Optimize ManagedClusterAddOn event handling in addon template controller

Replace filtered event handling with custom event handlers that only trigger
reconciliation when AddOnTemplate configReferences actually change. This
reduces unnecessary reconciliation cycles by using reflect.DeepEqual to
compare config references between old and new objects.

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

Co-Authored-By: Claude <[email protected]>
Signed-off-by: zhujian <[email protected]>

Author: zhujian7

pkg/addon/controllers/addontemplate/controller.go

@@ -2,6 +2,7 @@ package addontemplate
 
 import (
 	"context"
+	"reflect"
 	"time"
 
 	"github.com/openshift/library-go/pkg/controller/factory"
@@ -14,6 +15,7 @@ import (
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/rest"
 	"k8s.io/client-go/tools/cache"
+	"k8s.io/client-go/util/workqueue"
 	"k8s.io/klog/v2"
 
 	"open-cluster-management.io/addon-framework/pkg/addonfactory"
@@ -52,6 +54,7 @@ type addonTemplateController struct {
 	workInformers              workv1informers.SharedInformerFactory
 	runControllerFunc          runController
 	eventRecorder              events.Recorder
+	queue                      workqueue.RateLimitingInterface
 }
 
 type runController func(ctx context.Context, addonName string) error
@@ -69,6 +72,9 @@ func NewAddonTemplateController(
 	recorder events.Recorder,
 	runController ...runController,
 ) factory.Controller {
+	controllerName := "addon-template-controller"
+	syncCtx := factory.NewSyncContext(controllerName, recorder)
+
 	c := &addonTemplateController{
 		kubeConfig:                 hubKubeconfig,
 		kubeClient:                 hubKubeClient,
@@ -82,6 +88,7 @@ func NewAddonTemplateController(
 		dynamicInformers:           dynamicInformers,
 		workInformers:              workInformers,
 		eventRecorder:              recorder,
+		queue:                      syncCtx.Queue(),
 	}
 
 	if len(runController) > 0 {
@@ -90,35 +97,70 @@ func NewAddonTemplateController(
 		// easy to mock in unit tests
 		c.runControllerFunc = c.runController
 	}
-	return factory.New().
+
+	controller := factory.New().
+		WithSyncContext(syncCtx).
 		WithInformersQueueKeysFunc(
 			queue.QueueKeyByMetaNamespaceName,
 			addonInformers.Addon().V1alpha1().ClusterManagementAddOns().Informer()).
-		WithFilteredEventsInformersQueueKeysFunc(
-			queue.QueueKeyByMetaName,
-			func(obj interface{}) bool {
-				mca, ok := obj.(*addonv1alpha1.ManagedClusterAddOn)
-				if !ok {
-					return false
-				}
-
-				// Only process ManagedClusterAddOns that reference AddOnTemplates
-				for _, configRef := range mca.Status.ConfigReferences {
-					if configRef.ConfigGroupResource.Group == "addon.open-cluster-management.io" &&
-						configRef.ConfigGroupResource.Resource == "addontemplates" {
-						return true
-					}
-				}
-				return false
-			},
-			addonInformers.Addon().V1alpha1().ManagedClusterAddOns().Informer()).
 		WithBareInformers(
+			addonInformers.Addon().V1alpha1().ManagedClusterAddOns().Informer(),
 			// do not need to queue, just make sure the controller reconciles after the addonTemplate cache is synced
 			// otherwise, there will be "xx-addon-template" not found" errors in the log as the controller uses the
 			// addonTemplate lister to get the template object
 			addonInformers.Addon().V1alpha1().AddOnTemplates().Informer()).
 		WithSync(c.sync).
 		ToController("addon-template-controller", recorder)
+
+	// Add custom event handler for ManagedClusterAddon to filter configReference changes
+	// following the pattern from managedClusterSetController
+	_, err := addonInformers.Addon().V1alpha1().ManagedClusterAddOns().Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
+		UpdateFunc: func(oldObj, newObj interface{}) {
+			// Only handle configReference updates for AddOnTemplates
+			oldMCA, ok := oldObj.(*addonv1alpha1.ManagedClusterAddOn)
+			if !ok {
+				return
+			}
+			newMCA, ok := newObj.(*addonv1alpha1.ManagedClusterAddOn)
+			if !ok {
+				return
+			}
+
+			// Extract AddOnTemplate configReferences from both old and new
+			oldTemplateRefs := extractAddOnTemplateConfigRefs(oldMCA)
+			newTemplateRefs := extractAddOnTemplateConfigRefs(newMCA)
+
+			// Only process if AddOnTemplate configReferences changed
+			if !reflect.DeepEqual(oldTemplateRefs, newTemplateRefs) {
+				// Queue the addon name to trigger reconciliation
+				c.queue.Add(newMCA.Name)
+			}
+		},
+		DeleteFunc: func(obj interface{}) {
+			mca, ok := obj.(*addonv1alpha1.ManagedClusterAddOn)
+			if !ok {
+				return
+			}
+			c.queue.Add(mca.Name)
+		},
+	})
+	if err != nil {
+		utilruntime.HandleError(err)
+	}
+
+	return controller
+}
+
+// extractAddOnTemplateConfigRefs extracts only AddOnTemplate configReferences
+func extractAddOnTemplateConfigRefs(mca *addonv1alpha1.ManagedClusterAddOn) []addonv1alpha1.ConfigReference {
+	var templateRefs []addonv1alpha1.ConfigReference
+	for _, configRef := range mca.Status.ConfigReferences {
+		if configRef.ConfigGroupResource.Group == "addon.open-cluster-management.io" &&
+			configRef.ConfigGroupResource.Resource == "addontemplates" {
+			templateRefs = append(templateRefs, configRef)
+		}
+	}
+	return templateRefs
 }
 
 func (c *addonTemplateController) stopUnusedManagers(