mqtt_prometheus.py

from flask import Flask
from flask_mqtt import Mqtt

def create_app():
    app = Flask(__name__)
    app.config['MQTT_BROKER_URL'] = 'mosquito.lanarama.local'  # use the free broker from HIVEMQ
    app.config['MQTT_BROKER_PORT'] = 1883  # default port for non-tls connection
    app.config['MQTT_USERNAME'] = ''  # set the username here if you need authentication for the broker
    app.config['MQTT_PASSWORD'] = ''  # set the password here if the broker demands authentication
    app.config['MQTT_KEEPALIVE'] = 5  # set the time interval for sending a ping to the broker to 5 seconds
    app.config['MQTT_TLS_ENABLED'] = False  # set TLS to disabled for testing purposes
    app.mqtt_values = {}

    mqtt = Mqtt(app)

    @mqtt.on_connect()
    def handle_mqtt_connect(*args):
        # Can be multiple
        mqtt.subscribe("topic/to/subscribe/to")

    @mqtt.on_message()
    def handle_mqtt_message(client, userdata, message):
        app.mqtt_values[message.topic] = float(message.payload.decode())

    @app.route("/metrics")
    def get_metrics():
        buf = ""
        for topic, data in app.mqtt_values:
            for k, v in data:
                # Builds a strink like:
                #
                # kuehlschrank_temperatur{topic="test"} 22.1
                buf += f"{k.replace("/", "_")}{{topic=\"{ topic }\"}} {v}" \n
        return buf
    return app

if __name__ == "__main__":
    app = create_app()
    app.run(host="::", port="9080")