

@@ -19,31 +19,23 @@ package markcontrolplane
 import (
 	"fmt"
 
-	"k8s.io/api/core/v1"
+	v1 "k8s.io/api/core/v1"
 	clientset "k8s.io/client-go/kubernetes"
 
 	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
 	"k8s.io/kubernetes/cmd/kubeadm/app/util/apiclient"
 )
 
+// labelsToAdd holds a list of labels that are applied on kubeadm managed control plane nodes
 var labelsToAdd = []string{
-	// TODO: remove this label:
-	// https://github.com/kubernetes/kubeadm/issues/2200
-	constants.LabelNodeRoleOldControlPlane,
 	constants.LabelNodeRoleControlPlane,
 	constants.LabelExcludeFromExternalLB,
 }
 
 // MarkControlPlane taints the control-plane and sets the control-plane label
 func MarkControlPlane(client clientset.Interface, controlPlaneName string, taints []v1.Taint) error {
-	// TODO: remove this "deprecated" amend and pass "labelsToAdd" directly:
-	// https://github.com/kubernetes/kubeadm/issues/2200
-	labels := make([]string, len(labelsToAdd))
-	copy(labels, labelsToAdd)
-	labels[0] = constants.LabelNodeRoleOldControlPlane + "(deprecated)"
-
 	fmt.Printf("[mark-control-plane] Marking the node %s as control-plane by adding the labels: %v\n",
-		controlPlaneName, labels)
+		controlPlaneName, labelsToAdd)
 
 	if len(taints) > 0 {
 		taintStrs := []string{}

cmd/kubeadm/app/phases/markcontrolplane/markcontrolplane_test.go

@@ -49,26 +49,25 @@ func TestMarkControlPlane(t *testing.T) {
 			existingLabels: []string{""},
 			existingTaints: nil,
 			newTaints:      []v1.Taint{kubeadmconstants.OldControlPlaneTaint},
-			expectedPatch:  `{"metadata":{"labels":{"node-role.kubernetes.io/control-plane":"","node-role.kubernetes.io/master":"","node.kubernetes.io/exclude-from-external-load-balancers":""}},"spec":{"taints":[{"effect":"NoSchedule","key":"node-role.kubernetes.io/master"}]}}`,
+			expectedPatch:  `{"metadata":{"labels":{"node-role.kubernetes.io/control-plane":"","node.kubernetes.io/exclude-from-external-load-balancers":""}},"spec":{"taints":[{"effect":"NoSchedule","key":"node-role.kubernetes.io/master"}]}}`,
 		},
 		{
 			name:           "control-plane label and taint missing but taint not wanted",
 			existingLabels: []string{""},
 			existingTaints: nil,
 			newTaints:      nil,
-			expectedPatch:  `{"metadata":{"labels":{"node-role.kubernetes.io/control-plane":"","node-role.kubernetes.io/master":"","node.kubernetes.io/exclude-from-external-load-balancers":""}}}`,
+			expectedPatch:  `{"metadata":{"labels":{"node-role.kubernetes.io/control-plane":"","node.kubernetes.io/exclude-from-external-load-balancers":""}}}`,
 		},
 		{
 			name:           "control-plane label missing",
 			existingLabels: []string{""},
 			existingTaints: []v1.Taint{kubeadmconstants.OldControlPlaneTaint},
 			newTaints:      []v1.Taint{kubeadmconstants.OldControlPlaneTaint},
-			expectedPatch:  `{"metadata":{"labels":{"node-role.kubernetes.io/control-plane":"","node-role.kubernetes.io/master":"","node.kubernetes.io/exclude-from-external-load-balancers":""}}}`,
+			expectedPatch:  `{"metadata":{"labels":{"node-role.kubernetes.io/control-plane":"","node.kubernetes.io/exclude-from-external-load-balancers":""}}}`,
 		},
 		{
 			name: "control-plane taint missing",
 			existingLabels: []string{
-				kubeadmconstants.LabelNodeRoleOldControlPlane,
 				kubeadmconstants.LabelNodeRoleControlPlane,
 				kubeadmconstants.LabelExcludeFromExternalLB,
 			},
@@ -79,7 +78,6 @@ func TestMarkControlPlane(t *testing.T) {
 		{
 			name: "nothing missing",
 			existingLabels: []string{
-				kubeadmconstants.LabelNodeRoleOldControlPlane,
 				kubeadmconstants.LabelNodeRoleControlPlane,
 				kubeadmconstants.LabelExcludeFromExternalLB,
 			},
@@ -90,7 +88,6 @@ func TestMarkControlPlane(t *testing.T) {
 		{
 			name: "has taint and no new taints wanted",
 			existingLabels: []string{
-				kubeadmconstants.LabelNodeRoleOldControlPlane,
 				kubeadmconstants.LabelNodeRoleControlPlane,
 				kubeadmconstants.LabelExcludeFromExternalLB,
 			},

cmd/kubeadm/app/util/staticpod/utils.go

@@ -288,13 +288,6 @@ func createHTTPProbe(host, path string, port int, scheme v1.URIScheme, initialDe
 
 // GetAPIServerProbeAddress returns the probe address for the API server
 func GetAPIServerProbeAddress(endpoint *kubeadmapi.APIEndpoint) string {
-	// In the case of a self-hosted deployment, the initial host on which kubeadm --init is run,
-	// will generate a DaemonSet with a nodeSelector such that all nodes with the label
-	// node-role.kubernetes.io/master='' will have the API server deployed to it. Since the init
-	// is run only once on an initial host, the API advertise address will be invalid for any
-	// future hosts that do not have the same address. Furthermore, since liveness and readiness
-	// probes do not support the Downward API we cannot dynamically set the advertise address to
-	// the node's IP. The only option then is to use localhost.
 	if endpoint != nil && endpoint.AdvertiseAddress != "" {
 		return getProbeAddress(endpoint.AdvertiseAddress)
 	}