feat: allow labels to be copied to delegate pods without prefix

pkg/common/constants.go

@@ -40,6 +40,10 @@ var (
 
 	AnnotationKeyUseConstraintsFromSpecForProxyPodScheduling = KeyPrefix + "use-constraints-from-spec-for-proxy-pod-scheduling"
 
+	// AnnotationKeyDelegateLabelKeysToSkipPrefixing defines label keys that won't get prefixed with KeyPrefix
+	// on the delegate pod and retain the original label key
+	AnnotationKeyDelegateLabelKeysToSkipPrefixing = KeyPrefix + "label-keys-to-skip-prefixing"
+
 	// annotations on proxy pods (by mutating admission webhook)
 
 	KeyPrefixSourcePod = KeyPrefix + "sourcepod-"

pkg/controllers/follow/service/controller.go

@@ -181,7 +181,7 @@ func (r reconciler) Handle(obj interface{}) (requeueAfter *time.Duration, err er
 			svcCopy.Annotations[common.AnnotationKeyOriginalSelector] = originalSelector
 		}
 		if r.serviceRerouteEnabled {
-			selector, changed := delegatepod.ChangeLabels(svcCopy.Spec.Selector)
+			selector, changed := delegatepod.ChangeLabels(svcCopy.Spec.Selector, svc.Annotations[common.AnnotationKeyDelegateLabelKeysToSkipPrefixing])
 			if changed {
 				needUpdateLocal = true
 				svcCopy.Spec.Selector = selector

pkg/model/delegatepod/model.go

@@ -17,6 +17,7 @@
 package delegatepod
 
 import (
+	"slices"
 	"strings"
 
 	corev1 "k8s.io/api/core/v1"
@@ -48,7 +49,7 @@ func MakeDelegatePod(proxyPod *corev1.Pod, clusterName string) (*v1alpha1.PodCha
 		}
 	}
 
-	labels, _ := ChangeLabels(srcPod.Labels)
+	labels, _ := ChangeLabels(srcPod.Labels, srcPod.Annotations[common.AnnotationKeyDelegateLabelKeysToSkipPrefixing])
 
 	delegatePod := &v1alpha1.PodChaperon{
 		ObjectMeta: metav1.ObjectMeta{
@@ -90,11 +91,17 @@ func MakeDelegatePod(proxyPod *corev1.Pod, clusterName string) (*v1alpha1.PodCha
 // The name segment is required and must be 63 characters or less"
 // https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set
 // TODO: resolve conflict two keys have same name but different prefixes
-func ChangeLabels(labels map[string]string) (map[string]string, bool) {
+func ChangeLabels(labels map[string]string, labelKeysToSkipPrefixing string) (map[string]string, bool) {
 	changed := false
 	newLabels := make(map[string]string)
+	labelKeysToSkip := strings.Split(labelKeysToSkipPrefixing, ",")
+
 	for k, v := range labels {
 		keySplit := strings.Split(k, "/") // note: assume no empty key (enforced by Kubernetes)
+		if slices.Contains(labelKeysToSkip, k) {
+			newLabels[k] = v
+			continue
+		}
 		if len(keySplit) == 1 || keySplit[0] != common.KeyPrefix {
 			changed = true
 			newKey := common.KeyPrefix + keySplit[len(keySplit)-1]

pkg/model/delegatepod/model_test.go

@@ -0,0 +1,71 @@
+/*
+ * Copyright The Multicluster-Scheduler Authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package delegatepod
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestChangeLabels(t *testing.T) {
+	tests := []struct {
+		name                     string
+		inputLabels              map[string]string
+		labelKeysToSkipPrefixing string
+		outputLabels             map[string]string
+	}{
+		{
+			name: "mix of domains, no skip",
+			inputLabels: map[string]string{
+				"foo.com/bar":                   "a",
+				"baz.com/foo":                   "b",
+				"multicluster.admiralty.io/baz": "c",
+				"a":                             "d",
+			},
+			labelKeysToSkipPrefixing: "",
+			outputLabels: map[string]string{
+				"multicluster.admiralty.io/bar": "a",
+				"multicluster.admiralty.io/foo": "b",
+				"multicluster.admiralty.io/baz": "c",
+				"multicluster.admiralty.io/a":   "d",
+			},
+		},
+		{
+			name: "skip multiple domains",
+			inputLabels: map[string]string{
+				"foo.com/bar":                   "a",
+				"baz.com/foo":                   "b",
+				"multicluster.admiralty.io/foo": "c",
+				"a":                             "d",
+			},
+			labelKeysToSkipPrefixing: "foo.com/bar,baz.com/foo",
+			outputLabels: map[string]string{
+				"foo.com/bar":                   "a",
+				"baz.com/foo":                   "b",
+				"multicluster.admiralty.io/foo": "c",
+				"multicluster.admiralty.io/a":   "d",
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			out, _ := ChangeLabels(tt.inputLabels, tt.labelKeysToSkipPrefixing)
+			require.Equal(t, tt.outputLabels, out)
+		})
+	}
+}