gistfile1.scala

object RedirectFilter extends SimpleFilter[HttpRequest, HttpResponse] {

  def apply(req: HttpRequest, serv: Service[HttpRequest, HttpResponse] = {
    serv(req)
      .flatMap { res =>
         if(res.statusCode == 302) { // Obviously, you can handle 301 and 307 as well
           val uri = res.headers.get("Location")
           // You'll want to check if uri is to the same host.
           // You'll want to copy all of req (headers, body, etc) and only replace uri, this is incomplete:
           val redirect = RequestBuilder().create.uri(uri).buildGet
           serv(redirect)
         } else Future.const(res)
      }
  }

}