skipper: use kubernetes cluster client to discover redis shards

Fixes #2476

Signed-off-by: Alexander Yastrebov <alexander.yastrebov@zalando.de>

skipper.go

@@ -1684,24 +1684,33 @@ func run(o Options, sig chan os.Signal, idleConnsCH chan struct{}) error {
 			kdc := findKubernetesDataclient(dataClients)
 			if kdc != nil {
 				redisOptions.AddrUpdater = getRedisUpdaterFunc(o.KubernetesRedisServiceNamespace, o.KubernetesRedisServiceName, kdc)
-				_, err = redisOptions.AddrUpdater()
+			} else {
+				clusterClient, err := kubernetes.NewClusterClient(o.KubernetesDataClientOptions())
 				if err != nil {
-					log.Errorf("Failed to update redis address %v", err)
+					log.Errorf("Failed to create kubernetes cluster client: %v", err)
 					return err
 				}
-			} else {
-				log.Errorf("Failed to find kubernetes dataclient, but redis shards should be get by kubernetes svc %s/%s", o.KubernetesRedisServiceNamespace, o.KubernetesRedisServiceName)
+				redisOptions.AddrUpdater = func() ([]string, error) {
+					a, err := clusterClient.LoadEndpointAddresses(o.KubernetesRedisServiceNamespace, o.KubernetesRedisServiceName)
+					log.Debugf("LoadEndpointAddresses found %d redis endpoints, err: %v", len(a), err)
+					return a, err
+				}
+			}
+
+			_, err = redisOptions.AddrUpdater()
+			if err != nil {
+				log.Errorf("Failed to update redis addresses: %v", err)
+				return err
 			}
 		} else if redisOptions != nil && o.SwarmRedisEndpointsRemoteURL != "" {
 			log.Infof("Use remote address %s to fetch updates redis shards", o.SwarmRedisEndpointsRemoteURL)
 			redisOptions.AddrUpdater = updateEndpointsFromURL(o.SwarmRedisEndpointsRemoteURL)
 			_, err = redisOptions.AddrUpdater()
 			if err != nil {
-				log.Errorf("Failed to update redis endpoints from URL %v", err)
+				log.Errorf("Failed to update redis endpoints from URL: %v", err)
 				return err
 			}
 		}
-
 	}
 
 	var ratelimitRegistry *ratelimit.Registry