Allow override of kubeconfig dialer

cmd/kube-apiserver/app/server.go

@@ -30,6 +30,7 @@ import (
 	"github.com/spf13/cobra"
 
 	utilerrors "k8s.io/apimachinery/pkg/util/errors"
+	utilnet "k8s.io/apimachinery/pkg/util/net"
 	"k8s.io/apimachinery/pkg/util/sets"
 	utilwait "k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/apiserver/pkg/admission"
@@ -77,6 +78,10 @@ import (
 const etcdRetryLimit = 60
 const etcdRetryInterval = 1 * time.Second
 
+var (
+	DefaultProxyDialerFn utilnet.DialFunc
+)
+
 // NewAPIServerCommand creates a *cobra.Command object with default parameters
 func NewAPIServerCommand(stopCh <-chan struct{}) *cobra.Command {
 	s := options.NewServerRunOptions()
@@ -141,6 +146,7 @@ func Run(completeOptions completedServerRunOptions, stopCh <-chan struct{}) erro
 
 // CreateServerChain creates the apiservers connected via delegation.
 func CreateServerChain(completedOptions completedServerRunOptions, stopCh <-chan struct{}) (*master.Config, *genericapiserver.GenericAPIServer, error) {
+	completedOptions.KubeletConfig.Dial = DefaultProxyDialerFn
 
 	kubeAPIServerConfig, _, pluginInitializer, admissionPostStartHook, err := CreateKubeAPIServerConfig(completedOptions)
 	if err != nil {