func HandleMetricsHealth(mux *http.ServeMux, srv etcdserver.ServerV2) {
	mux.Handle(PathMetrics, promhttp.Handler())
	mux.Handle(PathHealth, NewHealthHandler(func() Health { return checkHealth(srv) }))
}
func HandleMetricsHealth(mux *http.ServeMux, srv etcdserver.ServerV2) {
	mux.Handle(PathMetrics, promhttp.Handler())
	mux.Handle(PathHealth, NewHealthHandler(func() Health { return checkHealth(srv) }))
}
// HandleMetricsHealth registers metrics and health handlers.