fix: should resolve SubNamespace conflict when sub-namespace deleted

cmd/accurate-controller/sub/run.go

@@ -133,6 +133,9 @@ func subMain(ns, addr string, port int) error {
 	hooks.SetupNamespaceWebhook(mgr, dec)
 
 	// SubNamespace reconciler & webhook
+	if err := indexing.SetupIndexForSubNamespace(ctx, mgr); err != nil {
+		return fmt.Errorf("failed to setup indexer for subnamespaces: %w", err)
+	}
 	if err = (&controllers.SubNamespaceReconciler{
 		Client: mgr.GetClient(),
 	}).SetupWithManager(mgr); err != nil {

controllers/subnamespace_controller.go

@@ -16,14 +16,15 @@ import (
 	"k8s.io/apimachinery/pkg/types"
 	metav1ac "k8s.io/client-go/applyconfigurations/meta/v1"
 	"k8s.io/client-go/util/csaupgrade"
-	"k8s.io/client-go/util/workqueue"
 	kstatus "sigs.k8s.io/cli-utils/pkg/kstatus/status"
 	ctrl "sigs.k8s.io/controller-runtime"
+	"sigs.k8s.io/controller-runtime/pkg/builder"
 	"sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"
 	"sigs.k8s.io/controller-runtime/pkg/event"
 	"sigs.k8s.io/controller-runtime/pkg/handler"
 	"sigs.k8s.io/controller-runtime/pkg/log"
+	"sigs.k8s.io/controller-runtime/pkg/predicate"
 	"sigs.k8s.io/controller-runtime/pkg/reconcile"
 )
 
@@ -154,30 +155,40 @@ func (r *SubNamespaceReconciler) reconcileNS(ctx context.Context, sn *accuratev2
 
 // SetupWithManager sets up the controller with the Manager.
 func (r *SubNamespaceReconciler) SetupWithManager(mgr ctrl.Manager) error {
-	nsHandler := func(o client.Object, q workqueue.RateLimitingInterface) {
+	nsHandler := func(ctx context.Context, o client.Object) (requests []reconcile.Request) {
 		parent := o.GetLabels()[constants.LabelParent]
-		if parent == "" {
+		if parent == "" && o.GetDeletionTimestamp() != nil {
+			// The namespace has no parent and is in terminating state,
+			// let's find all subnamespaces that might want to recreate it.
+			snList := &accuratev2.SubNamespaceList{}
+			err := r.List(ctx, snList, client.MatchingFields{constants.SubNamespaceNameKey: o.GetName()})
+			if err != nil {
+				logger := log.FromContext(ctx)
+				logger.Error(err, "failed to list subnamespaces")
+				return
+			}
+			for _, sn := range snList.Items {
+				requests = append(requests, reconcile.Request{NamespacedName: types.NamespacedName{
+					Namespace: sn.Namespace,
+					Name:      sn.Name,
+				}})
+			}
 			return
 		}
-		q.Add(reconcile.Request{NamespacedName: types.NamespacedName{
+		requests = append(requests, reconcile.Request{NamespacedName: types.NamespacedName{
 			Namespace: parent,
 			Name:      o.GetName(),
 		}})
+		return
 	}
 
 	return ctrl.NewControllerManagedBy(mgr).
 		For(&accuratev2.SubNamespace{}).
-		Watches(&corev1.Namespace{}, handler.Funcs{
-			UpdateFunc: func(ctx context.Context, ev event.UpdateEvent, q workqueue.RateLimitingInterface) {
-				if ev.ObjectNew.GetDeletionTimestamp() != nil {
-					return
-				}
-				nsHandler(ev.ObjectOld, q)
+		Watches(&corev1.Namespace{}, handler.EnqueueRequestsFromMapFunc(nsHandler), builder.WithPredicates(predicate.Funcs{
+			CreateFunc: func(e event.TypedCreateEvent[client.Object]) bool {
+				return false
 			},
-			DeleteFunc: func(ctx context.Context, ev event.DeleteEvent, q workqueue.RateLimitingInterface) {
-				nsHandler(ev.Object, q)
-			},
-		}).
+		})).
 		Complete(r)
 }
 

controllers/subnamespace_controller_test.go

@@ -6,6 +6,7 @@ import (
 
 	accuratev2 "github.com/cybozu-go/accurate/api/accurate/v2"
 	"github.com/cybozu-go/accurate/pkg/constants"
+	"github.com/cybozu-go/accurate/pkg/indexing"
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
 	corev1 "k8s.io/api/core/v1"
@@ -34,6 +35,9 @@ var _ = Describe("SubNamespace controller", func() {
 		err = snr.SetupWithManager(mgr)
 		Expect(err).ToNot(HaveOccurred())
 
+		err = indexing.SetupIndexForSubNamespace(ctx, mgr)
+		Expect(err).NotTo(HaveOccurred())
+
 		ctx, cancel := context.WithCancel(ctx)
 		stopFunc = cancel
 		go func() {
@@ -50,7 +54,7 @@ var _ = Describe("SubNamespace controller", func() {
 		time.Sleep(100 * time.Millisecond)
 	})
 
-	It("should create and delete sub namespaces", func() {
+	It("should create and delete sub-namespaces", func() {
 		ns := &corev1.Namespace{}
 		ns.Name = "test1"
 		Expect(k8sClient.Create(ctx, ns)).To(Succeed())
@@ -92,9 +96,14 @@ var _ = Describe("SubNamespace controller", func() {
 		Eventually(komega.Object(sn)).Should(HaveField("Status.ObservedGeneration", BeNumerically(">", 0)))
 		Expect(sn.Status.Conditions).To(HaveLen(1))
 		Expect(sn.Status.Conditions[0].Reason).To(Equal(accuratev2.SubNamespaceConflict))
+
+		// It's tempting to test if a conflict can be resolved by deleting the conflicting namespace,
+		// but this is currently not possible because EnvTest does not support namespace deletion.
+		// See https://github.com/kubernetes-sigs/controller-runtime/issues/880 for details.
+		// This feature should be tested in e2e-tests.
 	})
 
-	It("should not delete a conflicting sub namespace", func() {
+	It("should not delete a conflicting sub-namespace", func() {
 		ns := &corev1.Namespace{}
 		ns.Name = "test3"
 		Expect(k8sClient.Create(ctx, ns)).To(Succeed())
@@ -121,7 +130,7 @@ var _ = Describe("SubNamespace controller", func() {
 		Consistently(komega.Object(sub1)).Should(HaveField("DeletionTimestamp", BeNil()))
 	})
 
-	It("should re-create a subnamespace if it is deleted", func() {
+	It("should re-create a sub-namespace if it is deleted", func() {
 		ns := &corev1.Namespace{}
 		ns.Name = "test4"
 		Expect(k8sClient.Create(ctx, ns)).To(Succeed())

pkg/constants/indexer.go

@@ -5,4 +5,5 @@ const (
 	NamespaceParentKey   = "namespace.parent"
 	NamespaceTemplateKey = "namespace.template"
 	PropagateKey         = "resource.propagate"
+	SubNamespaceNameKey  = "subnamespace.name"
 )

pkg/indexing/indexing.go

@@ -3,6 +3,7 @@ package indexing
 import (
 	"context"
 
+	accuratev2 "github.com/cybozu-go/accurate/api/accurate/v2"
 	"github.com/cybozu-go/accurate/pkg/constants"
 	corev1 "k8s.io/api/core/v1"
 	"sigs.k8s.io/controller-runtime/pkg/client"
@@ -23,7 +24,7 @@ func SetupIndexForResource(ctx context.Context, mgr manager.Manager, res client.
 // SetupIndexForNamespace sets up indexers for namespaces.
 func SetupIndexForNamespace(ctx context.Context, mgr manager.Manager) error {
 	ns := &corev1.Namespace{}
-	err := mgr.GetFieldIndexer().IndexField(context.Background(), ns, constants.NamespaceParentKey, func(rawObj client.Object) []string {
+	err := mgr.GetFieldIndexer().IndexField(ctx, ns, constants.NamespaceParentKey, func(rawObj client.Object) []string {
 		parent := rawObj.GetLabels()[constants.LabelParent]
 		if parent == "" {
 			return nil
@@ -42,3 +43,10 @@ func SetupIndexForNamespace(ctx context.Context, mgr manager.Manager) error {
 		return []string{tmpl}
 	})
 }
+
+// SetupIndexForSubNamespace sets up indexers for subnamespaces.
+func SetupIndexForSubNamespace(ctx context.Context, mgr manager.Manager) error {
+	return mgr.GetFieldIndexer().IndexField(ctx, &accuratev2.SubNamespace{}, constants.SubNamespaceNameKey, func(rawObj client.Object) []string {
+		return []string{rawObj.GetName()}
+	})
+}