Websockets problem when simulatenous connections

[Frco. Javier Rial]

Hi all

I'm having this same exact problem as describe this
https://stackoverflow.com/questions/54374533/guacamole-multiple-simultaneous-vnc-connections-over-websocket-close-each-other

I've built my own guacamole application, just like this (I'm omitting the
keycloak integration for authentication that I have and some minor details)
My app has an angular frontend, a backend in Java and a docker server.

Basically, when an user connects to the httptunnel/websocket, the backend
in java connects to the docker server (using docker api) to setup and run
an specific docker image for this user. This image contains the guacd
daemon running inside

Just to clarify, if I use HTTPTunnel, it works fine. I have my own
implementation for the httptunnel in the java backend and works without any
issues handling several connected users, but, with the poor performance
provided by the httptunnel

While using the websocket implementation in java, I have the mentioned
problem in stackoverflow

My implementation is as follows (minimal code provided here)
@ServerEndpoint(value = "/webSocket", configurator =
CustomSpringConfigurator.class)
@Component
public class WebSocketTunnel extends GuacamoleWebSocketTunnelEndpoint {

    @Autowired
    private DefaultConfiguration defaultConfiguration;

    @Autowired
    private ContainerService containerService;

    @Autowired
    private UserUtil userUtil;

    @Override
    protected GuacamoleTunnel createTunnel(Session session, EndpointConfig
endpointConfig) throws GuacamoleException {

        try {
            GuacamoleSocket socket = null;
   containerService.getContainer(principalTO.get().getIdUser());
            socket = new ConfiguredGuacamoleSocket(
                new InetGuacamoleSocket(containerTO.get().getHost(),

Integer.parseInt(containerTO.get().getPort())),configuration);
                    }
                }
            GuacamoleTunnel tunnel = new SimpleGuacamoleTunnel(socket);
            return tunnel;
        } catch (Exception e) {
            log.error(e);
        }
        return null;
    }

    .....
}


The angular frontend just connects to the java backend endpoint that
creates the websocket and gets the tunnel provided.

The socket is configured against the IP/port of the running docker image on
the docker server
It returns the websocket and everything works fine with one connected user.
Each running docker image has it's own ip and different ports binded
externally for the guacd daemon (internally all guacd listen on the same
port 4822)

But as soon as any other user tries to connect, the websocket is closed

This is logged in the java backend

Exception in thread "Thread-2" java.lang.IllegalStateException: The
WebSocket session [1] has been closed and no method (apart from close())
may be called on a closed session
at org.apache.tomcat.websocket.WsSession.checkState(WsSession.java:1082)
at
org.apache.tomcat.websocket.WsSession.getUserProperties(WsSession.java:990)
at
org.apache.tomcat.websocket.WsRemoteEndpointImplBase.getBlockingSendTimeout(WsRemoteEndpointImplBase.java:533)
at
org.apache.tomcat.websocket.WsRemoteEndpointImplBase.getTimeoutExpiry(WsRemoteEndpointImplBase.java:270)
at
org.apache.tomcat.websocket.WsRemoteEndpointImplBase.sendMessageBlock(WsRemoteEndpointImplBase.java:244)
at
org.apache.tomcat.websocket.WsRemoteEndpointImplBase.sendString(WsRemoteEndpointImplBase.java:195)
at
org.apache.tomcat.websocket.WsRemoteEndpointBasic.sendText(WsRemoteEndpointBasic.java:37)
at
org.apache.guacamole.websocket.GuacamoleWebSocketTunnelEndpoint.sendInstruction(GuacamoleWebSocketTunnelEndpoint.java:152)
at
org.apache.guacamole.websocket.GuacamoleWebSocketTunnelEndpoint.access$200(GuacamoleWebSocketTunnelEndpoint.java:53)
at
org.apache.guacamole.websocket.GuacamoleWebSocketTunnelEndpoint$2.run(GuacamoleWebSocketTunnelEndpoint.java:253)


Can someone give me any hint about the websocket implementation ??
Please, feel free to ask me for anything