Hold startup until etcd has stabilized cluster version

Uncomment gate for version detection.

Author: smarterclayton

pkg/cmd/server/etcd/etcdserver/run.go

@@ -70,6 +70,7 @@ func RunEtcd(etcdServerConfig *configapi.EtcdConfig) {
 		glog.Fatalf("Unable to start etcd: %v", err)
 	}
 
+	ready := make(chan struct{})
 	go func() {
 		defer e.Close()
 
@@ -80,13 +81,15 @@ func RunEtcd(etcdServerConfig *configapi.EtcdConfig) {
 			for min := semver.Must(semver.NewVersion("3.0.0")); e.Server.ClusterVersion() == nil || e.Server.ClusterVersion().LessThan(*min); {
 				time.Sleep(25 * time.Millisecond)
 			}
+			close(ready)
 			glog.Infof("Started etcd at %s", etcdServerConfig.Address)
 		case <-time.After(60 * time.Second):
 			glog.Warning("etcd took too long to start, stopped")
 			e.Server.Stop() // trigger a shutdown
 		}
 		glog.Fatalf("etcd has returned an error: %v", <-e.Err())
 	}()
+	<-ready
 }
 
 // addressToURLs turns a host:port comma delimited list into an array valid

pkg/cmd/server/start/start_master.go

@@ -474,16 +474,15 @@ func StartAPI(oc *origin.MasterConfig, kc *kubernetes.MasterConfig) error {
 	}
 
 	// verify we can connect to etcd with the provided config
-	// TODO(post-1.6.1-rebase): uncomment etcd3 support
-	//if len(kc.Options.APIServerArguments) > 0 && len(kc.Options.APIServerArguments["storage-backend"]) > 0 && kc.Options.APIServerArguments["storage-backend"][0] == "etcd2" {
-	if _, err := etcd.GetAndTestEtcdClient(oc.Options.EtcdClientInfo); err != nil {
-		return err
+	if len(kc.Options.APIServerArguments) > 0 && len(kc.Options.APIServerArguments["storage-backend"]) > 0 && kc.Options.APIServerArguments["storage-backend"][0] == "etcd3" {
+		if _, err := etcd.GetAndTestEtcdClientV3(oc.Options.EtcdClientInfo); err != nil {
+			return err
+		}
+	} else {
+		if _, err := etcd.GetAndTestEtcdClient(oc.Options.EtcdClientInfo); err != nil {
+			return err
+		}
 	}
-	//} else {
-	//if _, err := etcd.GetAndTestEtcdClientV3(oc.Options.EtcdClientInfo); err != nil {
-	//return err
-	//}
-	//}
 
 	// Must start policy caching immediately
 	oc.Informers.StartCore(utilwait.NeverStop)