Add NominatedNodeName to PodStatus

pkg/apis/core/types.go

@@ -2724,6 +2724,13 @@ type PodStatus struct {
 	// A brief CamelCase message indicating details about why the pod is in this state. e.g. 'Evicted'
 	// +optional
 	Reason string
+	// nominatedNodeName is set when this pod preempts other pods on the node, but it cannot be
+	// scheduled right away as preemption victims receive their graceful termination periods.
+	// This field does not guarantee that the pod will be scheduled on this node. Scheduler may decide
+	// to place the pod elsewhere if other nodes become available sooner. Scheduler may also decide to
+	// give the resources on this node to a higher priority pod that is created after preemption.
+	// +optional
+	NominatedNodeName string
 
 	// +optional
 	HostIP string

pkg/apis/core/v1/conversion.go

@@ -163,7 +163,8 @@ func addConversionFuncs(scheme *runtime.Scheme) error {
 				"spec.restartPolicy",
 				"spec.schedulerName",
 				"status.phase",
-				"status.podIP":
+				"status.podIP",
+				"status.nominatedNodeName":
 				return label, value, nil
 			// This is for backwards compatibility with old v1 clients which send spec.host
 			case "spec.host":

pkg/apis/core/validation/validation.go

@@ -3374,6 +3374,12 @@ func ValidatePodStatusUpdate(newPod, oldPod *core.Pod) field.ErrorList {
 		allErrs = append(allErrs, field.Forbidden(fldPath.Child("nodeName"), "may not be changed directly"))
 	}
 
+	if newPod.Status.NominatedNodeName != oldPod.Status.NominatedNodeName && len(newPod.Status.NominatedNodeName) > 0 {
+		for _, msg := range ValidateNodeName(newPod.Status.NominatedNodeName, false) {
+			allErrs = append(allErrs, field.Invalid(fldPath.Child("nominatedNodeName"), newPod.Status.NominatedNodeName, msg))
+		}
+	}
+
 	// If pod should not restart, make sure the status update does not transition
 	// any terminated containers to a non-terminated state.
 	allErrs = append(allErrs, ValidateContainerStateTransition(newPod.Status.ContainerStatuses, oldPod.Status.ContainerStatuses, fldPath.Child("containerStatuses"), oldPod.Spec.RestartPolicy)...)

pkg/apis/core/validation/validation_test.go

@@ -7756,6 +7756,129 @@ func TestValidatePodUpdate(t *testing.T) {
 	}
 }
 
+func TestValidatePodStatusUpdate(t *testing.T) {
+	tests := []struct {
+		new  core.Pod
+		old  core.Pod
+		err  string
+		test string
+	}{
+		{
+			core.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "foo",
+				},
+				Spec: core.PodSpec{
+					NodeName: "node1",
+				},
+				Status: core.PodStatus{
+					NominatedNodeName: "node1",
+				},
+			},
+			core.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "foo",
+				},
+				Spec: core.PodSpec{
+					NodeName: "node1",
+				},
+				Status: core.PodStatus{},
+			},
+			"",
+			"removed nominatedNodeName",
+		},
+		{
+			core.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "foo",
+				},
+				Spec: core.PodSpec{
+					NodeName: "node1",
+				},
+			},
+			core.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "foo",
+				},
+				Spec: core.PodSpec{
+					NodeName: "node1",
+				},
+				Status: core.PodStatus{
+					NominatedNodeName: "node1",
+				},
+			},
+			"",
+			"add valid nominatedNodeName",
+		},
+		{
+			core.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "foo",
+				},
+				Spec: core.PodSpec{
+					NodeName: "node1",
+				},
+				Status: core.PodStatus{
+					NominatedNodeName: "Node1",
+				},
+			},
+			core.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "foo",
+				},
+				Spec: core.PodSpec{
+					NodeName: "node1",
+				},
+			},
+			"nominatedNodeName",
+			"Add invalid nominatedNodeName",
+		},
+		{
+			core.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "foo",
+				},
+				Spec: core.PodSpec{
+					NodeName: "node1",
+				},
+				Status: core.PodStatus{
+					NominatedNodeName: "node1",
+				},
+			},
+			core.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "foo",
+				},
+				Spec: core.PodSpec{
+					NodeName: "node1",
+				},
+				Status: core.PodStatus{
+					NominatedNodeName: "node2",
+				},
+			},
+			"",
+			"Update nominatedNodeName",
+		},
+	}
+
+	for _, test := range tests {
+		test.new.ObjectMeta.ResourceVersion = "1"
+		test.old.ObjectMeta.ResourceVersion = "1"
+		errs := ValidatePodStatusUpdate(&test.new, &test.old)
+		if test.err == "" {
+			if len(errs) != 0 {
+				t.Errorf("unexpected invalid: %s (%+v)\nA: %+v\nB: %+v", test.test, errs, test.new, test.old)
+			}
+		} else {
+			if len(errs) == 0 {
+				t.Errorf("unexpected valid: %s\nA: %+v\nB: %+v", test.test, test.new, test.old)
+			} else if actualErr := errs.ToAggregate().Error(); !strings.Contains(actualErr, test.err) {
+				t.Errorf("unexpected error message: %s\nExpected error: %s\nActual error: %s", test.test, test.err, actualErr)
+			}
+		}
+	}
+}
+
 func makeValidService() core.Service {
 	return core.Service{
 		ObjectMeta: metav1.ObjectMeta{

pkg/printers/internalversion/describe.go

@@ -651,6 +651,9 @@ func describePod(pod *api.Pod, events *api.EventList) (string, error) {
 		if controlledBy := printController(pod); len(controlledBy) > 0 {
 			w.Write(LEVEL_0, "Controlled By:\t%s\n", controlledBy)
 		}
+		if len(pod.Status.NominatedNodeName) > 0 {
+			w.Write(LEVEL_0, "NominatedNodeName:\t%s\n", pod.Status.NominatedNodeName)
+		}
 
 		if len(pod.Spec.InitContainers) > 0 {
 			describeContainers("Init Containers", pod.Spec.InitContainers, pod.Status.InitContainerStatuses, EnvValueRetriever(pod), w, "")

pkg/printers/internalversion/describe_test.go

@@ -81,6 +81,7 @@ func TestDescribePodNode(t *testing.T) {
 		},
 		Status: api.PodStatus{
 			HostIP:            "127.0.0.1",
+			NominatedNodeName: "nodeA",
 		},
 	})
 	c := &describeClient{T: t, Namespace: "foo", Interface: fake}
@@ -92,6 +93,9 @@ func TestDescribePodNode(t *testing.T) {
 	if !strings.Contains(out, "all-in-one/127.0.0.1") {
 		t.Errorf("unexpected out: %s", out)
 	}
+	if !strings.Contains(out, "nodeA") {
+		t.Errorf("unexpected out: %s", out)
+	}
 }
 
 func TestDescribePodTolerations(t *testing.T) {

pkg/printers/internalversion/printers.go

@@ -609,6 +609,9 @@ func printPod(pod *api.Pod, options printers.PrintOptions) ([]metav1alpha1.Table
 			nodeName = "<none>"
 		}
 		row.Cells = append(row.Cells, podIP, nodeName)
+		if len(pod.Status.NominatedNodeName) > 0 {
+			row.Cells = append(row.Cells, pod.Status.NominatedNodeName)
+		}
 	}
 
 	return []metav1alpha1.TableRow{row}, nil

pkg/printers/internalversion/printers_test.go

@@ -1704,9 +1704,10 @@ func TestPrintPodwide(t *testing.T) {
 						{Ready: true, RestartCount: 3, State: api.ContainerState{Running: &api.ContainerStateRunning{}}},
 						{RestartCount: 3},
 					},
+					NominatedNodeName: "node1",
 				},
 			},
-			[]metav1alpha1.TableRow{{Cells: []interface{}{"test1", "1/2", "podPhase", 6, "<unknown>", "1.1.1.1", "test1"}}},
+			[]metav1alpha1.TableRow{{Cells: []interface{}{"test1", "1/2", "podPhase", 6, "<unknown>", "1.1.1.1", "test1", "node1"}}},
 		},
 		{
 			// Test when the NodeName and PodIP are none

pkg/registry/core/pod/strategy.go

@@ -243,6 +243,7 @@ func PodToSelectableFields(pod *api.Pod) fields.Set {
 	podSpecificFieldsSet["spec.schedulerName"] = string(pod.Spec.SchedulerName)
 	podSpecificFieldsSet["status.phase"] = string(pod.Status.Phase)
 	podSpecificFieldsSet["status.podIP"] = string(pod.Status.PodIP)
+	podSpecificFieldsSet["status.nominatedNodeName"] = string(pod.Status.NominatedNodeName)
 	return generic.AddObjectMetaFieldsSet(podSpecificFieldsSet, &pod.ObjectMeta, true)
 }
 

pkg/registry/core/pod/strategy_test.go

@@ -114,7 +114,20 @@ func TestMatchPod(t *testing.T) {
 			fieldSelector: fields.ParseSelectorOrDie("status.podIP=4.3.2.1"),
 			expectMatch:   false,
 		},
-	}
+		{
+			in: &api.Pod{
+				Status: api.PodStatus{NominatedNodeName: "node1"},
+			},
+			fieldSelector: fields.ParseSelectorOrDie("status.nominatedNodeName=node1"),
+			expectMatch:   true,
+		},
+		{
+			in: &api.Pod{
+				Status: api.PodStatus{NominatedNodeName: "node1"},
+			},
+			fieldSelector: fields.ParseSelectorOrDie("status.nominatedNodeName=node2"),
+			expectMatch:   false,
+		}}
 	for _, testCase := range testCases {
 		m := MatchPod(labels.Everything(), testCase.fieldSelector)
 		result, err := m.Matches(testCase.in)

staging/src/k8s.io/api/core/v1/types.go

@@ -3021,6 +3021,15 @@ type PodStatus struct {
 	// e.g. 'Evicted'
 	// +optional
 	Reason string `json:"reason,omitempty" protobuf:"bytes,4,opt,name=reason"`
+	// nominatedNodeName is set only when this pod preempts other pods on the node, but it cannot be
+	// scheduled right away as preemption victims receive their graceful termination periods.
+	// This field does not guarantee that the pod will be scheduled on this node. Scheduler may decide
+	// to place the pod elsewhere if other nodes become available sooner. Scheduler may also decide to
+	// give the resources on this node to a higher priority pod that is created after preemption.
+	// As a result, this field may be different than PodSpec.nodeName when the pod is
+	// scheduled.
+	// +optional
+	NominatedNodeName string `json:"nominatedNodeName,omitempty" protobuf:"bytes,11,opt,name=nominatedNodeName"`
 
 	// IP address of the host to which the pod is assigned. Empty if not yet scheduled.
 	// +optional