Made NamespaceManager.Run indempotent and added graceful shutdown

pkg/namespace/namespace_controller.go

@@ -62,14 +62,24 @@ func NewNamespaceManager(kubeClient client.Interface, resyncPeriod time.Duration
 	)
 
 	return &NamespaceManager{
-		controller:     controller,
-		StopEverything: make(chan struct{}),
+		controller: controller,
 	}
 }
 
 // Run begins observing the system.  It starts a goroutine and returns immediately.
 func (nm *NamespaceManager) Run() {
-	go nm.controller.Run(nm.StopEverything)
+	if nm.StopEverything == nil {
+		nm.StopEverything = make(chan struct{})
+		go nm.controller.Run(nm.StopEverything)
+	}
+}
+
+// Stop gracefully shutsdown this controller
+func (nm *NamespaceManager) Stop() {
+	if nm.StopEverything != nil {
+		close(nm.StopEverything)
+		nm.StopEverything = nil
+	}
 }
 
 // finalized returns true if the spec.finalizers is empty list