Address comments from out-of-band review

pkg/config/config.go

@@ -32,22 +32,20 @@ var (
 )
 
 func init() {
-	// Check if flag is already set so that the library may be double vendored without crashing the program
-	if f := flag.Lookup("kubeconfig"); f == nil {
-		flag.StringVar(&kubeconfig, "kubeconfig", "",
-			"Path to a kubeconfig. Only required if out-of-cluster.")
-	}
+	// TODO: Fix this to allow double vendoring this library but still register flags on behalf of users
+	flag.StringVar(&kubeconfig, "kubeconfig", "",
+		"Path to a kubeconfig. Only required if out-of-cluster.")
 
-	// Check if flag is already set so that the library may be double vendored without crashing the program
-	if f := flag.Lookup("master"); f == nil {
-		flag.StringVar(&masterURL, "master", "",
-			"The address of the Kubernetes API server. Overrides any value in 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.")
 }
 
-// GetConfig uses the kubeconfig file at kubeconfig to create a rest.Config for talking to a Kubernetes
-// apiserver.  If kubeconfig is empty it will look for kubeconfig in the default locations.
+// GetConfig creates a *rest.Config for talking to a Kubernetes apiserver.
+// If --kubeconfig is set, will use the kubeconfig file at that location.  Otherwise will assume running
+// in cluster and use the cluster provided kubeconfig.
+//
+// Will log.Fatal if KubernetesInformers cannot be created
 func GetConfig() (*rest.Config, error) {
 	if len(kubeconfig) > 0 {
 		return clientcmd.BuildConfigFromFlags(masterURL, kubeconfig)
@@ -56,8 +54,9 @@ func GetConfig() (*rest.Config, error) {
 	}
 }
 
-// GetConfigOrDie uses the kubeconfig file at kubeconfig to create a rest.Config for talking to a Kubernetes
-// apiserver.  If kubeconfig is empty it will look for kubeconfig in the default locations.
+// GetConfig creates a *rest.Config for talking to a Kubernetes apiserver.
+// If --kubeconfig is set, will use the kubeconfig file at that location.  Otherwise will assume running
+// in cluster and use the cluster provided kubeconfig.
 func GetConfigOrDie() *rest.Config {
 	config, err := GetConfig()
 	if err != nil {
@@ -66,9 +65,54 @@ func GetConfigOrDie() *rest.Config {
 	return config
 }
 
-// GetKubernetesInformersOrDie uses the kubeconfig file at kubeconfig to create a informers.SharedInformerFactory
-// for talking to a Kubernetes apiserver.  If kubeconfig is empty it will look for kubeconfig in the
-// default locations.
+// GetKubernetesClientSet creates a *kubernetes.ClientSet for talking to a Kubernetes apiserver.
+// If --kubeconfig is set, will use the kubeconfig file at that location.  Otherwise will assume running
+// in cluster and use the cluster provided kubeconfig.
+func GetKubernetesClientSet() (*kubernetes.Clientset, error) {
+	config, err := GetConfig()
+	if err != nil {
+		return nil, err
+	}
+	return kubernetes.NewForConfig(config)
+}
+
+// GetKubernetesClientSetOrDie creates a *kubernetes.ClientSet for talking to a Kubernetes apiserver.
+// If --kubeconfig is set, will use the kubeconfig file at that location.  Otherwise will assume running
+// in cluster and use the cluster provided kubeconfig.
+//
+// Will log.Fatal if KubernetesInformers cannot be created
+func GetKubernetesClientSetOrDie() (*kubernetes.Clientset, error) {
+	cs, err := GetKubernetesClientSet()
+	if err != nil {
+		log.Fatalf("%v", err)
+	}
+	return cs, nil
+}
+
+// GetKubernetesInformers creates a informers.SharedInformerFactory for talking to a Kubernetes apiserver.
+// If --kubeconfig is set, will use the kubeconfig file at that location.  Otherwise will assume running
+// in cluster and use the cluster provided kubeconfig.
+func GetKubernetesInformers() (informers.SharedInformerFactory, error) {
+	config, err := GetConfig()
+	if err != nil {
+		return nil, err
+	}
+	i, err := kubernetes.NewForConfig(config)
+	if err != nil {
+		return nil, err
+	}
+	return informers.NewSharedInformerFactory(i, time.Minute*5), nil
+}
+
+// GetKubernetesInformers creates a informers.SharedInformerFactory for talking to a Kubernetes apiserver.
+// If --kubeconfig is set, will use the kubeconfig file at that location.  Otherwise will assume running
+// in cluster and use the cluster provided kubeconfig.
+//
+// Will log.Fatal if KubernetesInformers cannot be created
 func GetKubernetesInformersOrDie() informers.SharedInformerFactory {
-	return informers.NewSharedInformerFactory(kubernetes.NewForConfigOrDie(GetConfigOrDie()), time.Minute*5)
+	i, err := GetKubernetesInformers()
+	if err != nil {
+		log.Fatalf("%v", err)
+	}
+	return i
 }

pkg/controller/example_controller_test.go

@@ -41,7 +41,7 @@ func ExampleGenericController() {
 		log.Fatalf("Could not set informer %v", err)
 	}
 
-	// Step 3.1: Create a new Pod controller to reconcile Pods changes
+	// Step 2.1: Create a new Pod controller to reconcile Pods changes
 	podController := &controller.GenericController{
 		Reconcile: func(key types.ReconcileKey) error {
 			fmt.Printf("Reconciling Pod %v\n", key)
@@ -53,7 +53,7 @@ func ExampleGenericController() {
 	}
 	controller.AddController(podController)
 
-	// Step 3.2: Create a new ReplicaSet controller to reconcile ReplicaSet changes
+	// Step 2.2: Create a new ReplicaSet controller to reconcile ReplicaSet changes
 	rsController := &controller.GenericController{
 		Reconcile: func(key types.ReconcileKey) error {
 			fmt.Printf("Reconciling ReplicaSet %v\n", key)
@@ -72,6 +72,6 @@ func ExampleGenericController() {
 	}
 	controller.AddController(rsController)
 
-	// Step 4: RunInformersAndControllers all informers and controllers
+	// Step 3: RunInformersAndControllers all informers and controllers
 	controller.RunInformersAndControllers(run.CreateRunArguments())
 }