int that port

src/app.py

@@ -37,6 +37,7 @@ if SENTRY_DSN:
 
 app = Flask(__name__)
 app.config['MQTT_BROKER_URL'] = MQTT_HOSTNAME
+MQTT_PORT = int(MQTT_PORT)
 app.config['MQTT_BROKER_PORT'] = MQTT_PORT
 app.config['MQTT_USERNAME'] = MQTT_USERNAME
 app.config['MQTT_PASSWORD'] = MQTT_PASSWORD