Support exposing single annotations/labels via env downward API

Author: wondywang

virtualcluster/pkg/syncer/conversion/mutate.go

@@ -19,8 +19,6 @@ package conversion
 import (
 "context"
 "fmt"
-"strings"
-
 v1 "k8s.io/api/core/v1"
 metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 "k8s.io/klog/v2"
@@ -226,18 +224,14 @@ func mutateDownwardAPIField(env *v1.EnvVar, vPod *v1.Pod) {
 if env.ValueFrom.FieldRef == nil {
 return
 }
-if !strings.HasPrefix(env.ValueFrom.FieldRef.FieldPath, "metadata") {
-return
-}
 switch env.ValueFrom.FieldRef.FieldPath {
-case "metadata.name":
-env.Value = vPod.Name
 case "metadata.namespace":
 env.Value = vPod.Namespace
+env.ValueFrom = nil
 case "metadata.uid":
 env.Value = string(vPod.UID)
+env.ValueFrom = nil
 }
-env.ValueFrom = nil
 }
 
 func getServiceEnvVarMap(ns, cluster string, enableServiceLinks *bool, services []*v1.Service) (string, map[string]string) {

virtualcluster/pkg/syncer/conversion/mutate_test.go

@@ -86,8 +86,13 @@ func Test_mutateDownwardAPIField(t *testing.T) {
 },
 },
 expectedEnv: &v1.EnvVar{
-Name: "env_name",
-Value: aPod.Name,
+Name: "env_name",
+ValueFrom: &v1.EnvVarSource{
+FieldRef: &v1.ObjectFieldSelector{
+APIVersion: "v1",
+FieldPath: "metadata.name",
+},
+},
 },
 },
 {
@@ -124,6 +129,50 @@ func Test_mutateDownwardAPIField(t *testing.T) {
 Value: string(aPod.UID),
 },
 },
+{
+name: "env with metadata.annotations",
+pod: aPod,
+env: &v1.EnvVar{
+Name: "env_name",
+ValueFrom: &v1.EnvVarSource{
+FieldRef: &v1.ObjectFieldSelector{
+APIVersion: "v1",
+FieldPath: "metadata.annotations['anno1']",
+},
+},
+},
+expectedEnv: &v1.EnvVar{
+Name: "env_name",
+ValueFrom: &v1.EnvVarSource{
+FieldRef: &v1.ObjectFieldSelector{
+APIVersion: "v1",
+FieldPath: "metadata.annotations['anno1']",
+},
+},
+},
+},
+{
+name: "env with metadata.labels",
+pod: aPod,
+env: &v1.EnvVar{
+Name: "env_name",
+ValueFrom: &v1.EnvVarSource{
+FieldRef: &v1.ObjectFieldSelector{
+APIVersion: "v1",
+FieldPath: "metadata.labels['label1']",
+},
+},
+},
+expectedEnv: &v1.EnvVar{
+Name: "env_name",
+ValueFrom: &v1.EnvVarSource{
+FieldRef: &v1.ObjectFieldSelector{
+APIVersion: "v1",
+FieldPath: "metadata.labels['label1']",
+},
+},
+},
+},
 } {
 t.Run(tt.name, func(tc *testing.T) {
 mutateDownwardAPIField(tt.env, tt.pod)