Use Clientset interface instead of type for Fission/kubernetes clients (#2416)

Using interface makes it easy to create a fake client and unit test
a specific portion of the code. We should be able to more write unit
test and increase coverage of code with this change.

Signed-off-by: Sanket Sudake <sanketsudake@gmail.com>

pkg/kubewatcher/kubewatcher.go

@@ -52,7 +52,7 @@ type (
 	KubeWatcher struct {
 		logger           *zap.Logger
 		watches          map[types.UID]watchSubscription
-		kubernetesClient *kubernetes.Clientset
+		kubernetesClient kubernetes.Interface
 		requestChannel   chan *kubeWatcherRequest
 		publisher        publisher.Publisher
 	}
@@ -63,7 +63,7 @@ type (
 		kubeWatch           watch.Interface
 		lastResourceVersion string
 		stopped             *int32
-		kubernetesClient    *kubernetes.Clientset
+		kubernetesClient    kubernetes.Interface
 		publisher           publisher.Publisher
 	}
 
@@ -77,7 +77,7 @@ type (
 	}
 )
 
-func MakeKubeWatcher(ctx context.Context, logger *zap.Logger, kubernetesClient *kubernetes.Clientset, publisher publisher.Publisher) *KubeWatcher {
+func MakeKubeWatcher(ctx context.Context, logger *zap.Logger, kubernetesClient kubernetes.Interface, publisher publisher.Publisher) *KubeWatcher {
 	kw := &KubeWatcher{
 		logger:           logger.Named("kube_watcher"),
 		watches:          make(map[types.UID]watchSubscription),
@@ -149,7 +149,7 @@ func printKubernetesObject(obj runtime.Object, w io.Writer) error {
 	return err
 }
 
-func createKubernetesWatch(ctx context.Context, kubeClient *kubernetes.Clientset, w *fv1.KubernetesWatchTrigger, resourceVersion string) (watch.Interface, error) {
+func createKubernetesWatch(ctx context.Context, kubeClient kubernetes.Interface, w *fv1.KubernetesWatchTrigger, resourceVersion string) (watch.Interface, error) {
 	var wi watch.Interface
 	var err error
 	var watchTimeoutSec int64 = 120
@@ -198,7 +198,7 @@ func (kw *KubeWatcher) removeWatch(w *fv1.KubernetesWatchTrigger) error {
 	return nil
 }
 
-func MakeWatchSubscription(ctx context.Context, logger *zap.Logger, w *fv1.KubernetesWatchTrigger, kubeClient *kubernetes.Clientset, publisher publisher.Publisher) (*watchSubscription, error) {
+func MakeWatchSubscription(ctx context.Context, logger *zap.Logger, w *fv1.KubernetesWatchTrigger, kubeClient kubernetes.Interface, publisher publisher.Publisher) (*watchSubscription, error) {
 	var stopped int32 = 0
 	ws := &watchSubscription{
 		logger:              logger.Named("watch_subscription"),

pkg/kubewatcher/main.go

@@ -32,7 +32,7 @@ func Start(ctx context.Context, logger *zap.Logger, routerUrl string) error {
 		return errors.Wrap(err, "failed to get fission or kubernetes client")
 	}
 
-	err = fissionClient.WaitForCRDs()
+	err = crd.WaitForCRDs(fissionClient)
 	if err != nil {
 		return errors.Wrap(err, "error waiting for CRDs")
 	}

pkg/kubewatcher/watchSync.go

@@ -23,18 +23,18 @@ import (
 	"go.uber.org/zap"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 
-	"github.com/fission/fission/pkg/crd"
+	"github.com/fission/fission/pkg/generated/clientset/versioned"
 )
 
 type (
 	WatchSync struct {
 		logger      *zap.Logger
-		client      *crd.FissionClient
+		client      versioned.Interface
 		kubeWatcher *KubeWatcher
 	}
 )
 
-func MakeWatchSync(logger *zap.Logger, client *crd.FissionClient, kubeWatcher *KubeWatcher) *WatchSync {
+func MakeWatchSync(logger *zap.Logger, client versioned.Interface, kubeWatcher *KubeWatcher) *WatchSync {
 	ws := &WatchSync{
 		logger:      logger.Named("watch_sync"),
 		client:      client,