Avoid exposing sensitive data to client (#1543)

This PR changes the behavior of controller API which
wrongly exposes sensitive data to the client. Now, the
API only returns success if secret/configmap exists;
otherwise, an error will be returned.

pkg/fission-cli/cmd/function/update.go

@@ -87,7 +87,7 @@ func (opts *UpdateSubCommand) complete(input cli.Input) error {
 
 		// check that the referenced secret is in the same ns as the function, if not give a warning.
 		for _, secretName := range secretNames {
-			_, err := opts.Client().V1().Misc().SecretGet(&metav1.ObjectMeta{
+			err := opts.Client().V1().Misc().SecretExists(&metav1.ObjectMeta{
 				Namespace: fnNamespace,
 				Name:      secretName,
 			})
@@ -111,7 +111,7 @@ func (opts *UpdateSubCommand) complete(input cli.Input) error {
 
 		// check that the referenced cfgmap is in the same ns as the function, if not give a warning.
 		for _, cfgMapName := range cfgMapNames {
-			_, err := opts.Client().V1().Misc().ConfigMapGet(&metav1.ObjectMeta{
+			err := opts.Client().V1().Misc().ConfigMapExists(&metav1.ObjectMeta{
 				Namespace: fnNamespace,
 				Name:      cfgMapName,
 			})