MQTTGateway for Prometheus

A project that subscribes to MQTT queues and published prometheus metrics. This Project is forked from inuits/mqttgateway. It is designed to run in docker, especially in docker-compose.

Prerequisites

docker and docker-compose should be installed correctly.

Installation

git clone https://github.com/LarsTi/mqttgateway.git
cd mqttgateway
docker-compose up --build -d

How does it work?

mqttgateway will connect to the MQTT broker at MQTT_BROKER_ADDRESS and listen to the topics specified by MQTT_TOPIC.

The format for the topics is as follow:

prefix/LABEL1/VALUE1/LABEL2/VALUE2/NAME

A topic prometheus/job/ESP8266/instance/livingroom/temperature_celcius would be converted to a metric temperature_celcius{job="ESP8266",instance="livingroom"}.

If labelnames differ for a same metric, then we invalidate existing metrics and only keep new ones. Then we issue a warning in the logs. You should avoid it.

Two other metrics are published, for each metric:

• mqtt_NAME_last_pushed_timestamp, the last time NAME metric has been pushed (unix time, in seconds)
• mqtt_NAME_push_total, the number of times a metric has been pushed

Available Environmentvariables:

WEB_TELEMETRY_PORT defaults to 9337 and is supposed to be the port where prometheus can scrape the metrics

WEB_TELEMETRY_PATH defaults to /metrics and is supposed to be the endpoint where prometheus can scrape

MQTT_BROKER_ADDRESS defaults to tcp://localhost:1883 and is supposed to be the address to a MQTT-Broker

MQTT_TOPIC defaults to prometheus/# and is the topic which will be subscribed

MQTT_PREFIX defaults to prometheus and is the prefix which will be cut (see above)

MQTT_CLIENT_ID defaults to mqtt2prometheus and is the client ID which is used to identify to mqtt (not the username!)

Not yet done

The Authentication towards the MQTT-Broker is not yet done and not planned. Due to my setup, the MQTT-Broker is in a seperated VLAN and therefore i do not use authentications on the broker.

Example

This example is also in docker-compose.yaml

version: '3.3'

services:
        mqttgateway:
                build: .
                restart: unless-stopped

networks:
        default:

A note about the prometheus config

If you use job and instance labels, please refer to the pushgateway exporter documentation.

TL;DR: you should set honor_labels: true in the scrape config.