如何将某些请求代理到另一台服务器？

I'd like my app to proxy requests received by a particular handler to another server. I've tried the following, but the request seems to just stall:

u, _ := url.Parse("http://localhost:3000")
proxy := httputil.NewSingleHostReverseProxy(u)

frontendHandler = func(ctx context.Context) {
    if err != nil {
        ctx.Writef("Error starting dev server %v.", err)
        return
    }

    proxy.ServeHTTP(ctx.ResponseWriter(), ctx.Request())
}

This is just meant to proxy frontend requests to the webpack dev server.