fix(namespace): executor/router/buildermgr RemoveNamespace + per-NS informer lifecycle

- Add RemoveNamespace(ctx, ns) to executortype.ExecutorType interface
- Implement RemoveNamespace in poolmgr, newdeploy, container executor types
- Add per-namespace context cancellation (nsCancels map) in all three types so
  informer factories are stopped when namespace is removed (fixes goroutine leak)
- Add PoolPodController.RemoveNamespace to clear envLister/podLister maps
- Add deregisterNamespace() in executor multitenant subscriber
- Switch executor/router/buildermgr watcher strategy from TrackOnly to DispatchRemove
  so RemoveFunc is called when fission.io/managed label is removed
- Add RemoveFunc to executor/router/buildermgr namespace subscribers
- Add RemoveNamespace to environmentWatcher and packageWatcher with per-NS cancel
- Add RemoveNamespace to HTTPTriggerSet: cancels informers, removes from maps, calls syncTriggers
- Fix ns_watcher_test.go fakeExecutorType to implement new RemoveNamespace method

Fixes:
- Executor dedup gap: re-added namespace was silently skipped (envLister/deplLister still present)
- Goroutine/FD leak: old informer factories ran forever after namespace removal
- Router stale routes: HTTPTriggers for removed namespace stayed in routing table

doc/console-compat-2026-05-15.md

@@ -0,0 +1,72 @@
+# Console ↔ fission-src multitenant: compatibility check (2026-05-15)
+
+## Что изменилось в fission-src (feature/multitenant)
+
+| Изменение | Файл |
+|---|---|
+| Удалён старый partial RBAC | `deploy/executor-ns-watcher-rbac.yaml` |
+| Добавлен полный RBAC для NSWatcher | `deploy/multitenant/rbac.yaml` |
+| Добавлен `EnsureNamespaceSA` | `pkg/utils/serviceaccount.go` |
+| NSWatcher вызывает `EnsureNamespaceSA` при обнаружении NS с `fission.io/managed=true` | `pkg/executor/multitenant/ns_watcher.go` |
+| Добавлен тест NSWatcher с fake k8s | `pkg/utils/namespace_manager_test.go` |
+
+---
+
+## Что делает консоль при создании namespace
+
+`SetupFissionNamespace` в `console/internal/fission/namespace.go`:
+
+1. Создаёт Namespace с лейблами:
+   - `managed-by=fission-console`
+   - `fission.io/managed=true` ← триггер для NSWatcher
+
+2. Создаёт ServiceAccounts: `fission-fetcher`, `fission-builder`
+
+3. Создаёт RoleBindings с `cluster-admin` ClusterRole для всех Fission SA:
+   - `fission-executor`, `fission-router`, `fission-buildermgr`, `fission-kubewatcher`, `fission-timer`
+   - `fission-fetcher` (из fission NS + локально в user NS)
+   - `fission-builder` (из fission NS + локально в user NS)
+
+---
+
+## Взаимодействие с EnsureNamespaceSA
+
+`EnsureNamespaceSA` вызывается NSWatcher **после** того как консоль создала NS.
+Логика (в `setupSAAndRoleBindings`):
+
+1. Создаёт/получает SA `fission-fetcher` → SA уже существует → `IsAlreadyExists` → OK
+2. Для каждого permission из `fetcherCheck` вызывает `checkPermission` через `localsubjectaccessreviews`
+3. Поскольку у `fission-fetcher` уже есть `cluster-admin` RoleBinding (создан консолью) →
+   **все проверки возвращают `exists=true`** → `rules` остаётся пустым → Role и RoleBinding **не создаются**
+
+**Итог: EnsureNamespaceSA является no-op если консоль уже настроила namespace. Никаких конфликтов.**
+
+---
+
+## Что нужно на кластере
+
+Для работы NSWatcher нужен `deploy/multitenant/rbac.yaml` применён **один раз**:
+```bash
+kubectl apply -f ~/terra/fission-src/deploy/multitenant/rbac.yaml
+```
+
+Это даёт:
+- `fission-executor` → `list/watch namespaces` (NSWatcher)
+- `fission-router` → `list/watch namespaces` (NSWatcher)
+- `fission-executor` → `create SA/Role/RoleBinding` в user NS (`fission-executor-sa-provisioner`)
+
+Без этого RBAC `EnsureNamespaceSA` будет падать с Forbidden, но **консоль продолжит работать** — она создаёт SA/RoleBindings сама и не зависит от NSWatcher.
+
+---
+
+## Вердикт
+
+| Сценарий | Статус |
+|---|---|
+| Новый NS создаётся через консоль | ✅ работает как раньше |
+| NSWatcher обнаруживает NS по `fission.io/managed=true` | ✅ совместимо |
+| `EnsureNamespaceSA` вызывается в уже настроенном NS | ✅ no-op, нет конфликтов |
+| Старый NS (без нового fission-bundle) | ✅ консоль не зависит от NSWatcher |
+| Сборка консоли (`go build ./...`) | ✅ BUILD OK |
+
+**Код консоли менять не нужно.** Нужно только применить `deploy/multitenant/rbac.yaml` при деплое нового fission-bundle.

pkg/buildermgr/envwatcher.go

@@ -76,6 +76,8 @@ type (
 		podSpecPatch           *apiv1.PodSpec
 		envWatchInformer       map[string]k8sCache.SharedIndexInformer
 		enableOwnerReferences  bool
+		// nsCancels holds per-namespace context cancel functions.
+		nsCancels map[string]context.CancelFunc
 	}
 )
 
@@ -111,8 +113,8 @@ func makeEnvironmentWatcher(
 		podSpecPatch:           podSpecPatch,
 		envWatchInformer:       utils.GetInformersForNamespaces(fissionClient, time.Minute*30, fv1.EnvironmentResource),
 		enableOwnerReferences:  utils.IsOwnerReferencesEnabled(),
+		nsCancels:              make(map[string]context.CancelFunc),
 	}
-
 	err := envWatcher.EnvWatchEventHandlers(ctx)
 	if err != nil {
 		return nil, err
@@ -540,6 +542,21 @@ func (envw *environmentWatcher) AddNamespace(ctx context.Context, ns string, mgr
 
 	envw.envWatchInformer[ns] = envInf
 	mgr.AddInformers(ctx, map[string]k8sCache.SharedIndexInformer{ns: envInf})
-	factory.Start(ctx.Done())
+
+	// Create a per-namespace cancellable context for informer lifecycle.
+	nsCtx, nsCancel := context.WithCancel(ctx)
+	envw.nsCancels[ns] = nsCancel
+
+	factory.Start(nsCtx.Done())
 	envw.logger.Info("buildermgr.envWatcher.AddNamespace: done", zap.String("namespace", ns))
 }
+
+// RemoveNamespace deregisters a namespace from the environment watcher.
+func (envw *environmentWatcher) RemoveNamespace(ns string) {
+	if cancel, ok := envw.nsCancels[ns]; ok {
+		cancel()
+		delete(envw.nsCancels, ns)
+	}
+	delete(envw.envWatchInformer, ns)
+	envw.logger.Info("buildermgr.envWatcher.RemoveNamespace: cleaned up", zap.String("namespace", ns))
+}

pkg/buildermgr/namespace_subscriber.go

@@ -11,10 +11,18 @@ type builderEnvNamespaceAdder interface {
 	AddNamespace(ctx context.Context, ns string, mgr manager.Interface)
 }
 
+type builderEnvNamespaceRemover interface {
+	RemoveNamespace(ns string)
+}
+
 type builderPkgNamespaceAdder interface {
 	AddNamespace(ctx context.Context, ns string, mgr manager.Interface)
 }
 
+type builderPkgNamespaceRemover interface {
+	RemoveNamespace(ns string)
+}
+
 func NewNamespaceSubscriber(envw builderEnvNamespaceAdder, pkgw builderPkgNamespaceAdder, mgr manager.Interface) utils.NamespaceSubscriber {
 	return utils.NamespaceSubscriberFuncs{
 		SubscriberName: "buildermgr",
@@ -22,6 +30,10 @@ func NewNamespaceSubscriber(envw builderEnvNamespaceAdder, pkgw builderPkgNamesp
 			registerBuilderNamespace(ctx, record.Name, envw, pkgw, mgr)
 			return nil
 		},
+		RemoveFunc: func(ctx context.Context, record utils.NamespaceRecord) error {
+			deregisterBuilderNamespace(record.Name, envw, pkgw)
+			return nil
+		},
 		ResyncFunc: func(ctx context.Context, record utils.NamespaceRecord) error {
 			registerBuilderNamespace(ctx, record.Name, envw, pkgw, mgr)
 			return nil
@@ -41,3 +53,16 @@ func registerBuilderNamespace(ctx context.Context, namespace string, envw builde
 		pkgw.AddNamespace(ctx, namespace, mgr)
 	}
 }
+
+func deregisterBuilderNamespace(namespace string, envw builderEnvNamespaceAdder, pkgw builderPkgNamespaceAdder) {
+	if namespace == "" {
+		return
+	}
+	utils.DefaultNSResolver().RemoveNamespace(namespace)
+	if r, ok := envw.(builderEnvNamespaceRemover); ok {
+		r.RemoveNamespace(namespace)
+	}
+	if r, ok := pkgw.(builderPkgNamespaceRemover); ok {
+		r.RemoveNamespace(namespace)
+	}
+}

pkg/buildermgr/ns_watcher.go

@@ -25,7 +25,9 @@ func StartNSWatcher(
 	pkgw *packageWatcher,
 	mgr manager.Interface,
 ) {
-	_, err := utils.RunManagedNamespaceWatcher(ctx, logger, kubeClient, mgr, utils.NewDefaultManagedNamespaceWatcherConfig("buildermgr.NSWatcher", NewNamespaceSubscriber(envw, pkgw, mgr)))
+	config := utils.NewDefaultManagedNamespaceWatcherConfig("buildermgr.NSWatcher", NewNamespaceSubscriber(envw, pkgw, mgr))
+	config.RemovalStrategy = utils.NamespaceRemovalStrategyDispatchRemove
+	_, err := utils.RunManagedNamespaceWatcher(ctx, logger, kubeClient, mgr, config)
 	if err != nil {
 		logger.Error("buildermgr.NSWatcher: BootstrapAndDispatch failed", zap.Error(err))
 	}

pkg/buildermgr/pkgwatcher.go

@@ -49,6 +49,8 @@ type (
 		pkgInformer   map[string]k8sCache.SharedIndexInformer
 		storageSvcUrl string
 		buildCache    *cache.Cache[crd.CacheKeyUR, *fv1.Package]
+		// nsCancels holds per-namespace context cancel functions.
+		nsCancels map[string]context.CancelFunc
 	}
 )
 
@@ -64,6 +66,7 @@ func makePackageWatcher(logger *zap.Logger, fissionClient versioned.Interface, k
 		pkgInformer:   pkgInformer,
 		storageSvcUrl: storageSvcUrl,
 		buildCache:    cache.MakeCache[crd.CacheKeyUR, *fv1.Package](0, 0),
+		nsCancels:     make(map[string]context.CancelFunc),
 	}
 	return pkgw
 }
@@ -363,7 +366,23 @@ func (pkgw *packageWatcher) AddNamespace(ctx context.Context, ns string, mgr man
 		ns + "/pkg": pkgInf,
 		ns + "/pod": podInf,
 	})
-	fissionFactory.Start(ctx.Done())
+
-	podFactory.Start(ctx.Done())
+	// Create a per-namespace cancellable context for informer lifecycle.
+	nsCtx, nsCancel := context.WithCancel(ctx)
+	pkgw.nsCancels[ns] = nsCancel
+
+	fissionFactory.Start(nsCtx.Done())
+	podFactory.Start(nsCtx.Done())
 	pkgw.logger.Info("buildermgr.pkgWatcher.AddNamespace: done", zap.String("namespace", ns))
 }
+
+// RemoveNamespace deregisters a namespace from the package watcher.
+func (pkgw *packageWatcher) RemoveNamespace(ns string) {
+	if cancel, ok := pkgw.nsCancels[ns]; ok {
+		cancel()
+		delete(pkgw.nsCancels, ns)
+	}
+	delete(pkgw.pkgInformer, ns)
+	delete(pkgw.podInformer, ns)
+	pkgw.logger.Info("buildermgr.pkgWatcher.RemoveNamespace: cleaned up", zap.String("namespace", ns))
+}

pkg/executor/executortype/container/containermgr.go

@@ -90,6 +90,10 @@ type (
 		objectReaperIntervalSecond time.Duration
 
 		enableOwnerReferences bool
+
+		// nsCancels holds per-namespace context cancel functions so informer
+		// factories started in AddNamespace can be stopped on RemoveNamespace.
+		nsCancels map[string]context.CancelFunc
 	}
 )
 
@@ -132,8 +136,7 @@ func MakeContainer(
 		deplLister:                 make(map[string]appslisters.DeploymentLister),
 		deplListerSynced:           make(map[string]k8sCache.InformerSynced),
 		svcLister:                  make(map[string]corelisters.ServiceLister),
-		svcListerSynced:            make(map[string]k8sCache.InformerSynced),
+		svcListerSynced:            make(map[string]k8sCache.InformerSynced), nsCancels: make(map[string]context.CancelFunc),
-
 		enableOwnerReferences: utils.IsOwnerReferencesEnabled(),
 	}
 
@@ -833,9 +836,36 @@ func (caaf *Container) AddNamespace(ctx context.Context, ns string, mgr manager.
 		return fmt.Errorf("AddNamespace %s (container): add function handler: %w", ns, err)
 	}
 
-	finformer.Start(ctx.Done())
+	// Create a per-namespace cancellable context so RemoveNamespace can stop
-	cnmInformer.Start(ctx.Done())
+	// these specific informer factories without affecting the whole process.
+	nsCtx, nsCancel := context.WithCancel(ctx)
+	caaf.nsCancels[ns] = nsCancel
+
+	finformer.Start(nsCtx.Done())
+	cnmInformer.Start(nsCtx.Done())
 
 	caaf.logger.Info("AddNamespace: done (container)", zap.String("namespace", ns))
 	return nil
 }
+
+// RemoveNamespace deregisters a namespace from the container executor.
+// Cancels the per-namespace informer context and clears all lister maps so that
+// a subsequent AddNamespace call will re-register the namespace correctly.
+func (caaf *Container) RemoveNamespace(ctx context.Context, ns string) error {
+	if ns == "" {
+		return nil
+	}
+	caaf.logger.Info("RemoveNamespace: cleaning up namespace (container)", zap.String("namespace", ns))
+
+	if cancel, ok := caaf.nsCancels[ns]; ok {
+		cancel()
+		delete(caaf.nsCancels, ns)
+	}
+
+	delete(caaf.deplLister, ns)
+	delete(caaf.deplListerSynced, ns)
+	delete(caaf.svcLister, ns)
+	delete(caaf.svcListerSynced, ns)
+
+	return nil
+}

pkg/executor/executortype/executortype.go

@@ -74,4 +74,9 @@ type ExecutorType interface {
 	// starts watching Fission CRDs and K8s resources in it without a pod restart.
 	// Called when a Namespace with label fission.io/managed=true appears.
 	AddNamespace(ctx context.Context, ns string, mgr manager.Interface) error
+
+	// RemoveNamespace deregisters a namespace from the executor, cancelling its
+	// informer goroutines and clearing dedup state so that a re-add works correctly.
+	// Called when a Namespace with label fission.io/managed=true is removed.
+	RemoveNamespace(ctx context.Context, ns string) error
 }

pkg/executor/executortype/newdeploy/newdeploymgr.go

@@ -94,6 +94,10 @@ type (
 		objectReaperIntervalSecond time.Duration
 
 		enableOwnerReferences bool
+
+		// nsCancels holds per-namespace context cancel functions so informer
+		// factories started in AddNamespace can be stopped on RemoveNamespace.
+		nsCancels map[string]context.CancelFunc
 	}
 )
 
@@ -140,8 +144,7 @@ func MakeNewDeploy(
 		deplLister:       make(map[string]appslisters.DeploymentLister),
 		deplListerSynced: make(map[string]k8sCache.InformerSynced),
 		svcLister:        make(map[string]corelisters.ServiceLister),
-		svcListerSynced:  make(map[string]k8sCache.InformerSynced),
+		svcListerSynced:  make(map[string]k8sCache.InformerSynced), nsCancels: make(map[string]context.CancelFunc),
-
 		enableOwnerReferences: utils.IsOwnerReferencesEnabled(),
 	}
 
@@ -949,9 +952,36 @@ func (deploy *NewDeploy) AddNamespace(ctx context.Context, ns string, mgr manage
 		return fmt.Errorf("AddNamespace %s (newdeploy): add environment handler: %w", ns, err)
 	}
 
-	finformer.Start(ctx.Done())
+	// Create a per-namespace cancellable context so RemoveNamespace can stop
-	ndmInformer.Start(ctx.Done())
+	// these specific informer factories without affecting the whole process.
+	nsCtx, nsCancel := context.WithCancel(ctx)
+	deploy.nsCancels[ns] = nsCancel
+
+	finformer.Start(nsCtx.Done())
+	ndmInformer.Start(nsCtx.Done())
 
 	deploy.logger.Info("AddNamespace: done (newdeploy)", zap.String("namespace", ns))
 	return nil
 }
+
+// RemoveNamespace deregisters a namespace from the newdeploy executor.
+// Cancels the per-namespace informer context and clears all lister maps so that
+// a subsequent AddNamespace call will re-register the namespace correctly.
+func (deploy *NewDeploy) RemoveNamespace(ctx context.Context, ns string) error {
+	if ns == "" {
+		return nil
+	}
+	deploy.logger.Info("RemoveNamespace: cleaning up namespace (newdeploy)", zap.String("namespace", ns))
+
+	if cancel, ok := deploy.nsCancels[ns]; ok {
+		cancel()
+		delete(deploy.nsCancels, ns)
+	}
+
+	delete(deploy.deplLister, ns)
+	delete(deploy.deplListerSynced, ns)
+	delete(deploy.svcLister, ns)
+	delete(deploy.svcListerSynced, ns)
+
+	return nil
+}

pkg/executor/executortype/poolmgr/gpm.go

@@ -98,6 +98,10 @@ type (
 
 		podSpecPatch               *apiv1.PodSpec
 		objectReaperIntervalSecond time.Duration
+
+		// nsCancels holds per-namespace context cancel functions so informer
+		// factories started in AddNamespace can be stopped on RemoveNamespace.
+		nsCancels map[string]context.CancelFunc
 	}
 	request struct {
 		requestType
@@ -159,6 +163,7 @@ func MakeGenericPoolManager(ctx context.Context,
 		objectReaperIntervalSecond: time.Duration(executorUtils.GetObjectReaperInterval(logger, fv1.ExecutorTypePoolmgr, 5)) * time.Second,
 		podLister:                  make(map[string]corelisters.PodLister),
 		podListerSynced:            make(map[string]k8sCache.InformerSynced),
+		nsCancels:                  make(map[string]context.CancelFunc),
 	}
 	for ns, informerFactory := range gpmInformerFactory {
 		gpm.podLister[ns] = informerFactory.Core().V1().Pods().Lister()
@@ -833,10 +838,40 @@ func (gpm *GenericPoolManager) AddNamespace(ctx context.Context, ns string, mgr
 		return fmt.Errorf("AddNamespace %s: register informers: %w", ns, err)
 	}
 
+	// Create a per-namespace cancellable context so RemoveNamespace can stop
+	// these specific informer factories without affecting the whole process.
+	nsCtx, nsCancel := context.WithCancel(ctx)
+	gpm.nsCancels[ns] = nsCancel
+
 	// Start the factories — they will begin syncing immediately.
-	finformer.Start(ctx.Done())
+	finformer.Start(nsCtx.Done())
-	gpmInformer.Start(ctx.Done())
+	gpmInformer.Start(nsCtx.Done())
 
 	gpm.logger.Info("AddNamespace: informers started for namespace", zap.String("namespace", ns))
 	return nil
 }
+
+// RemoveNamespace deregisters a namespace from the poolmgr executor.
+// Cancels the per-namespace informer context and clears all lister maps so that
+// a subsequent AddNamespace call will re-register the namespace correctly.
+func (gpm *GenericPoolManager) RemoveNamespace(ctx context.Context, ns string) error {
+	if ns == "" {
+		return nil
+	}
+	gpm.logger.Info("RemoveNamespace: cleaning up namespace (poolmgr)", zap.String("namespace", ns))
+
+	// Stop informer factories for this namespace.
+	if cancel, ok := gpm.nsCancels[ns]; ok {
+		cancel()
+		delete(gpm.nsCancels, ns)
+	}
+
+	// Clear gpm-level lister maps so dedup passes on next AddNamespace.
+	delete(gpm.podLister, ns)
+	delete(gpm.podListerSynced, ns)
+
+	// Clear PoolPodController lister maps.
+	gpm.poolPodC.RemoveNamespace(ns)
+
+	return nil
+}

pkg/executor/executortype/poolmgr/poolpodcontroller.go

@@ -528,3 +528,14 @@ func (p *PoolPodController) AddNamespaceInformers(
 	p.logger.Info("AddNamespaceInformers: registered informers for namespace", zap.String("namespace", ns))
 	return nil
 }
+
+// RemoveNamespace clears all per-namespace lister state in the PoolPodController.
+// Called from GenericPoolManager.RemoveNamespace so the dedup check in AddNamespace
+// will pass if the namespace is re-added later.
+func (p *PoolPodController) RemoveNamespace(ns string) {
+	delete(p.envLister, ns)
+	delete(p.envListerSynced, ns)
+	delete(p.podLister, ns)
+	delete(p.podListerSynced, ns)
+	p.logger.Info("PoolPodController.RemoveNamespace: cleared lister state", zap.String("namespace", ns))
+}

pkg/executor/multitenant/namespace_subscriber.go

@@ -24,6 +24,9 @@ func NewNamespaceSubscriber(
 			registerNamespace(ctx, logger, kubernetesClient, record.Name, executorTypes, mgr)
 			return nil
 		},
+		RemoveFunc: func(ctx context.Context, record utils.NamespaceRecord) error {
+			return deregisterNamespace(ctx, logger, record.Name, executorTypes)
+		},
 		ResyncFunc: func(ctx context.Context, record utils.NamespaceRecord) error {
 			registerNamespace(ctx, logger, kubernetesClient, record.Name, executorTypes, mgr)
 			return nil

pkg/executor/multitenant/ns_watcher.go

@@ -87,7 +87,9 @@ func StartNSWatcher(
 	executorTypes map[fv1.ExecutorType]executortype.ExecutorType,
 	mgr manager.Interface,
 ) {
-	_, err := utils.RunManagedNamespaceWatcher(ctx, logger, kubernetesClient, mgr, utils.NewDefaultManagedNamespaceWatcherConfig("multitenant.NSWatcher", NewNamespaceSubscriber(logger, kubernetesClient, executorTypes, mgr)))
+	config := utils.NewDefaultManagedNamespaceWatcherConfig("multitenant.NSWatcher", NewNamespaceSubscriber(logger, kubernetesClient, executorTypes, mgr))
+	config.RemovalStrategy = utils.NamespaceRemovalStrategyDispatchRemove
+	_, err := utils.RunManagedNamespaceWatcher(ctx, logger, kubernetesClient, mgr, config)
 	if err != nil {
 		logger.Error("multitenant.NSWatcher: BootstrapAndDispatch failed", zap.Error(err))
 	}
@@ -135,3 +137,26 @@ func registerExecutorTypes(
 	}
 	return joinErr
 }
+
+// deregisterNamespace calls RemoveNamespace on every executor type for the given namespace.
+// Called when a Namespace with label fission.io/managed=true is removed.
+func deregisterNamespace(
+	ctx context.Context,
+	logger *zap.Logger,
+	ns string,
+	executorTypes map[fv1.ExecutorType]executortype.ExecutorType,
+) error {
+	var joinErr error
+
+	for _, et := range executorTypes {
+		if err := et.RemoveNamespace(ctx, ns); err != nil {
+			logger.Error("multitenant.NSWatcher: RemoveNamespace failed",
+				zap.String("namespace", ns),
+				zap.Error(err),
+			)
+			joinErr = errors.Join(joinErr, err)
+		}
+	}
+	logger.Info("multitenant.NSWatcher: deregistered namespace", zap.String("namespace", ns))
+	return joinErr
+}

pkg/executor/multitenant/ns_watcher_test.go

@@ -46,6 +46,7 @@ func (f *fakeExecutorType) AddNamespace(ctx context.Context, ns string, mgr mana
 	f.lastNamespace = ns
 	return f.addErr
 }
+func (f *fakeExecutorType) RemoveNamespace(ctx context.Context, ns string) error { return nil }
 
 var _ executortype.ExecutorType = (*fakeExecutorType)(nil)
 

pkg/router/httpTriggers.go

@@ -50,16 +50,18 @@ type HTTPTriggerSet struct {
 	*functionServiceMap
 	*mutableRouter
 
-	logger                     *zap.Logger
+	logger          *zap.Logger
-	fissionClient              versioned.Interface
+	fissionClient   versioned.Interface
-	kubeClient                 kubernetes.Interface
+	kubeClient      kubernetes.Interface
-	executor                   eclient.ClientInterface
+	executor        eclient.ClientInterface
-	resolver                   *functionReferenceResolver
+	resolver        *functionReferenceResolver
-	triggers                   []fv1.HTTPTrigger
+	triggers        []fv1.HTTPTrigger
-	triggerInformer            map[string]k8sCache.SharedIndexInformer
+	triggerInformer map[string]k8sCache.SharedIndexInformer
-	functions                  []fv1.Function
+	functions       []fv1.Function
-	funcInformer               map[string]k8sCache.SharedIndexInformer
+	funcInformer    map[string]k8sCache.SharedIndexInformer
-	informerMu                 sync.RWMutex
+	informerMu      sync.RWMutex
+	// nsCancels holds per-namespace context cancel functions for informer lifecycle.
+	nsCancels                  map[string]context.CancelFunc
 	updateRouterRequestChannel chan struct{}
 	tsRoundTripperParams       *tsRoundTripperParams
 	isDebugEnv                 bool
@@ -84,6 +86,7 @@ func makeHTTPTriggerSet(logger *zap.Logger, fmap *functionServiceMap, fissionCli
 		svcAddrUpdateThrottler:     actionThrottler,
 		unTapServiceTimeout:        unTapServiceTimeout,
 		syncDebouncer:              debounce.New(time.Millisecond * 20),
+		nsCancels:                  make(map[string]context.CancelFunc),
 	}
 	httpTriggerSet.triggerInformer = utils.GetInformersForNamespaces(fissionClient, time.Minute*30, fv1.HttpTriggerResource)
 	httpTriggerSet.funcInformer = utils.GetInformersForNamespaces(fissionClient, time.Minute*30, fv1.FunctionResource)
@@ -526,11 +529,39 @@ func (ts *HTTPTriggerSet) AddNamespace(ctx context.Context, ns string, mgr manag
 		ns + "/trigger": triggerInf,
 		ns + "/func":    funcInf,
 	})
-	factory.Start(ctx.Done())
+
+	// Create a per-namespace cancellable context for informer lifecycle.
+	nsCtx, nsCancel := context.WithCancel(ctx)
+	ts.nsCancels[ns] = nsCancel
+
+	factory.Start(nsCtx.Done())
 	// Wait for cache to sync before rebuilding the router, so triggers are visible.
-	k8sCache.WaitForCacheSync(ctx.Done(), triggerInf.HasSynced, funcInf.HasSynced)
+	k8sCache.WaitForCacheSync(nsCtx.Done(), triggerInf.HasSynced, funcInf.HasSynced)
 
 	ts.logger.Info("router.AddNamespace: done", zap.String("namespace", ns))
 	ts.syncTriggers()
 	return nil
 }
+
+// RemoveNamespace deregisters a namespace from the router.
+// Cancels the per-namespace informer context, removes informers from internal maps,
+// and triggers a syncTriggers so stale routes are removed immediately.
+func (ts *HTTPTriggerSet) RemoveNamespace(ns string) {
+	if ns == "" {
+		return
+	}
+	ts.logger.Info("router.RemoveNamespace: cleaning up namespace", zap.String("namespace", ns))
+
+	if cancel, ok := ts.nsCancels[ns]; ok {
+		cancel()
+		delete(ts.nsCancels, ns)
+	}
+
+	ts.informerMu.Lock()
+	delete(ts.triggerInformer, ns)
+	delete(ts.funcInformer, ns)
+	ts.informerMu.Unlock()
+
+	ts.syncTriggers()
+	ts.logger.Info("router.RemoveNamespace: done", zap.String("namespace", ns))
+}

pkg/router/namespace_subscriber.go

@@ -11,12 +11,22 @@ type routerNamespaceAdder interface {
 	AddNamespace(ctx context.Context, ns string, mgr manager.Interface) error
 }
 
+type routerNamespaceRemover interface {
+	RemoveNamespace(ns string)
+}
+
 func NewNamespaceSubscriber(ts routerNamespaceAdder, mgr manager.Interface) utils.NamespaceSubscriber {
 	return utils.NamespaceSubscriberFuncs{
 		SubscriberName: "router",
 		AddFunc: func(ctx context.Context, record utils.NamespaceRecord) error {
 			return registerRouterNamespace(ctx, record.Name, ts, mgr)
 		},
+		RemoveFunc: func(ctx context.Context, record utils.NamespaceRecord) error {
+			if r, ok := ts.(routerNamespaceRemover); ok {
+				r.RemoveNamespace(record.Name)
+			}
+			return nil
+		},
 		ResyncFunc: func(ctx context.Context, record utils.NamespaceRecord) error {
 			return registerRouterNamespace(ctx, record.Name, ts, mgr)
 		},

pkg/router/ns_watcher.go

@@ -25,7 +25,9 @@ func StartNSWatcher(
 	ts *HTTPTriggerSet,
 	mgr manager.Interface,
 ) {
-	_, err := utils.RunManagedNamespaceWatcher(ctx, logger, kubeClient, mgr, utils.NewDefaultManagedNamespaceWatcherConfig("router.NSWatcher", NewNamespaceSubscriber(ts, mgr)))
+	config := utils.NewDefaultManagedNamespaceWatcherConfig("router.NSWatcher", NewNamespaceSubscriber(ts, mgr))
+	config.RemovalStrategy = utils.NamespaceRemovalStrategyDispatchRemove
+	_, err := utils.RunManagedNamespaceWatcher(ctx, logger, kubeClient, mgr, config)
 	if err != nil {
 		logger.Error("router.NSWatcher: BootstrapAndDispatch failed", zap.Error(err))
 	}