Add WithClusterNotFoundWrapper to controller builder

On-behalf-of: SAP <[email protected]>
Signed-off-by: Marvin Beckers <[email protected]>

Author: embik

examples/cluster-api/main.go

@@ -40,7 +40,6 @@ import (
 
 	mcbuilder "sigs.k8s.io/multicluster-runtime/pkg/builder"
 	mcmanager "sigs.k8s.io/multicluster-runtime/pkg/manager"
-	"sigs.k8s.io/multicluster-runtime/pkg/multicluster"
 	mcreconcile "sigs.k8s.io/multicluster-runtime/pkg/reconcile"
 	capi "sigs.k8s.io/multicluster-runtime/providers/cluster-api"
 )
@@ -104,10 +103,6 @@ func main() {
 
 				cl, err := mcMgr.GetCluster(ctx, req.ClusterName)
 				if err != nil {
-					if errors.Is(err, multicluster.ErrClusterNotFound) {
-						log.Info("Cluster not found, might have been disengaged")
-						return reconcile.Result{}, nil
-					}
 					return reconcile.Result{}, err
 				}
 

examples/kind/main.go

@@ -35,7 +35,6 @@ import (
 
 	mcbuilder "sigs.k8s.io/multicluster-runtime/pkg/builder"
 	mcmanager "sigs.k8s.io/multicluster-runtime/pkg/manager"
-	"sigs.k8s.io/multicluster-runtime/pkg/multicluster"
 	mcreconcile "sigs.k8s.io/multicluster-runtime/pkg/reconcile"
 	"sigs.k8s.io/multicluster-runtime/providers/kind"
 )
@@ -62,10 +61,7 @@ func main() {
 
 				cl, err := mgr.GetCluster(ctx, req.ClusterName)
 				if err != nil {
-					if errors.Is(err, multicluster.ErrClusterNotFound) {
-						log.Info("Cluster not found, might have been disengaged")
-						return reconcile.Result{}, nil
-					}
+					return reconcile.Result{}, err
 				}
 
 				cm := &corev1.ConfigMap{}

examples/namespace/main.go

@@ -43,7 +43,6 @@ import (
 
 	mcbuilder "sigs.k8s.io/multicluster-runtime/pkg/builder"
 	mcmanager "sigs.k8s.io/multicluster-runtime/pkg/manager"
-	"sigs.k8s.io/multicluster-runtime/pkg/multicluster"
 	mcreconcile "sigs.k8s.io/multicluster-runtime/pkg/reconcile"
 	"sigs.k8s.io/multicluster-runtime/providers/namespace"
 )
@@ -128,10 +127,6 @@ func main() {
 
 				cl, err := mgr.GetCluster(ctx, req.ClusterName)
 				if err != nil {
-					if errors.Is(err, multicluster.ErrClusterNotFound) {
-						log.Info("Cluster not found, might have been disengaged")
-						return reconcile.Result{}, nil
-					}
 					return reconcile.Result{}, err
 				}
 

pkg/builder/forked_controller.go

@@ -73,6 +73,8 @@ type TypedBuilder[request mcreconcile.ClusterAware[request]] struct {
 	ctrlOptions      controller.TypedOptions[request]
 	name             string
 	newController    func(name string, mgr mcmanager.Manager, options controller.TypedOptions[request]) (mccontroller.TypedController[request], error)
+
+	enableClusterNotFoundWrapper *bool
 }
 
 // ControllerManagedBy returns a new controller builder that will be started by the provided Manager.
@@ -260,6 +262,15 @@ func (blder *TypedBuilder[request]) WithLogConstructor(logConstructor func(*requ
 	return blder
 }
 
+// WithClusterNotFoundWrapper enables or disables a reconciler that is wrapped around the original reconciler
+// added to this builder. [reconcile.ClusterNotFoundWrapper] will stop reconcile results with [multicluster.ErrClusterNotFound]
+// as error from requeuing by marking them as successfully reconciled. This wrapper is enabled by default
+// and can be disabled with this builder method by setting it to false.
+func (blder *TypedBuilder[request]) WithClusterNotFoundWrapper(enabled bool) *TypedBuilder[request] {
+	blder.enableClusterNotFoundWrapper = ptr.To(enabled)
+	return blder
+}
+
 // Named sets the name of the controller to the given name. The name shows up
 // in metrics, among other things, and thus should be a prometheus compatible name
 // (underscores and alphanumeric characters only).
@@ -450,6 +461,11 @@ func (blder *TypedBuilder[request]) doController(r reconcile.TypedReconciler[req
 		ctrlOptions.Reconciler = r
 	}
 
+	// the ClusterNotFound wrapper is enabled by default, but can be disabled with WithClusterNotFoundWrapper(false).
+	if ptr.Deref(blder.enableClusterNotFoundWrapper, true) {
+		ctrlOptions.Reconciler = mcreconcile.NewClusterNotFoundWrapper(ctrlOptions.Reconciler)
+	}
+
 	// Retrieve the GVK from the object we're reconciling
 	// to pre-populate logger information, and to optionally generate a default name.
 	var gvk schema.GroupVersionKind

pkg/reconcile/wrapper.go

@@ -0,0 +1,54 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package reconcile
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"sigs.k8s.io/controller-runtime/pkg/reconcile"
+
+	"sigs.k8s.io/multicluster-runtime/pkg/multicluster"
+)
+
+// ClusterNotFoundWrapper wraps an existing [reconcile.TypedReconciler] and ignores [multicluster.ErrClusterNotFound] errors.
+type ClusterNotFoundWrapper[request comparable] struct {
+	wrapped reconcile.TypedReconciler[request]
+}
+
+// NewClusterNotFoundWrapper creates a new [ClusterNotFoundWrapper].
+func NewClusterNotFoundWrapper[request comparable](w reconcile.TypedReconciler[request]) reconcile.TypedReconciler[request] {
+	return &ClusterNotFoundWrapper[request]{wrapped: w}
+}
+
+// Reconcile implements [reconcile.TypedReconciler].
+func (r *ClusterNotFoundWrapper[request]) Reconcile(ctx context.Context, req request) (reconcile.Result, error) {
+	res, err := r.wrapped.Reconcile(ctx, req)
+
+	// if the error returned by the reconciler is ErrClusterNotFound, we return without requeuing.
+	if errors.Is(err, multicluster.ErrClusterNotFound) {
+		return reconcile.Result{}, nil
+	}
+
+	return res, err
+}
+
+// String returns a string representation of the wrapped reconciler.
+func (r *ClusterNotFoundWrapper[request]) String() string {
+	return fmt.Sprintf("%v", r.wrapped)
+}