func NewHandler(t *http.Transport, urlsFunc GetProxyURLs, failureWait time.Duration, refreshInterval time.Duration) http.Handler {
	if t.TLSClientConfig != nil {
		// Enable http2, see Issue 5033.
		err := http2.ConfigureTransport(t)
		if err != nil {
			plog.Infof("Error enabling Transport HTTP/2 support: %v", err)
		}
	}

	p := &reverseProxy{
		director:  newDirector(urlsFunc, failureWait, refreshInterval),
		transport: t,
	}

	mux := http.NewServeMux()
	mux.Handle("/", p)
	mux.HandleFunc("/v2/config/local/proxy", p.configHandler)

	return mux
}
func NewHandler(t *http.Transport, urlsFunc GetProxyURLs, failureWait time.Duration, refreshInterval time.Duration) http.Handler {
	if t.TLSClientConfig != nil {
		// Enable http2, see Issue 5033.
		err := http2.ConfigureTransport(t)
		if err != nil {
			plog.Infof("Error enabling Transport HTTP/2 support: %v", err)
		}
	}

	p := &reverseProxy{
		director:  newDirector(urlsFunc, failureWait, refreshInterval),
		transport: t,
	}

	mux := http.NewServeMux()
	mux.Handle("/", p)
	mux.HandleFunc("/v2/config/local/proxy", p.configHandler)

	return mux
}
// NewHandler creates a new HTTP handler, listening on the given transport,
// which will proxy requests to an etcd cluster.
// The handler will periodically update its view of the cluster.