feat: add annotations to skip target and weight reconciliation for externally-managed resources

apis/v1alpha1/ack-generate-metadata.yaml

@@ -1,13 +1,13 @@
 ack_generate_info:
-  build_date: "2026-05-30T22:41:57Z"
-  build_hash: a307e8ebd9503616baf5915c744a30dc3aa227c5
-  go_version: go1.26.3
-  version: v0.59.1-4-ga307e8e
+  build_date: "2026-06-12T02:08:23Z"
+  build_hash: 2970ca9b3789515150e27ab80630175a8c77cba4
+  go_version: go1.26.4
+  version: v0.59.1-7-g2970ca9
 api_directory_checksum: 060554dd6962e2466013922cf96fb4cf92a23706
 api_version: v1alpha1
 aws_sdk_go_version: v1.32.6
 generator_config_info:
-  file_checksum: ce1168f649f03d9652bc8e82f8322d6dd2d909f0
+  file_checksum: bac271c7c08e6fc537c9665c20dbf2e37270ddd3
   original_file_name: generator.yaml
 last_modification:
   reason: API generation

apis/v1alpha1/generator.yaml

@@ -165,6 +165,8 @@ resources:
     tags:
       ignore: true
     hooks:
+      delta_pre_compare:
+        code: customPreCompare(delta, a, b)
       sdk_read_many_post_build_request:
         template_path: hooks/listener/sdk_read_many_post_build_request.go.tpl
   TargetGroup:

generator.yaml

@@ -165,6 +165,8 @@ resources:
     tags:
       ignore: true
     hooks:
+      delta_pre_compare:
+        code: customPreCompare(delta, a, b)
       sdk_read_many_post_build_request:
         template_path: hooks/listener/sdk_read_many_post_build_request.go.tpl
   TargetGroup:

pkg/resource/listener/hooks.go

@@ -1,5 +1,17 @@
 package listener
 
+import (
+	ackcompare "github.com/aws-controllers-k8s/runtime/pkg/compare"
+)
+
+const (
+	// AnnotationWeightManagement controls how the controller manages forward
+	// action weights for target groups. When set to "ignore", the controller
+	// will not reconcile weight differences — allowing an external controller
+	// or deployment tool to manage blue/green traffic shifting independently.
+	AnnotationWeightManagement = "elbv2.services.k8s.aws/weight-management"
+)
+
 // customCheckRequiredFieldsMissingMethod returns true if there are any fields
 // for the ReadOne Input shape that are required but not present in the
 // resource's Spec or Status.
@@ -8,3 +20,65 @@ func (rm *resourceManager) customCheckRequiredFieldsMissingMethod(
 ) bool {
 	return r.Identifiers().ARN() == nil
 }
+
+// customPreCompare is the delta_pre_compare hook. When weight management is
+// ignored, it copies the AWS-side weights into the desired spec so that the
+// DeepEqual comparison on DefaultActions does not flag external weight
+// changes as drift.
+func customPreCompare(
+	delta *ackcompare.Delta,
+	a *resource,
+	b *resource,
+) {
+	if isWeightManagementIgnored(a) {
+		mergeLatestWeights(a, b)
+	}
+}
+
+// isWeightManagementIgnored returns true if the resource has the
+// AnnotationWeightManagement annotation set to "ignore", indicating that
+// target group weights should be managed by an external controller.
+func isWeightManagementIgnored(r *resource) bool {
+	if r == nil || r.ko == nil {
+		return false
+	}
+	annotations := r.ko.GetAnnotations()
+	if annotations == nil {
+		return false
+	}
+	return annotations[AnnotationWeightManagement] == "ignore"
+}
+
+// mergeLatestWeights copies the TargetGroup weights from the latest (AWS)
+// state into the desired resource. This prevents external weight changes
+// from being detected as drift and from being overwritten during updates.
+func mergeLatestWeights(desired, latest *resource) {
+	if latest == nil || latest.ko == nil || desired == nil || desired.ko == nil {
+		return
+	}
+	// Build a map from TargetGroupARN to Weight from the latest (AWS) state
+	latestWeights := map[string]*int64{}
+	for _, action := range latest.ko.Spec.DefaultActions {
+		if action != nil && action.ForwardConfig != nil {
+			for _, tg := range action.ForwardConfig.TargetGroups {
+				if tg.TargetGroupARN != nil {
+					latestWeights[*tg.TargetGroupARN] = tg.Weight
+				}
+			}
+		}
+	}
+
+	// Overwrite desired weights with latest weights for any target group
+	// that exists in both desired and latest.
+	for _, action := range desired.ko.Spec.DefaultActions {
+		if action != nil && action.ForwardConfig != nil {
+			for _, tg := range action.ForwardConfig.TargetGroups {
+				if tg.TargetGroupARN != nil {
+					if w, ok := latestWeights[*tg.TargetGroupARN]; ok {
+						tg.Weight = w
+					}
+				}
+			}
+		}
+	}
+}