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

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))
+}