Support custom resources with scale subresource in checkOwnerRef (#306)

Support custom resources with scale subresource in checkOwnerRef

The checkOwnerRef function was previously hardcoded to only accept
ReplicaSet and StatefulSet as valid owner references, preventing the
WPA from working with custom resources that implement the scale
subresource.

This change removes the kind restriction, allowing the WPA to autoscale
any resource type that implements the scale subresource (e.g., custom
controllers like EphemeraKV). The special handling for ReplicaSets
(stripping the generated suffix to match Deployment names) is preserved,
while all other resource kinds now match directly by name.

Changes:
- Remove kind restriction in checkOwnerRef() to support any owner reference
- Add test cases for custom resource types (EphemeraKV, CustomController)
- Maintain backward compatibility with Deployment and StatefulSet

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Co-authored-by: cedric.lamoriniere <[email protected]>

Author: clamoriniere

controllers/datadoghq/replica_calculator.go

@@ -557,18 +557,20 @@ const (
 
 func checkOwnerRef(ownerRef []metav1.OwnerReference, targetName string) bool {
 	for _, o := range ownerRef {
-		if o.Kind != replicaSetKind && o.Kind != statefulSetKind {
-			continue
-		}
-
 		mainOwnerRef := o.Name
+
+		// For ReplicaSets managed by Deployments, we need to strip the generated suffix
+		// to get the Deployment name (e.g., "myapp-7d8f9c5b6d" -> "myapp")
 		if o.Kind == replicaSetKind {
-			// removes the last section from the replicaSet name to get the deployment name.
 			lastIndex := strings.LastIndex(o.Name, "-")
 			if lastIndex > -1 {
 				mainOwnerRef = o.Name[:lastIndex]
 			}
 		}
+
+		// Check if the owner reference matches the target name
+		// This now supports any Kind that implements the scale subresource
+		// (Deployment, StatefulSet, custom resources, etc.)
 		if mainOwnerRef == targetName {
 			return true
 		}

controllers/datadoghq/replica_calculator_test.go

@@ -3245,6 +3245,45 @@ func Test_checkOwnerRef(t *testing.T) {
 			},
 			want: false,
 		},
+		{
+			name: "custom resource should match",
+			args: args{
+				ownerRef: []metav1.OwnerReference{
+					{
+						Kind: "EphemeraKV",
+						Name: "my-ephemera",
+					},
+				},
+				targetName: "my-ephemera",
+			},
+			want: true,
+		},
+		{
+			name: "custom resource should not match",
+			args: args{
+				ownerRef: []metav1.OwnerReference{
+					{
+						Kind: "EphemeraKV",
+						Name: "my-ephemera",
+					},
+				},
+				targetName: "other-ephemera",
+			},
+			want: false,
+		},
+		{
+			name: "any custom kind should match when name matches",
+			args: args{
+				ownerRef: []metav1.OwnerReference{
+					{
+						Kind: "CustomController",
+						Name: "test-resource",
+					},
+				},
+				targetName: "test-resource",
+			},
+			want: true,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {