Logging request duration, path, status code using Akka HTTP

log.scala

  val rejectionHandler = RejectionHandler.default
  def logDuration(inner: Route): Route = { ctx =>
    val start = System.currentTimeMillis()
    // handling rejections here so that we get proper status codes
    val innerRejectionsHandled = handleRejections(rejectionHandler)(inner)
    mapResponse { resp =>
      val d = System.currentTimeMillis() - start
      logger.info(s"[${resp.status.intValue()}] ${ctx.request.method.name} ${ctx.request.uri} took: ${d}ms")
      resp
    }(innerRejectionsHandled)(ctx)
  }

  // improved by @luksow
  val rejectionHandler = RejectionHandler.default
  val logDuration = extractRequestContext.flatMap { ctx =>
    val start = System.currentTimeMillis()
    // handling rejections here so that we get proper status codes
    mapResponse { resp =>
      val d = System.currentTimeMillis() - start
      logger.info(s"[${resp.status.intValue()}] ${ctx.request.method.name} ${ctx.request.uri} took: ${d}ms")
      resp
    } & handleRejections(rejectionHandler)
  }

new to akka http, how could I use extractClientIP in logDuration? thanks

update :
found here http://stackoverflow.com/a/36729869/851099