Merge pull request #8339 from bavarianbidi/support_ubuntu_to_flatcar_updates

🐛 enable updates from CloudInit (mostly ubuntu) based KCPs to Ignition (flatcar) based KCPs

Author: k8s-ci-robot

controlplane/kubeadm/api/v1beta1/kubeadm_control_plane_webhook.go

@@ -171,6 +171,8 @@ func (in *KubeadmControlPlane) ValidateUpdate(old runtime.Object) error {
 		{spec, kubeadmConfigSpec, ignition, "*"},
 		{spec, kubeadmConfigSpec, diskSetup},
 		{spec, kubeadmConfigSpec, diskSetup, "*"},
+		{spec, kubeadmConfigSpec, "format"},
+		{spec, kubeadmConfigSpec, "mounts"},
 		{spec, "machineTemplate", "metadata"},
 		{spec, "machineTemplate", "metadata", "*"},
 		{spec, "machineTemplate", "infrastructureRef", "apiVersion"},
@@ -197,12 +199,6 @@ func (in *KubeadmControlPlane) ValidateUpdate(old runtime.Object) error {
 		return apierrors.NewBadRequest(fmt.Sprintf("expecting KubeadmControlPlane but got a %T", old))
 	}
 
-	// NOTE: Defaulting for the format field has been added in v1.1.0 after implementing ignition support.
-	// This allows existing KCP objects to pick up the new default.
-	if prev.Spec.KubeadmConfigSpec.Format == "" && in.Spec.KubeadmConfigSpec.Format == bootstrapv1.CloudConfig {
-		allowedPaths = append(allowedPaths, []string{spec, kubeadmConfigSpec, "format"})
-	}
-
 	originalJSON, err := json.Marshal(prev)
 	if err != nil {
 		return apierrors.NewInternalError(err)

controlplane/kubeadm/api/v1beta1/kubeadm_control_plane_webhook_test.go

@@ -663,6 +663,12 @@ func TestKubeadmControlPlaneValidateUpdate(t *testing.T) {
 		},
 	}
 
+	switchFromCloudInitToIgnition := before.DeepCopy()
+	switchFromCloudInitToIgnition.Spec.KubeadmConfigSpec.Format = bootstrapv1.Ignition
+	switchFromCloudInitToIgnition.Spec.KubeadmConfigSpec.Mounts = []bootstrapv1.MountPoints{
+		{"/var/lib/testdir", "/var/lib/etcd/data"},
+	}
+
 	tests := []struct {
 		name                  string
 		enableIgnitionFeature bool
@@ -1001,6 +1007,13 @@ func TestKubeadmControlPlaneValidateUpdate(t *testing.T) {
 			before:                validIgnitionConfigurationBefore,
 			kcp:                   validIgnitionConfigurationAfter,
 		},
+		{
+			name:                  "should succeed when CloudInit was used before",
+			enableIgnitionFeature: true,
+			expectErr:             false,
+			before:                before,
+			kcp:                   switchFromCloudInitToIgnition,
+		},
 	}
 
 	for _, tt := range tests {