web_socket_plugin & app engine

[Pacane]

Have you guys successfully deployed redstone with the web_socket_plugin to app engine managed vms?

I'got the the normal resources matching the end points, but it seems that on app engine (and even locally on gcloud) the requests never go to the methods

 @OnOpen()
  void onOpen(WebSocketSession session) {
    print("connection established");
  }

  @OnMessage()
  void onMessage(String message, WebSocketSession session) {
    print("message received: $message");
  }

This snippet works fine when I launch the server without gcloud. However, when I check the logs at startup I see that RedStone did its setup correctly (I suppose?)

configured websocket handler for /ws: socket_handler.WebSocketEndPoint

When querying the end point on my client I keep getting failed: Error during WebSocket handshake: Unexpected response code: 404