StaticResourceController: Avoid adding the same informer more than once

Adding the same informer several times is useless and has a negative side-effect: a change of object on API-server leads to scheduling reconcile loop several times. Calling reconcile more often than necessary is not great.

Author: mpatlasov

pkg/operator/staticresourcecontroller/static_resource_controller.go

@@ -26,6 +26,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime/serializer"
 	utilerrors "k8s.io/apimachinery/pkg/util/errors"
 	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
+	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/client-go/informers"
 	"k8s.io/client-go/tools/cache"
 	"k8s.io/klog/v2"
@@ -187,6 +188,9 @@ func (c *StaticResourceController) AddKubeInformers(kubeInformersByNamespace v1h
 	// set the informers so we can have caching clients
 	c.clients = c.clients.WithKubernetesInformers(kubeInformersByNamespace)
 
+	// avoid adding an informer more than once
+	informerSet := sets.New[cache.SharedIndexInformer]()
+
 	ret := c
 	for _, conditionalManifest := range c.manifests {
 		for _, file := range conditionalManifest.files {
@@ -227,29 +231,29 @@ func (c *StaticResourceController) AddKubeInformers(kubeInformersByNamespace v1h
 			case *corev1.Namespace:
 				ret = ret.AddNamespaceInformer(informer.Core().V1().Namespaces().Informer(), t.Name)
 			case *corev1.Service:
-				ret = ret.AddInformer(informer.Core().V1().Services().Informer())
+				ret = ret.AddInformer(informerSet, informer.Core().V1().Services().Informer())
 			case *corev1.Pod:
-				ret = ret.AddInformer(informer.Core().V1().Pods().Informer())
+				ret = ret.AddInformer(informerSet, informer.Core().V1().Pods().Informer())
 			case *corev1.ServiceAccount:
-				ret = ret.AddInformer(informer.Core().V1().ServiceAccounts().Informer())
+				ret = ret.AddInformer(informerSet, informer.Core().V1().ServiceAccounts().Informer())
 			case *corev1.ConfigMap:
-				ret = ret.AddInformer(informer.Core().V1().ConfigMaps().Informer())
+				ret = ret.AddInformer(informerSet, informer.Core().V1().ConfigMaps().Informer())
 			case *corev1.Secret:
-				ret = ret.AddInformer(informer.Core().V1().Secrets().Informer())
+				ret = ret.AddInformer(informerSet, informer.Core().V1().Secrets().Informer())
 			case *rbacv1.ClusterRole:
-				ret = ret.AddInformer(informer.Rbac().V1().ClusterRoles().Informer())
+				ret = ret.AddInformer(informerSet, informer.Rbac().V1().ClusterRoles().Informer())
 			case *rbacv1.ClusterRoleBinding:
-				ret = ret.AddInformer(informer.Rbac().V1().ClusterRoleBindings().Informer())
+				ret = ret.AddInformer(informerSet, informer.Rbac().V1().ClusterRoleBindings().Informer())
 			case *rbacv1.Role:
-				ret = ret.AddInformer(informer.Rbac().V1().Roles().Informer())
+				ret = ret.AddInformer(informerSet, informer.Rbac().V1().Roles().Informer())
 			case *rbacv1.RoleBinding:
-				ret = ret.AddInformer(informer.Rbac().V1().RoleBindings().Informer())
+				ret = ret.AddInformer(informerSet, informer.Rbac().V1().RoleBindings().Informer())
 			case *policyv1.PodDisruptionBudget:
-				ret = ret.AddInformer(informer.Policy().V1().PodDisruptionBudgets().Informer())
+				ret = ret.AddInformer(informerSet, informer.Policy().V1().PodDisruptionBudgets().Informer())
 			case *storagev1.StorageClass:
-				ret = ret.AddInformer(informer.Storage().V1().StorageClasses().Informer())
+				ret = ret.AddInformer(informerSet, informer.Storage().V1().StorageClasses().Informer())
 			case *storagev1.CSIDriver:
-				ret = ret.AddInformer(informer.Storage().V1().CSIDrivers().Informer())
+				ret = ret.AddInformer(informerSet, informer.Storage().V1().CSIDrivers().Informer())
 			default:
 				// if there's a missing case, the caller can add an informer or count on a time based trigger.
 				// if the controller doesn't handle it, then there will be failure from the underlying apply.
@@ -261,8 +265,11 @@ func (c *StaticResourceController) AddKubeInformers(kubeInformersByNamespace v1h
 	return ret
 }
 
-func (c *StaticResourceController) AddInformer(informer cache.SharedIndexInformer) *StaticResourceController {
-	c.factory.WithInformers(informer)
+func (c *StaticResourceController) AddInformer(set sets.Set[cache.SharedIndexInformer], informer cache.SharedIndexInformer) *StaticResourceController {
+	if !set.Has(informer) {
+		sets.Insert(set, informer)
+		c.factory.WithInformers(informer)
+	}
 	return c
 }