address comments

Author: Ryan Zhang

apis/placement/v1alpha1/common.go

@@ -19,9 +19,9 @@ const (
 	OverrideClusterNameVariable = "${MEMBER-CLUSTER-NAME}"
 
 	// OverrideClusterLabelKeyVariablePrefix is the reserved variable prefix in the override expression.
-	// The string will be replaced by the actual label value with the given the name of the key following the prefix.
-	// The key name ends with a "}" character.
-	// The key name has a maximum length of 63 characters and must be a valid label name.
-	// For example, if the key name is "region", the variable will be "${MEMBER-CLUSTER-LABEL-KEY-region}"
+	// The string will be replaced by the actual label value associated with the key following the prefix.
+	// The key name ends with a "}" character (but not include it).
+	// The key name must be a valid label name and case-sensitive.
+	// For example, if the key name is "kube-fleet.io/region", the variable will be "${MEMBER-CLUSTER-LABEL-KEY-kube-fleet.io/region}"
 	OverrideClusterLabelKeyVariablePrefix = "${MEMBER-CLUSTER-LABEL-KEY-"
 )

pkg/controllers/workgenerator/override.go

@@ -239,7 +239,7 @@ func applyJSONPatchOverride(resourceContent *placementv1beta1.ResourceContent, c
 // replaceClusterLabelKeyVariables finds all occurrences of the OverrideClusterLabelKeyVariablePrefix pattern
 // (e.g. ${MEMBER-CLUSTER-LABEL-KEY-region}) in the input string and replaces them with
 // the corresponding label values from the cluster.
-// If a label with the specified key doesn't exist, the variable remains unchanged.
+// If a label with the specified key doesn't exist, it returns an error.
 func replaceClusterLabelKeyVariables(input string, cluster *clusterv1beta1.MemberCluster) (string, error) {
 	prefixLen := len(placementv1alpha1.OverrideClusterLabelKeyVariablePrefix)
 	result := input

pkg/controllers/workgenerator/override_test.go

@@ -2760,7 +2760,7 @@ func TestApplyJSONPatchOverride(t *testing.T) {
 	}
 }
 
-func Test_replaceClusterLabelKeyVariables(t *testing.T) {
+func TestReplaceClusterLabelKeyVariables(t *testing.T) {
 	tests := map[string]struct {
 		cluster   *clusterv1beta1.MemberCluster
 		input     string
@@ -2819,6 +2819,17 @@ func Test_replaceClusterLabelKeyVariables(t *testing.T) {
 			input:     "The cluster is in ${MEMBER-CLUSTER-LABEL-KEY-region}",
 			expectErr: true,
 		},
+		"ClusterLabelKey Variable key case not match": {
+			cluster: &clusterv1beta1.MemberCluster{
+				ObjectMeta: metav1.ObjectMeta{
+					Labels: map[string]string{
+						"region": "us-west-1",
+					},
+				},
+			},
+			input:     "The cluster is in ${MEMBER-CLUSTER-LABEL-KEY-REGION}",
+			expectErr: true,
+		},
 		"Invalid  clusterLabelKey variable format": {
 			cluster: &clusterv1beta1.MemberCluster{
 				ObjectMeta: metav1.ObjectMeta{
@@ -2830,6 +2841,17 @@ func Test_replaceClusterLabelKeyVariables(t *testing.T) {
 			input:     "The cluster is in ${MEMBER-CLUSTER-LABEL-KEY-region",
 			expectErr: true,
 		},
+		"ClusterLabelKey variable key empty": {
+			cluster: &clusterv1beta1.MemberCluster{
+				ObjectMeta: metav1.ObjectMeta{
+					Labels: map[string]string{
+						"region": "us-west-1",
+					},
+				},
+			},
+			input:     "The cluster is in ${MEMBER-CLUSTER-LABEL-KEY-}",
+			expectErr: true,
+		},
 	}
 
 	for name, tc := range tests {