Merge pull request #37871 from Random-Liu/use-patch-in-kubelet

Automatic merge from submit-queue (batch tested with PRs 36692, 37871)

Use PatchStatus to update node status in kubelet.

Fixes https://github.com/kubernetes/kubernetes/issues/37771.

This PR changes kubelet to update node status with `PatchStatus`.

@caesarxuchao @ymqytw told me that there is a limitation of current `CreateTwoWayMergePatch`, it doesn't support primitive type slice which uses strategic merge.
* I checked the node status, the only primitive type slices in NodeStatus are as follows, they are not using strategic merge:
  * [`ContainerImage.Names`](https://github.com/kubernetes/kubernetes/blob/master/pkg/api/v1/types.go#L2963)
  * [`VolumesInUse`](https://github.com/kubernetes/kubernetes/blob/master/pkg/api/v1/types.go#L2909)
* Volume package is already [using `CreateStrategicMergePath` to generate node status update patch](https://github.com/kubernetes/kubernetes/blob/master/pkg/controller/volume/attachdetach/statusupdater/node_status_updater.go#L111), and till now everything is fine. 

@yujuhong @dchen1107 
/cc @kubernetes/sig-node

pkg/controller/volume/attachdetach/statusupdater/node_status_updater.go

@@ -91,6 +91,7 @@ func (nsu *nodeStatusUpdater) UpdateNodeStatuses() error {
 				clonedNode)
 		}
 
+		// TODO: Change to pkg/util/node.UpdateNodeStatus.
 		oldData, err := json.Marshal(node)
 		if err != nil {
 			return fmt.Errorf(

pkg/kubelet/BUILD

@@ -51,6 +51,7 @@ go_library(
         "//pkg/client/clientset_generated/release_1_5:go_default_library",
         "//pkg/client/record:go_default_library",
         "//pkg/cloudprovider:go_default_library",
+        "//pkg/conversion:go_default_library",
         "//pkg/fieldpath:go_default_library",
         "//pkg/fields:go_default_library",
         "//pkg/kubelet/api:go_default_library",
@@ -192,6 +193,7 @@ go_test(
         "//pkg/util/rand:go_default_library",
         "//pkg/util/runtime:go_default_library",
         "//pkg/util/sets:go_default_library",
+        "//pkg/util/strategicpatch:go_default_library",
         "//pkg/util/testing:go_default_library",
         "//pkg/util/uuid:go_default_library",
         "//pkg/util/wait:go_default_library",

pkg/kubelet/kubelet_node_status.go

@@ -32,11 +32,14 @@ import (
 	"k8s.io/kubernetes/pkg/api/v1"
 	metav1 "k8s.io/kubernetes/pkg/apis/meta/v1"
 	"k8s.io/kubernetes/pkg/cloudprovider"
+	"k8s.io/kubernetes/pkg/conversion"
 	"k8s.io/kubernetes/pkg/fields"
 	"k8s.io/kubernetes/pkg/kubelet/cadvisor"
 	"k8s.io/kubernetes/pkg/kubelet/events"
 	"k8s.io/kubernetes/pkg/kubelet/util/sliceutils"
+	"k8s.io/kubernetes/pkg/types"
 	utilnet "k8s.io/kubernetes/pkg/util/net"
+	nodeutil "k8s.io/kubernetes/pkg/util/node"
 	"k8s.io/kubernetes/pkg/version"
 	"k8s.io/kubernetes/pkg/volume/util/volumehelper"
 )
@@ -110,6 +113,18 @@ func (kl *Kubelet) tryRegisterWithApiServer(node *v1.Node) bool {
 		return false
 	}
 
+	clonedNode, err := conversion.NewCloner().DeepCopy(existingNode)
+	if err != nil {
+		glog.Errorf("Unable to clone %q node object %#v: %v", kl.nodeName, existingNode, err)
+		return false
+	}
+
+	originalNode, ok := clonedNode.(*v1.Node)
+	if !ok || originalNode == nil {
+		glog.Errorf("Unable to cast %q node object %#v to v1.Node", kl.nodeName, clonedNode)
+		return false
+	}
+
 	if existingNode.Spec.ExternalID == node.Spec.ExternalID {
 		glog.Infof("Node %s was previously registered", kl.nodeName)
 
@@ -118,7 +133,8 @@ func (kl *Kubelet) tryRegisterWithApiServer(node *v1.Node) bool {
 		// annotation.
 		requiresUpdate := kl.reconcileCMADAnnotationWithExistingNode(node, existingNode)
 		if requiresUpdate {
-			if _, err := kl.kubeClient.Core().Nodes().UpdateStatus(existingNode); err != nil {
+			if _, err := nodeutil.PatchNodeStatus(kl.kubeClient, types.NodeName(kl.nodeName),
+				originalNode, existingNode); err != nil {
 				glog.Errorf("Unable to reconcile node %q with API server: error updating node: %v", kl.nodeName, err)
 				return false
 			}
@@ -347,20 +363,30 @@ func (kl *Kubelet) tryUpdateNodeStatus(tryNumber int) error {
 	}
 	node := &nodes.Items[0]
 
+	clonedNode, err := conversion.NewCloner().DeepCopy(node)
+	if err != nil {
+		return fmt.Errorf("error clone node %q: %v", kl.nodeName, err)
+	}
+
+	originalNode, ok := clonedNode.(*v1.Node)
+	if !ok || originalNode == nil {
+		return fmt.Errorf("failed to cast %q node object %#v to v1.Node", kl.nodeName, clonedNode)
+	}
+
 	kl.updatePodCIDR(node.Spec.PodCIDR)
 
 	if err := kl.setNodeStatus(node); err != nil {
 		return err
 	}
-	// Update the current status on the API server
-	updatedNode, err := kl.kubeClient.Core().Nodes().UpdateStatus(node)
+	// Patch the current status on the API server
+	updatedNode, err := nodeutil.PatchNodeStatus(kl.kubeClient, types.NodeName(kl.nodeName), originalNode, node)
+	if err != nil {
+		return err
+	}
 	// If update finishes sucessfully, mark the volumeInUse as reportedInUse to indicate
 	// those volumes are already updated in the node's status
-	if err == nil {
-		kl.volumeManager.MarkVolumesAsReportedInUse(
-			updatedNode.Status.VolumesInUse)
-	}
-	return err
+	kl.volumeManager.MarkVolumesAsReportedInUse(updatedNode.Status.VolumesInUse)
+	return nil
 }
 
 // recordNodeStatusEvent records an event of the given type with the given

pkg/kubelet/kubelet_node_status_test.go

@@ -17,6 +17,7 @@ limitations under the License.
 package kubelet
 
 import (
+	"encoding/json"
 	"fmt"
 	"reflect"
 	goruntime "runtime"
@@ -39,6 +40,7 @@ import (
 	"k8s.io/kubernetes/pkg/runtime"
 	"k8s.io/kubernetes/pkg/util/diff"
 	"k8s.io/kubernetes/pkg/util/rand"
+	"k8s.io/kubernetes/pkg/util/strategicpatch"
 	"k8s.io/kubernetes/pkg/util/uuid"
 	"k8s.io/kubernetes/pkg/util/wait"
 	"k8s.io/kubernetes/pkg/version"
@@ -90,6 +92,23 @@ func generateImageTags() []string {
 	return tagList
 }
 
+func applyNodeStatusPatch(originalNode *v1.Node, patch []byte) (*v1.Node, error) {
+	original, err := json.Marshal(originalNode)
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal original node %#v: %v", originalNode, err)
+	}
+	updated, err := strategicpatch.StrategicMergePatch(original, patch, v1.Node{})
+	if err != nil {
+		return nil, fmt.Errorf("failed to apply strategic merge patch %q on node %#v: %v",
+			patch, originalNode, err)
+	}
+	updatedNode := &v1.Node{}
+	if err := json.Unmarshal(updated, updatedNode); err != nil {
+		return nil, fmt.Errorf("failed to unmarshal updated node %q: %v", updated, err)
+	}
+	return updatedNode, nil
+}
+
 func TestUpdateNewNodeStatus(t *testing.T) {
 	// generate one more than maxImagesInNodeStatus in inputImageList
 	inputImageList, expectedImageList := generateTestingImageList(maxImagesInNodeStatus + 1)
@@ -97,9 +116,8 @@ func TestUpdateNewNodeStatus(t *testing.T) {
 		t, inputImageList, false /* controllerAttachDetachEnabled */)
 	kubelet := testKubelet.kubelet
 	kubeClient := testKubelet.fakeKubeClient
-	kubeClient.ReactionChain = fake.NewSimpleClientset(&v1.NodeList{Items: []v1.Node{
-		{ObjectMeta: v1.ObjectMeta{Name: testKubeletHostname}},
-	}}).ReactionChain
+	existingNode := v1.Node{ObjectMeta: v1.ObjectMeta{Name: testKubeletHostname}}
+	kubeClient.ReactionChain = fake.NewSimpleClientset(&v1.NodeList{Items: []v1.Node{existingNode}}).ReactionChain
 	machineInfo := &cadvisorapi.MachineInfo{
 		MachineID:      "123",
 		SystemUUID:     "abc",
@@ -200,12 +218,12 @@ func TestUpdateNewNodeStatus(t *testing.T) {
 	if len(actions) != 2 {
 		t.Fatalf("unexpected actions: %v", actions)
 	}
-	if !actions[1].Matches("update", "nodes") || actions[1].GetSubresource() != "status" {
+	if !actions[1].Matches("patch", "nodes") || actions[1].GetSubresource() != "status" {
 		t.Fatalf("unexpected actions: %v", actions)
 	}
-	updatedNode, ok := actions[1].(core.UpdateAction).GetObject().(*v1.Node)
-	if !ok {
-		t.Errorf("unexpected object type")
+	updatedNode, err := applyNodeStatusPatch(&existingNode, actions[1].(core.PatchActionImpl).GetPatch())
+	if err != nil {
+		t.Fatalf("can't apply node status patch: %v", err)
 	}
 	for i, cond := range updatedNode.Status.Conditions {
 		if cond.LastHeartbeatTime.IsZero() {
@@ -237,9 +255,8 @@ func TestUpdateNewNodeOutOfDiskStatusWithTransitionFrequency(t *testing.T) {
 	testKubelet := newTestKubelet(t, false /* controllerAttachDetachEnabled */)
 	kubelet := testKubelet.kubelet
 	kubeClient := testKubelet.fakeKubeClient
-	kubeClient.ReactionChain = fake.NewSimpleClientset(&v1.NodeList{Items: []v1.Node{
-		{ObjectMeta: v1.ObjectMeta{Name: testKubeletHostname}},
-	}}).ReactionChain
+	existingNode := v1.Node{ObjectMeta: v1.ObjectMeta{Name: testKubeletHostname}}
+	kubeClient.ReactionChain = fake.NewSimpleClientset(&v1.NodeList{Items: []v1.Node{existingNode}}).ReactionChain
 	machineInfo := &cadvisorapi.MachineInfo{
 		MachineID:      "123",
 		SystemUUID:     "abc",
@@ -280,12 +297,13 @@ func TestUpdateNewNodeOutOfDiskStatusWithTransitionFrequency(t *testing.T) {
 	if len(actions) != 2 {
 		t.Fatalf("unexpected actions: %v", actions)
 	}
-	if !actions[1].Matches("update", "nodes") || actions[1].GetSubresource() != "status" {
+	// StrategicMergePatch(original, patch []byte, dataStruct interface{}) ([]byte, error)
+	if !actions[1].Matches("patch", "nodes") || actions[1].GetSubresource() != "status" {
 		t.Fatalf("unexpected actions: %v", actions)
 	}
-	updatedNode, ok := actions[1].(core.UpdateAction).GetObject().(*v1.Node)
-	if !ok {
-		t.Errorf("unexpected object type")
+	updatedNode, err := applyNodeStatusPatch(&existingNode, actions[1].(core.PatchActionImpl).GetPatch())
+	if err != nil {
+		t.Fatalf("can't apply node status patch: %v", err)
 	}
 
 	var oodCondition v1.NodeCondition
@@ -312,58 +330,57 @@ func TestUpdateExistingNodeStatus(t *testing.T) {
 	testKubelet := newTestKubelet(t, false /* controllerAttachDetachEnabled */)
 	kubelet := testKubelet.kubelet
 	kubeClient := testKubelet.fakeKubeClient
-	kubeClient.ReactionChain = fake.NewSimpleClientset(&v1.NodeList{Items: []v1.Node{
-		{
-			ObjectMeta: v1.ObjectMeta{Name: testKubeletHostname},
-			Spec:       v1.NodeSpec{},
-			Status: v1.NodeStatus{
-				Conditions: []v1.NodeCondition{
-					{
-						Type:               v1.NodeOutOfDisk,
-						Status:             v1.ConditionTrue,
-						Reason:             "KubeletOutOfDisk",
-						Message:            "out of disk space",
-						LastHeartbeatTime:  metav1.Date(2012, 1, 1, 0, 0, 0, 0, time.UTC),
-						LastTransitionTime: metav1.Date(2012, 1, 1, 0, 0, 0, 0, time.UTC),
-					},
-					{
-						Type:               v1.NodeMemoryPressure,
-						Status:             v1.ConditionFalse,
-						Reason:             "KubeletHasSufficientMemory",
-						Message:            fmt.Sprintf("kubelet has sufficient memory available"),
-						LastHeartbeatTime:  metav1.Date(2012, 1, 1, 0, 0, 0, 0, time.UTC),
-						LastTransitionTime: metav1.Date(2012, 1, 1, 0, 0, 0, 0, time.UTC),
-					},
-					{
-						Type:               v1.NodeDiskPressure,
-						Status:             v1.ConditionFalse,
-						Reason:             "KubeletHasSufficientDisk",
-						Message:            fmt.Sprintf("kubelet has sufficient disk space available"),
-						LastHeartbeatTime:  metav1.Date(2012, 1, 1, 0, 0, 0, 0, time.UTC),
-						LastTransitionTime: metav1.Date(2012, 1, 1, 0, 0, 0, 0, time.UTC),
-					},
-					{
-						Type:               v1.NodeReady,
-						Status:             v1.ConditionTrue,
-						Reason:             "KubeletReady",
-						Message:            fmt.Sprintf("kubelet is posting ready status"),
-						LastHeartbeatTime:  metav1.Date(2012, 1, 1, 0, 0, 0, 0, time.UTC),
-						LastTransitionTime: metav1.Date(2012, 1, 1, 0, 0, 0, 0, time.UTC),
-					},
+	existingNode := v1.Node{
+		ObjectMeta: v1.ObjectMeta{Name: testKubeletHostname},
+		Spec:       v1.NodeSpec{},
+		Status: v1.NodeStatus{
+			Conditions: []v1.NodeCondition{
+				{
+					Type:               v1.NodeOutOfDisk,
+					Status:             v1.ConditionTrue,
+					Reason:             "KubeletOutOfDisk",
+					Message:            "out of disk space",
+					LastHeartbeatTime:  metav1.Date(2012, 1, 1, 0, 0, 0, 0, time.UTC),
+					LastTransitionTime: metav1.Date(2012, 1, 1, 0, 0, 0, 0, time.UTC),
 				},
-				Capacity: v1.ResourceList{
-					v1.ResourceCPU:    *resource.NewMilliQuantity(3000, resource.DecimalSI),
-					v1.ResourceMemory: *resource.NewQuantity(20E9, resource.BinarySI),
-					v1.ResourcePods:   *resource.NewQuantity(0, resource.DecimalSI),
+				{
+					Type:               v1.NodeMemoryPressure,
+					Status:             v1.ConditionFalse,
+					Reason:             "KubeletHasSufficientMemory",
+					Message:            fmt.Sprintf("kubelet has sufficient memory available"),
+					LastHeartbeatTime:  metav1.Date(2012, 1, 1, 0, 0, 0, 0, time.UTC),
+					LastTransitionTime: metav1.Date(2012, 1, 1, 0, 0, 0, 0, time.UTC),
 				},
-				Allocatable: v1.ResourceList{
-					v1.ResourceCPU:    *resource.NewMilliQuantity(2800, resource.DecimalSI),
-					v1.ResourceMemory: *resource.NewQuantity(19900E6, resource.BinarySI),
-					v1.ResourcePods:   *resource.NewQuantity(0, resource.DecimalSI),
+				{
+					Type:               v1.NodeDiskPressure,
+					Status:             v1.ConditionFalse,
+					Reason:             "KubeletHasSufficientDisk",
+					Message:            fmt.Sprintf("kubelet has sufficient disk space available"),
+					LastHeartbeatTime:  metav1.Date(2012, 1, 1, 0, 0, 0, 0, time.UTC),
+					LastTransitionTime: metav1.Date(2012, 1, 1, 0, 0, 0, 0, time.UTC),
+				},
+				{
+					Type:               v1.NodeReady,
+					Status:             v1.ConditionTrue,
+					Reason:             "KubeletReady",
+					Message:            fmt.Sprintf("kubelet is posting ready status"),
+					LastHeartbeatTime:  metav1.Date(2012, 1, 1, 0, 0, 0, 0, time.UTC),
+					LastTransitionTime: metav1.Date(2012, 1, 1, 0, 0, 0, 0, time.UTC),
 				},
 			},
+			Capacity: v1.ResourceList{
+				v1.ResourceCPU:    *resource.NewMilliQuantity(3000, resource.DecimalSI),
+				v1.ResourceMemory: *resource.NewQuantity(20E9, resource.BinarySI),
+				v1.ResourcePods:   *resource.NewQuantity(0, resource.DecimalSI),
+			},
+			Allocatable: v1.ResourceList{
+				v1.ResourceCPU:    *resource.NewMilliQuantity(2800, resource.DecimalSI),
+				v1.ResourceMemory: *resource.NewQuantity(19900E6, resource.BinarySI),
+				v1.ResourcePods:   *resource.NewQuantity(0, resource.DecimalSI),
+			},
 		},
-	}}).ReactionChain
+	}
+	kubeClient.ReactionChain = fake.NewSimpleClientset(&v1.NodeList{Items: []v1.Node{existingNode}}).ReactionChain
 	mockCadvisor := testKubelet.fakeCadvisor
 	mockCadvisor.On("Start").Return(nil)
 	machineInfo := &cadvisorapi.MachineInfo{
@@ -474,13 +491,13 @@ func TestUpdateExistingNodeStatus(t *testing.T) {
 	if len(actions) != 2 {
 		t.Errorf("unexpected actions: %v", actions)
 	}
-	updateAction, ok := actions[1].(core.UpdateAction)
+	patchAction, ok := actions[1].(core.PatchActionImpl)
 	if !ok {
-		t.Errorf("unexpected action type.  expected UpdateAction, got %#v", actions[1])
+		t.Errorf("unexpected action type.  expected PatchActionImpl, got %#v", actions[1])
 	}
-	updatedNode, ok := updateAction.GetObject().(*v1.Node)
+	updatedNode, err := applyNodeStatusPatch(&existingNode, patchAction.GetPatch())
 	if !ok {
-		t.Errorf("unexpected object type")
+		t.Fatalf("can't apply node status patch: %v", err)
 	}
 	for i, cond := range updatedNode.Status.Conditions {
 		// Expect LastProbeTime to be updated to Now, while LastTransitionTime to be the same.
@@ -508,33 +525,35 @@ func TestUpdateExistingNodeOutOfDiskStatusWithTransitionFrequency(t *testing.T)
 	testKubelet := newTestKubelet(t, false /* controllerAttachDetachEnabled */)
 	kubelet := testKubelet.kubelet
 	clock := testKubelet.fakeClock
+	// Do not set nano second, because apiserver function doesn't support nano second. (Only support
+	// RFC3339).
+	clock.SetTime(time.Unix(123456, 0))
 	kubeClient := testKubelet.fakeKubeClient
-	kubeClient.ReactionChain = fake.NewSimpleClientset(&v1.NodeList{Items: []v1.Node{
-		{
-			ObjectMeta: v1.ObjectMeta{Name: testKubeletHostname},
-			Spec:       v1.NodeSpec{},
-			Status: v1.NodeStatus{
-				Conditions: []v1.NodeCondition{
-					{
-						Type:               v1.NodeReady,
-						Status:             v1.ConditionTrue,
-						Reason:             "KubeletReady",
-						Message:            fmt.Sprintf("kubelet is posting ready status"),
-						LastHeartbeatTime:  metav1.NewTime(clock.Now()),
-						LastTransitionTime: metav1.NewTime(clock.Now()),
-					},
-					{
-						Type:               v1.NodeOutOfDisk,
-						Status:             v1.ConditionTrue,
-						Reason:             "KubeletOutOfDisk",
-						Message:            "out of disk space",
-						LastHeartbeatTime:  metav1.NewTime(clock.Now()),
-						LastTransitionTime: metav1.NewTime(clock.Now()),
-					},
+	existingNode := v1.Node{
+		ObjectMeta: v1.ObjectMeta{Name: testKubeletHostname},
+		Spec:       v1.NodeSpec{},
+		Status: v1.NodeStatus{
+			Conditions: []v1.NodeCondition{
+				{
+					Type:               v1.NodeReady,
+					Status:             v1.ConditionTrue,
+					Reason:             "KubeletReady",
+					Message:            fmt.Sprintf("kubelet is posting ready status"),
+					LastHeartbeatTime:  metav1.NewTime(clock.Now()),
+					LastTransitionTime: metav1.NewTime(clock.Now()),
+				},
+				{
+					Type:               v1.NodeOutOfDisk,
+					Status:             v1.ConditionTrue,
+					Reason:             "KubeletOutOfDisk",
+					Message:            "out of disk space",
+					LastHeartbeatTime:  metav1.NewTime(clock.Now()),
+					LastTransitionTime: metav1.NewTime(clock.Now()),
 				},
 			},
 		},
-	}}).ReactionChain
+	}
+	kubeClient.ReactionChain = fake.NewSimpleClientset(&v1.NodeList{Items: []v1.Node{existingNode}}).ReactionChain
 	mockCadvisor := testKubelet.fakeCadvisor
 	machineInfo := &cadvisorapi.MachineInfo{
 		MachineID:      "123",
@@ -637,13 +656,13 @@ func TestUpdateExistingNodeOutOfDiskStatusWithTransitionFrequency(t *testing.T)
 		if len(actions) != 2 {
 			t.Errorf("%d. unexpected actions: %v", tcIdx, actions)
 		}
-		updateAction, ok := actions[1].(core.UpdateAction)
+		patchAction, ok := actions[1].(core.PatchActionImpl)
 		if !ok {
-			t.Errorf("%d. unexpected action type.  expected UpdateAction, got %#v", tcIdx, actions[1])
+			t.Errorf("%d. unexpected action type.  expected PatchActionImpl, got %#v", tcIdx, actions[1])
 		}
-		updatedNode, ok := updateAction.GetObject().(*v1.Node)
-		if !ok {
-			t.Errorf("%d. unexpected object type", tcIdx)
+		updatedNode, err := applyNodeStatusPatch(&existingNode, patchAction.GetPatch())
+		if err != nil {
+			t.Fatalf("can't apply node status patch: %v", err)
 		}
 		kubeClient.ClearActions()
 
@@ -656,7 +675,6 @@ func TestUpdateExistingNodeOutOfDiskStatusWithTransitionFrequency(t *testing.T)
 
 		if !reflect.DeepEqual(tc.expected, oodCondition) {
 			t.Errorf("%d.\nunexpected objects: %s", tcIdx, diff.ObjectDiff(tc.expected, oodCondition))
-
 		}
 	}
 }
@@ -666,9 +684,8 @@ func TestUpdateNodeStatusWithRuntimeStateError(t *testing.T) {
 	kubelet := testKubelet.kubelet
 	clock := testKubelet.fakeClock
 	kubeClient := testKubelet.fakeKubeClient
-	kubeClient.ReactionChain = fake.NewSimpleClientset(&v1.NodeList{Items: []v1.Node{
-		{ObjectMeta: v1.ObjectMeta{Name: testKubeletHostname}},
-	}}).ReactionChain
+	existingNode := v1.Node{ObjectMeta: v1.ObjectMeta{Name: testKubeletHostname}}
+	kubeClient.ReactionChain = fake.NewSimpleClientset(&v1.NodeList{Items: []v1.Node{existingNode}}).ReactionChain
 	mockCadvisor := testKubelet.fakeCadvisor
 	mockCadvisor.On("Start").Return(nil)
 	machineInfo := &cadvisorapi.MachineInfo{
@@ -772,12 +789,12 @@ func TestUpdateNodeStatusWithRuntimeStateError(t *testing.T) {
 		if len(actions) != 2 {
 			t.Fatalf("unexpected actions: %v", actions)
 		}
-		if !actions[1].Matches("update", "nodes") || actions[1].GetSubresource() != "status" {
+		if !actions[1].Matches("patch", "nodes") || actions[1].GetSubresource() != "status" {
 			t.Fatalf("unexpected actions: %v", actions)
 		}
-		updatedNode, ok := actions[1].(core.UpdateAction).GetObject().(*v1.Node)
-		if !ok {
-			t.Errorf("unexpected action type.  expected UpdateAction, got %#v", actions[1])
+		updatedNode, err := applyNodeStatusPatch(&existingNode, actions[1].(core.PatchActionImpl).GetPatch())
+		if err != nil {
+			t.Fatalf("can't apply node status patch: %v", err)
 		}
 
 		for i, cond := range updatedNode.Status.Conditions {
@@ -984,7 +1001,7 @@ func TestTryRegisterWithApiServer(t *testing.T) {
 		existingNode    *v1.Node
 		createError     error
 		getError        error
-		updateError     error
+		patchError      error
 		deleteError     error
 		expectedResult  bool
 		expectedActions int
@@ -1056,7 +1073,7 @@ func TestTryRegisterWithApiServer(t *testing.T) {
 			newNode:         newNode(false, "a"),
 			createError:     alreadyExists,
 			existingNode:    newNode(true, "a"),
-			updateError:     conflict,
+			patchError:      conflict,
 			expectedResult:  false,
 			expectedActions: 3,
 		},
@@ -1087,9 +1104,9 @@ func TestTryRegisterWithApiServer(t *testing.T) {
 			// Return an existing (matching) node on get.
 			return true, tc.existingNode, tc.getError
 		})
-		kubeClient.AddReactor("update", "nodes", func(action core.Action) (bool, runtime.Object, error) {
+		kubeClient.AddReactor("patch", "nodes", func(action core.Action) (bool, runtime.Object, error) {
 			if action.GetSubresource() == "status" {
-				return true, nil, tc.updateError
+				return true, nil, tc.patchError
 			}
 			return notImplemented(action)
 		})
@@ -1124,11 +1141,12 @@ func TestTryRegisterWithApiServer(t *testing.T) {
 					t.Errorf("%v: unexpected type; couldn't convert to *v1.Node: %+v", tc.name, createAction.GetObject())
 					continue
 				}
-			} else if action.GetVerb() == "update" {
-				updateAction := action.(core.UpdateAction)
-				savedNode, ok = updateAction.GetObject().(*v1.Node)
-				if !ok {
-					t.Errorf("%v: unexpected type; couldn't convert to *v1.Node: %+v", tc.name, updateAction.GetObject())
+			} else if action.GetVerb() == "patch" {
+				patchAction := action.(core.PatchActionImpl)
+				var err error
+				savedNode, err = applyNodeStatusPatch(tc.existingNode, patchAction.GetPatch())
+				if err != nil {
+					t.Errorf("can't apply node status patch: %v", err)
 					continue
 				}
 			}

pkg/util/node/BUILD

@@ -20,6 +20,7 @@ go_library(
         "//pkg/apis/meta/v1:go_default_library",
         "//pkg/client/clientset_generated/release_1_5:go_default_library",
         "//pkg/types:go_default_library",
+        "//pkg/util/strategicpatch:go_default_library",
         "//vendor:github.com/golang/glog",
     ],
 )

pkg/util/node/node.go

@@ -30,6 +30,7 @@ import (
 	metav1 "k8s.io/kubernetes/pkg/apis/meta/v1"
 	clientset "k8s.io/kubernetes/pkg/client/clientset_generated/release_1_5"
 	"k8s.io/kubernetes/pkg/types"
+	"k8s.io/kubernetes/pkg/util/strategicpatch"
 )
 
 const (
@@ -153,3 +154,32 @@ func SetNodeCondition(c clientset.Interface, node types.NodeName, condition v1.N
 	_, err = c.Core().Nodes().PatchStatus(string(node), patch)
 	return err
 }
+
+// PatchNodeStatus patches node status.
+func PatchNodeStatus(c clientset.Interface, nodeName types.NodeName, oldNode *v1.Node, newNode *v1.Node) (*v1.Node, error) {
+	oldData, err := json.Marshal(oldNode)
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal old node %#v for node %q: %v", oldNode, nodeName, err)
+	}
+
+	// Reset spec to make sure only patch for Status or ObjectMeta is generated.
+	// Note that we don't reset ObjectMeta here, because:
+	// 1. This aligns with Nodes().UpdateStatus().
+	// 2. Some component does use this to update node annotations.
+	newNode.Spec = oldNode.Spec
+	newData, err := json.Marshal(newNode)
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal new node %#v for node %q: %v", newNode, nodeName, err)
+	}
+
+	patchBytes, err := strategicpatch.CreateTwoWayMergePatch(oldData, newData, v1.Node{})
+	if err != nil {
+		return nil, fmt.Errorf("failed to create patch for node %q: %v", nodeName, err)
+	}
+
+	updatedNode, err := c.Core().Nodes().Patch(string(nodeName), api.StrategicMergePatchType, patchBytes, "status")
+	if err != nil {
+		return nil, fmt.Errorf("failed to patch status %q for node %q: %v", patchBytes, nodeName, err)
+	}
+	return updatedNode, nil
+}