rest client: use interface instead of structure pointer

pkg/cluster/cluster.go

@@ -37,7 +37,7 @@ var (
 // Config contains operator-wide clients and configuration used from a cluster. TODO: remove struct duplication.
 type Config struct {
 	KubeClient          *kubernetes.Clientset //TODO: move clients to the better place?
-	RestClient          *rest.RESTClient
+	RestClient          rest.Interface
 	RestConfig          *rest.Config
 	TeamsAPIClient      *teams.API
 	OpConfig            config.Config

pkg/controller/controller.go

@@ -20,7 +20,7 @@ import (
 type Config struct {
 	RestConfig          *rest.Config
 	KubeClient          *kubernetes.Clientset
-	RestClient          *rest.RESTClient
+	RestClient          rest.Interface
 	TeamsAPIClient      *teams.API
 	InfrastructureRoles map[string]spec.PgUser
 }

pkg/util/k8sutil/k8sutil.go

@@ -38,7 +38,7 @@ func ResourceNotFound(err error) bool {
 	return apierrors.IsNotFound(err)
 }
 
-func KubernetesRestClient(c *rest.Config) (*rest.RESTClient, error) {
+func KubernetesRestClient(c *rest.Config) (rest.Interface, error) {
 	c.GroupVersion = &schema.GroupVersion{Version: constants.K8sVersion}
 	c.APIPath = constants.K8sAPIPath
 	c.NegotiatedSerializer = serializer.DirectCodecFactory{CodecFactory: api.Codecs}