Merge pull request #42717 from andrewsykim/support-host-ip-downward-api

Automatic merge from submit-queue

Support status.hostIP in downward API

**What this PR does / why we need it**:
Exposes pod's hostIP (node IP) via downward API. 

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: 
fixes https://github.com/kubernetes/kubernetes/issues/24657

**Special notes for your reviewer**:
Not sure if there's more documentation that's needed, please point me in the right direction and I will add some :)

api/openapi-spec/swagger.json

@@ -38347,7 +38347,7 @@
       "$ref": "#/definitions/io.k8s.kubernetes.pkg.api.v1.ConfigMapKeySelector"
      },
      "fieldRef": {
-      "description": "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.podIP.",
+      "description": "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP.",
       "$ref": "#/definitions/io.k8s.kubernetes.pkg.api.v1.ObjectFieldSelector"
      },
      "resourceFieldRef": {

api/swagger-spec/apps_v1beta1.json

@@ -3768,7 +3768,7 @@
     "properties": {
      "fieldRef": {
       "$ref": "v1.ObjectFieldSelector",
-      "description": "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.podIP."
+      "description": "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP."
      },
      "resourceFieldRef": {
       "$ref": "v1.ResourceFieldSelector",

api/swagger-spec/batch_v1.json

@@ -2551,7 +2551,7 @@
     "properties": {
      "fieldRef": {
       "$ref": "v1.ObjectFieldSelector",
-      "description": "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.podIP."
+      "description": "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP."
      },
      "resourceFieldRef": {
       "$ref": "v1.ResourceFieldSelector",

api/swagger-spec/batch_v2alpha1.json

@@ -3584,7 +3584,7 @@
     "properties": {
      "fieldRef": {
       "$ref": "v1.ObjectFieldSelector",
-      "description": "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.podIP."
+      "description": "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP."
      },
      "resourceFieldRef": {
       "$ref": "v1.ResourceFieldSelector",

api/swagger-spec/extensions_v1beta1.json

@@ -8015,7 +8015,7 @@
     "properties": {
      "fieldRef": {
       "$ref": "v1.ObjectFieldSelector",
-      "description": "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.podIP."
+      "description": "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP."
      },
      "resourceFieldRef": {
       "$ref": "v1.ResourceFieldSelector",

api/swagger-spec/settings.k8s.io_v1alpha1.json

@@ -1125,7 +1125,7 @@
     "properties": {
      "fieldRef": {
       "$ref": "v1.ObjectFieldSelector",
-      "description": "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.podIP."
+      "description": "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP."
      },
      "resourceFieldRef": {
       "$ref": "v1.ResourceFieldSelector",

api/swagger-spec/v1.json

@@ -19380,7 +19380,7 @@
     "properties": {
      "fieldRef": {
       "$ref": "v1.ObjectFieldSelector",
-      "description": "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.podIP."
+      "description": "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP."
      },
      "resourceFieldRef": {
       "$ref": "v1.ResourceFieldSelector",

docs/api-reference/apps/v1beta1/definitions.html

@@ -2498,7 +2498,7 @@ Populated by the system when a graceful deletion is requested. Read-only. More i
 <tbody>
 <tr>
 <td class="tableblock halign-left valign-top"><p class="tableblock">fieldRef</p></td>
-<td class="tableblock halign-left valign-top"><p class="tableblock">Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.podIP.</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP.</p></td>
 <td class="tableblock halign-left valign-top"><p class="tableblock">false</p></td>
 <td class="tableblock halign-left valign-top"><p class="tableblock"><a href="#_v1_objectfieldselector">v1.ObjectFieldSelector</a></p></td>
 <td class="tableblock halign-left valign-top"></td>
@@ -6270,7 +6270,7 @@ Examples:<br>
 </div>
 <div id="footer">
 <div id="footer-text">
-Last updated 2017-03-21 14:22:21 UTC
+Last updated 2017-03-28 17:18:11 UTC
 </div>
 </div>
 </body>

docs/api-reference/batch/v1/definitions.html

@@ -3741,7 +3741,7 @@ Populated by the system when a graceful deletion is requested. Read-only. More i
 <tbody>
 <tr>
 <td class="tableblock halign-left valign-top"><p class="tableblock">fieldRef</p></td>
-<td class="tableblock halign-left valign-top"><p class="tableblock">Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.podIP.</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP.</p></td>
 <td class="tableblock halign-left valign-top"><p class="tableblock">false</p></td>
 <td class="tableblock halign-left valign-top"><p class="tableblock"><a href="#_v1_objectfieldselector">v1.ObjectFieldSelector</a></p></td>
 <td class="tableblock halign-left valign-top"></td>
@@ -5512,7 +5512,7 @@ Examples:<br>
 </div>
 <div id="footer">
 <div id="footer-text">
-Last updated 2017-03-21 14:22:57 UTC
+Last updated 2017-03-28 17:18:59 UTC
 </div>
 </div>
 </body>

docs/api-reference/batch/v2alpha1/definitions.html

@@ -3568,7 +3568,7 @@ Populated by the system when a graceful deletion is requested. Read-only. More i
 <tbody>
 <tr>
 <td class="tableblock halign-left valign-top"><p class="tableblock">fieldRef</p></td>
-<td class="tableblock halign-left valign-top"><p class="tableblock">Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.podIP.</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP.</p></td>
 <td class="tableblock halign-left valign-top"><p class="tableblock">false</p></td>
 <td class="tableblock halign-left valign-top"><p class="tableblock"><a href="#_v1_objectfieldselector">v1.ObjectFieldSelector</a></p></td>
 <td class="tableblock halign-left valign-top"></td>
@@ -5608,7 +5608,7 @@ Examples:<br>
 </div>
 <div id="footer">
 <div id="footer-text">
-Last updated 2017-03-27 13:42:49 UTC
+Last updated 2017-03-28 20:12:14 UTC
 </div>
 </div>
 </body>

docs/api-reference/extensions/v1beta1/definitions.html

@@ -3090,7 +3090,7 @@ Populated by the system when a graceful deletion is requested. Read-only. More i
 <tbody>
 <tr>
 <td class="tableblock halign-left valign-top"><p class="tableblock">fieldRef</p></td>
-<td class="tableblock halign-left valign-top"><p class="tableblock">Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.podIP.</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP.</p></td>
 <td class="tableblock halign-left valign-top"><p class="tableblock">false</p></td>
 <td class="tableblock halign-left valign-top"><p class="tableblock"><a href="#_v1_objectfieldselector">v1.ObjectFieldSelector</a></p></td>
 <td class="tableblock halign-left valign-top"></td>
@@ -7917,7 +7917,7 @@ Both these may change in the future. Incoming requests are matched against the h
 </div>
 <div id="footer">
 <div id="footer-text">
-Last updated 2017-03-21 14:23:11 UTC
+Last updated 2017-03-28 17:19:22 UTC
 </div>
 </div>
 </body>

docs/api-reference/settings.k8s.io/v1alpha1/definitions.html

@@ -2783,7 +2783,7 @@ Populated by the system when a graceful deletion is requested. Read-only. More i
 <tbody>
 <tr>
 <td class="tableblock halign-left valign-top"><p class="tableblock">fieldRef</p></td>
-<td class="tableblock halign-left valign-top"><p class="tableblock">Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.podIP.</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP.</p></td>
 <td class="tableblock halign-left valign-top"><p class="tableblock">false</p></td>
 <td class="tableblock halign-left valign-top"><p class="tableblock"><a href="#_v1_objectfieldselector">v1.ObjectFieldSelector</a></p></td>
 <td class="tableblock halign-left valign-top"></td>
@@ -3806,7 +3806,7 @@ Examples:<br>
 </div>
 <div id="footer">
 <div id="footer-text">
-Last updated 2017-03-21 14:23:30 UTC
+Last updated 2017-03-28 17:19:50 UTC
 </div>
 </div>
 </body>

docs/api-reference/v1/definitions.html

@@ -3554,7 +3554,7 @@ The resulting set of endpoints can be viewed as:<br>
 <tbody>
 <tr>
 <td class="tableblock halign-left valign-top"><p class="tableblock">fieldRef</p></td>
-<td class="tableblock halign-left valign-top"><p class="tableblock">Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.podIP.</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP.</p></td>
 <td class="tableblock halign-left valign-top"><p class="tableblock">false</p></td>
 <td class="tableblock halign-left valign-top"><p class="tableblock"><a href="#_v1_objectfieldselector">v1.ObjectFieldSelector</a></p></td>
 <td class="tableblock halign-left valign-top"></td>
@@ -9857,7 +9857,7 @@ Examples:<br>
 </div>
 <div id="footer">
 <div id="footer-text">
-Last updated 2017-03-21 14:22:15 UTC
+Last updated 2017-03-28 17:18:02 UTC
 </div>
 </div>
 </body>

federation/apis/openapi-spec/swagger.json

@@ -9851,7 +9851,7 @@
       "$ref": "#/definitions/io.k8s.kubernetes.pkg.api.v1.ConfigMapKeySelector"
      },
      "fieldRef": {
-      "description": "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.podIP.",
+      "description": "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP.",
       "$ref": "#/definitions/io.k8s.kubernetes.pkg.api.v1.ObjectFieldSelector"
      },
      "resourceFieldRef": {

pkg/api/types.go

@@ -1250,7 +1250,7 @@ type EnvVar struct {
 // Only one of its fields may be set.
 type EnvVarSource struct {
 	// Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations,
-	// spec.nodeName, spec.serviceAccountName, status.podIP.
+	// spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP.
 	// +optional
 	FieldRef *ObjectFieldSelector
 	// Selects a resource of the container: only resources limits and requests

pkg/api/v1/conversion.go

@@ -190,6 +190,7 @@ func addConversionFuncs(scheme *runtime.Scheme) error {
 				"spec.restartPolicy",
 				"spec.serviceAccountName",
 				"status.phase",
+				"status.hostIP",
 				"status.podIP":
 				return label, value, nil
 				// This is for backwards compatibility with old v1 clients which send spec.host

pkg/api/v1/generated.proto

@@ -899,7 +899,7 @@ message EnvVar {
 // EnvVarSource represents a source for the value of an EnvVar.
 message EnvVarSource {
   // Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations,
-  // spec.nodeName, spec.serviceAccountName, status.podIP.
+  // spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP.
   // +optional
   optional ObjectFieldSelector fieldRef = 1;
 

pkg/api/v1/types.go

@@ -1349,7 +1349,7 @@ type EnvVar struct {
 // EnvVarSource represents a source for the value of an EnvVar.
 type EnvVarSource struct {
 	// Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations,
-	// spec.nodeName, spec.serviceAccountName, status.podIP.
+	// spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP.
 	// +optional
 	FieldRef *ObjectFieldSelector `json:"fieldRef,omitempty" protobuf:"bytes,1,opt,name=fieldRef"`
 	// Selects a resource of the container: only resources limits and requests

pkg/api/v1/types_swagger_doc_generated.go

@@ -481,7 +481,7 @@ func (EnvVar) SwaggerDoc() map[string]string {
 
 var map_EnvVarSource = map[string]string{
 	"":                 "EnvVarSource represents a source for the value of an EnvVar.",
-	"fieldRef":         "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.podIP.",
+	"fieldRef":         "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP.",
 	"resourceFieldRef": "Selects a resource of the container: only resources limits and requests (limits.cpu, limits.memory, requests.cpu and requests.memory) are currently supported.",
 	"configMapKeyRef":  "Selects a key of a ConfigMap.",
 	"secretKeyRef":     "Selects a key of a secret in the pod's namespace",

pkg/api/validation/validation.go

@@ -1416,7 +1416,7 @@ func ValidateEnv(vars []api.EnvVar, fldPath *field.Path) field.ErrorList {
 	return allErrs
 }
 
-var validFieldPathExpressionsEnv = sets.NewString("metadata.name", "metadata.namespace", "spec.nodeName", "spec.serviceAccountName", "status.podIP")
+var validFieldPathExpressionsEnv = sets.NewString("metadata.name", "metadata.namespace", "spec.nodeName", "spec.serviceAccountName", "status.hostIP", "status.podIP")
 var validContainerResourceFieldPathExpressions = sets.NewString("limits.cpu", "limits.memory", "requests.cpu", "requests.memory")
 
 func validateEnvVarValueFrom(ev api.EnvVar, fldPath *field.Path) field.ErrorList {

pkg/api/validation/validation_test.go

@@ -2153,6 +2153,24 @@ func TestValidateEnv(t *testing.T) {
 				},
 			},
 		},
+		{
+			Name: "abc",
+			ValueFrom: &api.EnvVarSource{
+				FieldRef: &api.ObjectFieldSelector{
+					APIVersion: api.Registry.GroupOrDie(api.GroupName).GroupVersion.String(),
+					FieldPath:  "status.hostIP",
+				},
+			},
+		},
+		{
+			Name: "abc",
+			ValueFrom: &api.EnvVarSource{
+				FieldRef: &api.ObjectFieldSelector{
+					APIVersion: api.Registry.GroupOrDie(api.GroupName).GroupVersion.String(),
+					FieldPath:  "status.podIP",
+				},
+			},
+		},
 		{
 			Name: "secret_value",
 			ValueFrom: &api.EnvVarSource{
@@ -2328,7 +2346,7 @@ func TestValidateEnv(t *testing.T) {
 					},
 				},
 			}},
-			expectedError: `[0].valueFrom.fieldRef.fieldPath: Unsupported value: "metadata.labels": supported values: metadata.name, metadata.namespace, spec.nodeName, spec.serviceAccountName, status.podIP`,
+			expectedError: `[0].valueFrom.fieldRef.fieldPath: Unsupported value: "metadata.labels": supported values: metadata.name, metadata.namespace, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP`,
 		},
 		{
 			name: "invalid fieldPath annotations",
@@ -2341,7 +2359,7 @@ func TestValidateEnv(t *testing.T) {
 					},
 				},
 			}},
-			expectedError: `[0].valueFrom.fieldRef.fieldPath: Unsupported value: "metadata.annotations": supported values: metadata.name, metadata.namespace, spec.nodeName, spec.serviceAccountName, status.podIP`,
+			expectedError: `[0].valueFrom.fieldRef.fieldPath: Unsupported value: "metadata.annotations": supported values: metadata.name, metadata.namespace, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP`,
 		},
 		{
 			name: "unsupported fieldPath",
@@ -2354,7 +2372,7 @@ func TestValidateEnv(t *testing.T) {
 					},
 				},
 			}},
-			expectedError: `valueFrom.fieldRef.fieldPath: Unsupported value: "status.phase": supported values: metadata.name, metadata.namespace, spec.nodeName, spec.serviceAccountName, status.podIP`,
+			expectedError: `valueFrom.fieldRef.fieldPath: Unsupported value: "status.phase": supported values: metadata.name, metadata.namespace, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP`,
 		},
 	}
 	for _, tc := range errorCases {

pkg/fieldpath/fieldpath.go

@@ -41,11 +41,6 @@ func FormatMap(m map[string]string) (fmtStr string) {
 // ExtractFieldPathAsString extracts the field from the given object
 // and returns it as a string.  The object must be a pointer to an
 // API type.
-//
-// Currently, this API is limited to supporting the fieldpaths:
-//
-// 1.  metadata.name - The name of an API object
-// 2.  metadata.namespace - The namespace of an API object
 func ExtractFieldPathAsString(obj interface{}, fieldPath string) (string, error) {
 	accessor, err := meta.Accessor(obj)
 	if err != nil {

pkg/generated/openapi/zz_generated.openapi.go

@@ -3355,7 +3355,7 @@ func GetOpenAPIDefinitions(ref openapi.ReferenceCallback) map[string]openapi.Ope
 					Properties: map[string]spec.Schema{
 						"fieldRef": {
 							SchemaProps: spec.SchemaProps{
-								Description: "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.podIP.",
+								Description: "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP.",
 								Ref:         ref("k8s.io/kubernetes/pkg/api/v1.ObjectFieldSelector"),
 							},
 						},

pkg/kubelet/container/helpers.go

@@ -46,7 +46,7 @@ type HandlerRunner interface {
 }
 
 // RuntimeHelper wraps kubelet to make container runtime
-// able to get necessary informations like the RunContainerOptions, DNS settings.
+// able to get necessary informations like the RunContainerOptions, DNS settings, Host IP.
 type RuntimeHelper interface {
 	GenerateRunContainerOptions(pod *v1.Pod, container *v1.Container, podIP string) (contOpts *RunContainerOptions, useClusterFirstPolicy bool, err error)
 	GetClusterDNS(pod *v1.Pod) (dnsServers []string, dnsSearches []string, useClusterFirstPolicy bool, err error)

pkg/kubelet/kubelet_pods.go

@@ -638,6 +638,12 @@ func (kl *Kubelet) podFieldSelectorRuntimeValue(fs *v1.ObjectFieldSelector, pod
 		return pod.Spec.NodeName, nil
 	case "spec.serviceAccountName":
 		return pod.Spec.ServiceAccountName, nil
+	case "status.hostIP":
+		hostIP, err := kl.getHostIPAnyWay()
+		if err != nil {
+			return "", err
+		}
+		return hostIP.String(), nil
 	case "status.podIP":
 		return podIP, nil
 	}

pkg/kubelet/kubelet_pods_test.go

@@ -502,6 +502,15 @@ func TestMakeEnvironmentVariables(t *testing.T) {
 							},
 						},
 					},
+					{
+						Name: "HOST_IP",
+						ValueFrom: &v1.EnvVarSource{
+							FieldRef: &v1.ObjectFieldSelector{
+								APIVersion: api.Registry.GroupOrDie(v1.GroupName).GroupVersion.String(),
+								FieldPath:  "status.hostIP",
+							},
+						},
+					},
 				},
 			},
 			masterServiceNs: "nothing",
@@ -512,6 +521,7 @@ func TestMakeEnvironmentVariables(t *testing.T) {
 				{Name: "POD_NODE_NAME", Value: "node-name"},
 				{Name: "POD_SERVICE_ACCOUNT_NAME", Value: "special"},
 				{Name: "POD_IP", Value: "1.2.3.4"},
+				{Name: "HOST_IP", Value: testKubeletHostIP},
 			},
 		},
 		{

pkg/kubelet/kubelet_test.go

@@ -79,6 +79,7 @@ func init() {
 
 const (
 	testKubeletHostname = "127.0.0.1"
+	testKubeletHostIP   = "127.0.0.1"
 
 	testReservationCPU    = "200m"
 	testReservationMemory = "100M"
@@ -166,7 +167,31 @@ func newTestKubeletWithImageList(
 	kubelet.masterServiceNamespace = metav1.NamespaceDefault
 	kubelet.serviceLister = testServiceLister{}
 	kubelet.nodeLister = testNodeLister{}
-	kubelet.nodeInfo = testNodeInfo{}
+	kubelet.nodeInfo = testNodeInfo{
+		nodes: []*v1.Node{
+			{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: string(kubelet.nodeName),
+				},
+				Status: v1.NodeStatus{
+					Conditions: []v1.NodeCondition{
+						{
+							Type:    v1.NodeReady,
+							Status:  v1.ConditionTrue,
+							Reason:  "Ready",
+							Message: "Node ready",
+						},
+					},
+					Addresses: []v1.NodeAddress{
+						{
+							Type:    v1.NodeInternalIP,
+							Address: testKubeletHostIP,
+						},
+					},
+				},
+			},
+		},
+	}
 	kubelet.recorder = fakeRecorder
 	if err := kubelet.setupDataDirs(); err != nil {
 		t.Fatalf("can't initialize kubelet data dirs: %v", err)

staging/src/k8s.io/client-go/pkg/api/types.go

@@ -1250,7 +1250,7 @@ type EnvVar struct {
 // Only one of its fields may be set.
 type EnvVarSource struct {
 	// Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations,
-	// spec.nodeName, spec.serviceAccountName, status.podIP.
+	// spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP.
 	// +optional
 	FieldRef *ObjectFieldSelector
 	// Selects a resource of the container: only resources limits and requests

staging/src/k8s.io/client-go/pkg/api/v1/conversion.go

@@ -190,6 +190,7 @@ func addConversionFuncs(scheme *runtime.Scheme) error {
 				"spec.restartPolicy",
 				"spec.serviceAccountName",
 				"status.phase",
+				"status.hostIP",
 				"status.podIP":
 				return label, value, nil
 				// This is for backwards compatibility with old v1 clients which send spec.host

staging/src/k8s.io/client-go/pkg/api/v1/generated.proto

@@ -899,7 +899,7 @@ message EnvVar {
 // EnvVarSource represents a source for the value of an EnvVar.
 message EnvVarSource {
   // Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations,
-  // spec.nodeName, spec.serviceAccountName, status.podIP.
+  // spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP.
   // +optional
   optional ObjectFieldSelector fieldRef = 1;
 

staging/src/k8s.io/client-go/pkg/api/v1/types.go

@@ -1349,7 +1349,7 @@ type EnvVar struct {
 // EnvVarSource represents a source for the value of an EnvVar.
 type EnvVarSource struct {
 	// Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations,
-	// spec.nodeName, spec.serviceAccountName, status.podIP.
+	// spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP.
 	// +optional
 	FieldRef *ObjectFieldSelector `json:"fieldRef,omitempty" protobuf:"bytes,1,opt,name=fieldRef"`
 	// Selects a resource of the container: only resources limits and requests

staging/src/k8s.io/client-go/pkg/api/v1/types_swagger_doc_generated.go

@@ -481,7 +481,7 @@ func (EnvVar) SwaggerDoc() map[string]string {
 
 var map_EnvVarSource = map[string]string{
 	"":                 "EnvVarSource represents a source for the value of an EnvVar.",
-	"fieldRef":         "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.podIP.",
+	"fieldRef":         "Selects a field of the pod: supports metadata.name, metadata.namespace, metadata.labels, metadata.annotations, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP.",
 	"resourceFieldRef": "Selects a resource of the container: only resources limits and requests (limits.cpu, limits.memory, requests.cpu and requests.memory) are currently supported.",
 	"configMapKeyRef":  "Selects a key of a ConfigMap.",
 	"secretKeyRef":     "Selects a key of a secret in the pod's namespace",

test/e2e/common/downward_api.go

@@ -62,7 +62,7 @@ var _ = framework.KubeDescribe("Downward API", func() {
 		testDownwardAPI(f, podName, env, expectations)
 	})
 
-	It("should provide pod IP as an env var [Conformance]", func() {
+	It("should provide pod and host IP as an env var [Conformance]", func() {
 		podName := "downward-api-" + string(uuid.NewUUID())
 		env := []v1.EnvVar{
 			{
@@ -74,10 +74,20 @@ var _ = framework.KubeDescribe("Downward API", func() {
 					},
 				},
 			},
+			{
+				Name: "HOST_IP",
+				ValueFrom: &v1.EnvVarSource{
+					FieldRef: &v1.ObjectFieldSelector{
+						APIVersion: "v1",
+						FieldPath:  "status.hostIP",
+					},
+				},
+			},
 		}
 
 		expectations := []string{
 			"POD_IP=(?:\\d+)\\.(?:\\d+)\\.(?:\\d+)\\.(?:\\d+)",
+			"HOST_IP=(?:\\d+)\\.(?:\\d+)\\.(?:\\d+)\\.(?:\\d+)",
 		}
 
 		testDownwardAPI(f, podName, env, expectations)

test/fixtures/doc-yaml/user-guide/downward-api/dapi-pod.yaml

@@ -20,4 +20,8 @@ spec:
           valueFrom:
             fieldRef:
               fieldPath: status.podIP
+        - name: MY_HOST_IP
+          valueFrom:
+            fieldRef:
+               fieldPath: status.hostIP
   restartPolicy: Never