Allow users to specify namespace for Kubernetes informers (kubeflow#851)

* Allow users to specify namespace for Kubernetes informers

* Change variable informerNamespace to namespace

backend/src/crd/controller/scheduledworkflow/main.go

@@ -33,6 +33,7 @@ import (
 var (
 	masterURL  string
 	kubeconfig string
+	namespace  string
 )
 
 func main() {
@@ -61,8 +62,15 @@ func main() {
 		log.Fatalf("Error building workflow clientset: %s", err.Error())
 	}
 
-	scheduleInformerFactory := swfinformers.NewSharedInformerFactory(scheduleClient, time.Second*30)
-	workflowInformerFactory := workflowinformers.NewSharedInformerFactory(workflowClient, time.Second*30)
+	var scheduleInformerFactory swfinformers.SharedInformerFactory
+	var workflowInformerFactory workflowinformers.SharedInformerFactory
+	if namespace == "" {
+		scheduleInformerFactory = swfinformers.NewSharedInformerFactory(scheduleClient, time.Second*30)
+		workflowInformerFactory = workflowinformers.NewSharedInformerFactory(workflowClient, time.Second*30)
+	} else {
+		scheduleInformerFactory = swfinformers.NewFilteredSharedInformerFactory(scheduleClient, time.Second*30, namespace, nil)
+		workflowInformerFactory = workflowinformers.NewFilteredSharedInformerFactory(workflowClient, time.Second*30, namespace, nil)
+	}
 
 	controller := NewController(
 		kubeClient,
@@ -83,4 +91,5 @@ func main() {
 func init() {
 	flag.StringVar(&kubeconfig, "kubeconfig", "", "Path to a kubeconfig. Only required if out-of-cluster.")
 	flag.StringVar(&masterURL, "master", "", "The address of the Kubernetes API server. Overrides any value in kubeconfig. Only required if out-of-cluster.")
+	flag.StringVar(&namespace, "namespace", "", "The namespace name used for Kubernetes informers to obtain the listers.")
 }