Flask-SocketIO: Emit socket to all client outside of context

Question

With Flask-MQTT and Flask-SocketIO, I'm trying to emit a socket message outside from the Flask-SocketIO event context to all connected clients, upon reception of an MQTT message. Yet, when doing so, the messages never seem to reach the clients.

It appears this has been a long known issue, but using app.app_context() does not seem to work for me either.

Here is what I have for now:

app = Flask(__name__)

[app.config ...]

cors = CORS(app,resources={ "/*": {"origins":"*"} })
mqtt = Mqtt(app)
socketio = SocketIO(app)

[...]

@mqtt.on_message()
def handle_mqtt_message(client, userdata, message):
    with app.app_context():
        # Send socket to all connected clients.
        # Not working for some reasons...
        socketio.emit("mqtt_message")

@socketio.on("connect")
def handle_socketio_connect():
    # This works.
    emit("hello")

if __name__ == "__main__":
    socketio.run(app, [...] )

Packages versions:

Flask-SocketIO, 3.0.1
Flask-MQTT, 1.0.3
Eventlet, 0.23.0

Does it work if you uninstall eventlet? I suspect MQTT and Eventlet aren't compatible. If uninstalling eventlet makes your app work, I suggest you then try installing it back and adding monkey patching to see if that helps (see http://eventlet.net/doc/patching.html#monkeypatching-the-standard-library) — Miguel Grinberg, Jul 07 '18 at 14:42

Flask-SocketIO: Emit socket to all client outside of context

0 Answers0