__init__.py

from flask_mqtt import Mqtt                     # MQTT using flask
from app.mqtt import mqtt_message_handler

def init_app(app):
    mqtt = Mqtt(app)

    @mqtt.on_connect()
    def handle_connect(client, userdata, flags, rc):
        mqtt.subscribe('owntracks/4009user/#')  #owntracks subscribing to mqtt

    @mqtt.on_message()
    def handle_mqtt_message(client, userdata, msg):
        mqtt_message_handler.getMsg(msg)