kube-apiserver: make apiserver chain testable

cmd/kube-apiserver/app/server.go

@@ -110,30 +110,39 @@ func Run(runOptions *options.ServerRunOptions, stopCh <-chan struct{}) error {
 	// To help debugging, immediately log version
 	glog.Infof("Version: %+v", version.Get())
 
-	nodeTunneler, proxyTransport, err := CreateNodeDialer(runOptions)
+	server, err := createServerChain(runOptions, stopCh)
 	if err != nil {
 		return err
 	}
 
+	return server.PrepareRun().Run(stopCh)
+}
+
+// createServerChain creates the apiservers connected via delegation.
+func createServerChain(runOptions *options.ServerRunOptions, stopCh <-chan struct{}) (*genericapiserver.GenericAPIServer, error) {
+	nodeTunneler, proxyTransport, err := CreateNodeDialer(runOptions)
+	if err != nil {
+		return nil, err
+	}
 	kubeAPIServerConfig, sharedInformers, versionedInformers, insecureServingOptions, serviceResolver, err := CreateKubeAPIServerConfig(runOptions, nodeTunneler, proxyTransport)
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	// TPRs are enabled and not yet beta, since this these are the successor, they fall under the same enablement rule
 	// If additional API servers are added, they should be gated.
 	apiExtensionsConfig, err := createAPIExtensionsConfig(*kubeAPIServerConfig.GenericConfig, runOptions)
 	if err != nil {
-		return err
+		return nil, err
 	}
 	apiExtensionsServer, err := createAPIExtensionsServer(apiExtensionsConfig, genericapiserver.EmptyDelegate)
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	kubeAPIServer, err := CreateKubeAPIServer(kubeAPIServerConfig, apiExtensionsServer.GenericAPIServer, sharedInformers)
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	// if we're starting up a hacked up version of this API server for a weird test case,
@@ -142,11 +151,11 @@ func Run(runOptions *options.ServerRunOptions, stopCh <-chan struct{}) error {
 		if insecureServingOptions != nil {
 			insecureHandlerChain := kubeserver.BuildInsecureHandlerChain(kubeAPIServer.GenericAPIServer.UnprotectedHandler(), kubeAPIServerConfig.GenericConfig)
 			if err := kubeserver.NonBlockingRun(insecureServingOptions, insecureHandlerChain, stopCh); err != nil {
-				return err
+				return nil, err
 			}
 		}
 
-		return kubeAPIServer.GenericAPIServer.PrepareRun().Run(stopCh)
+		return kubeAPIServer.GenericAPIServer, nil
 	}
 
 	// otherwise go down the normal path of standing the aggregator up in front of the API server
@@ -156,24 +165,24 @@ func Run(runOptions *options.ServerRunOptions, stopCh <-chan struct{}) error {
 	// aggregator comes last in the chain
 	aggregatorConfig, err := createAggregatorConfig(*kubeAPIServerConfig.GenericConfig, runOptions, versionedInformers, serviceResolver, proxyTransport)
 	if err != nil {
-		return err
+		return nil, err
 	}
 	aggregatorConfig.ProxyTransport = proxyTransport
 	aggregatorConfig.ServiceResolver = serviceResolver
 	aggregatorServer, err := createAggregatorServer(aggregatorConfig, kubeAPIServer.GenericAPIServer, apiExtensionsServer.Informers)
 	if err != nil {
 		// we don't need special handling for innerStopCh because the aggregator server doesn't create any go routines
-		return err
+		return nil, err
 	}
 
 	if insecureServingOptions != nil {
 		insecureHandlerChain := kubeserver.BuildInsecureHandlerChain(aggregatorServer.GenericAPIServer.UnprotectedHandler(), kubeAPIServerConfig.GenericConfig)
 		if err := kubeserver.NonBlockingRun(insecureServingOptions, insecureHandlerChain, stopCh); err != nil {
-			return err
+			return nil, err
 		}
 	}
 
-	return aggregatorServer.GenericAPIServer.PrepareRun().Run(stopCh)
+	return aggregatorServer.GenericAPIServer, nil
 }
 
 // CreateKubeAPIServer creates and wires a workable kube-apiserver