A wrapper for Spray's Http server that performs graceful shutdown. The server can be shutdown from the outside by calling the `stop()` method of from the service by sending a message: `context.parent ! Server.Stop`. These conversations helped me find a solution: [How to stop SimpleRoutingApp without getting an error](https://groups.google.com/d/…

1. spray-embedded-server

package org.qirx.browserTests

import scala.concurrent.Future
import scala.concurrent.Promise
import scala.concurrent.duration._
import scala.util.Try

import akka.actor.Actor
import akka.actor.ActorRef
import akka.actor.ActorSystem
import akka.actor.Props
import akka.io.IO
import akka.pattern.AskSupport
import akka.util.Timeout
import spray.can.Http

class Server(
  val host: String, val port: Int,
  serviceFactory:Props) {

  val system = ActorSystem("custom-server-system")

  val server = system.actorOf(
    Props(new ServerActor(serviceFactory)), "custom-server")

  def start(): Future[Server.Stopped] = {

    val closed = Promise[Server.Stopped]

    server ! Server.Start(host, port, closed.complete)

    implicit val ec = system.dispatcher

    closed.future.map { _ =>
      system.shutdown()
      system.awaitTermination()
    }
  }

  def stop(): Unit = if (!system.isTerminated) server ! Server.Stop
}

object Server {
  case class Start(host: String, port: Int, closedHandler: StopHandler)
  case object Stop

  type Stopped = Any
  type StopHandler = Try[Any] => Unit
}

class ServerActor(serviceFactory:Props) extends Actor with AskSupport {

  import context.system

  val service = context.actorOf(serviceFactory, "custom-server-service")

  def receive = stopped orElse unknown

  val unknown: Receive = {
    case unknown => println("ServerActor got unknown message: " + unknown)
  }

  var stopHandler: Server.StopHandler = null

  val stopped: Receive = {
    case Server.Start(host, port, handler) =>
      stopHandler = handler
      IO(Http) ! Http.Bind(service, host, port)
      become(starting)
  }

  def starting: Receive = {
    case Http.Bound(address) =>
      become(started(listener = sender))
  }

  def started(listener: ActorRef): Receive = {
    case Server.Stop =>
      listener ! Http.Unbind
      become(stopping)
  }

  def stopping: Receive = {
    case Http.Unbound =>
      implicit val timeout = Timeout(1.second)
      implicit val executor = system.dispatcher

      (IO(Http) ? Http.CloseAll).onComplete(stopHandler)
      stopHandler = null
      become(stopped)
  }

  def become(receive: Receive) = context.become(receive orElse unknown)
}

2. usage

def freePort = {
  val socket = new ServerSocket(0)
  val port = socket.getLocalPort
  socket.close()
  port
}

val server = new Server("localhost", freePort, akka.actor.Props(new Service))
val stopped = server.start()

def awaitStopped = {
  val timeout = 5.seconds
  try Await.ready(stopped, timeout)
  catch {
    case t: TimeoutException =>
      println("server not shutdown not called within " + timeout)
  }
}

try {
  code(server, driver)
  awaitStopped
} finally {
  server.stop()
  awaitStopped
}

3. dead-letters

It took me quite some time to figure out how to clear the log of dead letters. A few of those were:

Message [akka.dispatch.sysmsg.Terminate] from Actor[akka://test-server/user/IO-HTTP/listener-0/0#-1209567360] to Actor[akka://test-server/user/IO-HTTP/listener-0/0#-1209567360] was not delivered. [1] dead letters encountered. This logging can be turned off or adjusted with configuration settings 'akka.log-dead-letters' and 'akka.log-dead-letters-during-shutdown'.

Message [spray.io.TickGenerator$Tick$] from Actor[akka://test-server/user/IO-HTTP/listener-0#1862665875] to Actor[akka://test-server/user/IO-HTTP/listener-0#1862665875] was not delivered. [2] dead letters encountered. This logging can be turned off or adjusted with configuration settings 'akka.log-dead-letters' and 'akka.log-dead-letters-during-shutdown'.

Message [akka.dispatch.sysmsg.DeathWatchNotification] from Actor[akka://test-server/user/IO-HTTP/listener-0/0#761610642] to Actor[akka://test-server/user/IO-HTTP/listener-0/0#761610642] was not delivered. [1] dead letters encountered. This logging can be turned off or adjusted with configuration settings 'akka.log-dead-letters' and 'akka.log-dead-letters-during-shutdown'.

Message [akka.io.Tcp$Bound] from Actor[akka://test-server/user/IO-HTTP/listener-0#2088427833] to Actor[akka://test-server/deadLetters] was not delivered. [1] dead letters encountered. This logging can be turned off or adjusted with configuration settings 'akka.log-dead-letters' and 'akka.log-dead-letters-during-shutdown'.

Note that this does not work in all cases

Note that this does not do a "graceful shutdown" in the sense of allowing open requests to finish before terminating the server.

See [https://groups.google.com/forum/#!msg/spray-user/Sfh8x5yWibU/I1gDhwoULYsJ] for a discussion of how to achieve that.

It doesn't compile for me, line 30 for first gist snippet, for closed.complete parameter of Server.Start message: "Type mismatch, expected: Server.StopHandler, actual: (Try[Server.Stopped]) => closed.type"