Add Pod UID (metadata.uid) to downward API env var

pkg/api/types.go

@@ -1008,7 +1008,7 @@ type DownwardAPIVolumeSource struct {
 type DownwardAPIVolumeFile struct {
 	// Required: Path is  the relative path name of the file to be created. Must not be absolute or contain the '..' path. Must be utf-8 encoded. The first item of the relative path must not start with '..'
 	Path string
-	// Required: Selects a field of the pod: only annotations, labels, name and  namespace are supported.
+	// Required: Selects a field of the pod: only annotations, labels, name, namespace and uid are supported.
 	// +optional
 	FieldRef *ObjectFieldSelector
 	// Selects a resource of the container: only resources limits and requests
@@ -1373,7 +1373,7 @@ 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.hostIP, status.podIP.
+	// metadata.uid, 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

@@ -188,6 +188,7 @@ func addConversionFuncs(scheme *runtime.Scheme) error {
 				"metadata.labels",
 				"metadata.name",
 				"metadata.namespace",
+				"metadata.uid",
 				"spec.nodeName",
 				"spec.restartPolicy",
 				"spec.serviceAccountName",

pkg/api/validation/validation.go

@@ -804,7 +804,8 @@ var validDownwardAPIFieldPathExpressions = sets.NewString(
 	"metadata.name",
 	"metadata.namespace",
 	"metadata.labels",
-	"metadata.annotations")
+	"metadata.annotations",
+	"metadata.uid")
 
 func validateDownwardAPIVolumeFile(file *api.DownwardAPIVolumeFile, fldPath *field.Path) field.ErrorList {
 	allErrs := field.ErrorList{}
@@ -1552,7 +1553,7 @@ 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.hostIP", "status.podIP")
+var validFieldPathExpressionsEnv = sets.NewString("metadata.name", "metadata.namespace", "metadata.uid", "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

@@ -2589,6 +2589,24 @@ func TestValidateEnv(t *testing.T) {
 			ValueFrom: &api.EnvVarSource{
 				FieldRef: &api.ObjectFieldSelector{
 					APIVersion: api.Registry.GroupOrDie(api.GroupName).GroupVersion.String(),
+					FieldPath:  "metadata.namespace",
+				},
+			},
+		},
+		{
+			Name: "abc",
+			ValueFrom: &api.EnvVarSource{
+				FieldRef: &api.ObjectFieldSelector{
+					APIVersion: api.Registry.GroupOrDie(api.GroupName).GroupVersion.String(),
+					FieldPath:  "metadata.uid",
+				},
+			},
+		},
+		{
+			Name: "abc",
+			ValueFrom: &api.EnvVarSource{
+				FieldRef: &api.ObjectFieldSelector{
+					APIVersion: api.Registry.GroupOrDie(api.GroupName).GroupVersion.String(),
 					FieldPath:  "spec.nodeName",
 				},
 			},
@@ -2644,7 +2662,7 @@ func TestValidateEnv(t *testing.T) {
 		},
 	}
 	if errs := ValidateEnv(successCase, field.NewPath("field")); len(errs) != 0 {
-		t.Errorf("expected success: %v", errs)
+		t.Errorf("expected success, got: %v", errs)
 	}
 
 	errorCases := []struct {
@@ -2823,7 +2841,7 @@ 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.hostIP, status.podIP`,
+			expectedError: `[0].valueFrom.fieldRef.fieldPath: Unsupported value: "metadata.labels": supported values: metadata.name, metadata.namespace, metadata.uid, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP`,
 		},
 		{
 			name: "invalid fieldPath annotations",
@@ -2836,7 +2854,7 @@ 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.hostIP, status.podIP`,
+			expectedError: `[0].valueFrom.fieldRef.fieldPath: Unsupported value: "metadata.annotations": supported values: metadata.name, metadata.namespace, metadata.uid, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP`,
 		},
 		{
 			name: "unsupported fieldPath",
@@ -2849,7 +2867,7 @@ func TestValidateEnv(t *testing.T) {
 					},
 				},
 			}},
-			expectedError: `valueFrom.fieldRef.fieldPath: Unsupported value: "status.phase": supported values: metadata.name, metadata.namespace, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP`,
+			expectedError: `valueFrom.fieldRef.fieldPath: Unsupported value: "status.phase": supported values: metadata.name, metadata.namespace, metadata.uid, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP`,
 		},
 	}
 	for _, tc := range errorCases {

pkg/fieldpath/fieldpath.go

@@ -51,6 +51,8 @@ func ExtractFieldPathAsString(obj interface{}, fieldPath string) (string, error)
 		return accessor.GetName(), nil
 	case "metadata.namespace":
 		return accessor.GetNamespace(), nil
+	case "metadata.uid":
+		return string(accessor.GetUID()), nil
 	}
 
 	return "", fmt.Errorf("unsupported fieldPath: %v", fieldPath)