This exporter is an analog to the Prometheus Pushgateway. Clients can push metrics via MQTT to an MQTT Broker. This exporter subscribes to the broker and publish the received messages as prometheus metrics. I wrote this exporter to publish metrics from small embedded sensors based on the NodeMCU to prometheus. The used arduino scetch can be found in the dht22tomqtt repository.
This exporter makes some assumptions about the message format and MQTT topics. This exporter assumes that each
client publish the metrics into a dedicated topic. The last level topic becomes the sensor label in prometheus.
This exporter assume that the message are JSON objects with only float fields. The golang type for the messages is:
type MQTTPayload map[string]float64For example the message
{"temperature":23.20,"humidity":51.60,"heat_index":22.92}published to the MQTT topic devices/me/livingroom becomes the following prometheus metrics:
temperature{sensor="livingroom"} 23.2
heat_index{sensor="livingroom"} 22.92
humidity{sensor="livingroom"} 51.6
To build the exporter run:
make buildTo start the public available image run:
docker run -it -v "$(pwd)/config.yaml:/config.yaml" -p 8002:8002 hikhvar/mqtt2prometheus:latest To build a docker container with the mqtt2prometheus exporter included run:
make containerTo run the container with a given config file:
docker run -it -v "$(pwd)/config.yaml:/config.yaml" -p 8002:8002 mqtt2prometheus:latest The exporter can be configured via command line and config file.
Available command line flags:
Usage of ./mqtt2prometheus.linux_amd64:
-config string
config file (default "config.yaml")
-listen-address string
listen address for HTTP server used to expose metrics
-listen-port string
HTTP port used to expose metrics (default "8002")
The config file can look like this:
# Settings for the MQTT Client. Currently only these three are supported
mqtt:
# The MQTT broker to connect to
server: tcp:https://127.0.0.1:1883
# The Topic path to subscripe to. Actually this will become `$topic_path/+`
topic_path: v1/devices/me
# The MQTT QoS level
qos: 0
cache:
# Timeout. Each received metric will be presented for this time if no update is send via MQTT
timeout: 2min
# This is a list of valid metrics. Only metrics listed here will be exported
metrics:
# The name of the metric in prometheus
- prom_name: temperature
# The name of the metric in a MQTT JSON message
mqtt_name: temperature
# The prometheus help text for this metric
help: DHT22 temperature reading
# The prometheus type for this metric. Valid values are: "gauge" and "counter"
type: gauge
# A map of string to string for constant labels. This labels will be attached to every prometheus metric
const_labels:
sensor_type: dht22
# The name of the metric in prometheus
- prom_name: humidity
# The name of the metric in a MQTT JSON message
mqtt_name: humidity
# The prometheus help text for this metric
help: DHT22 humidity reading
# The prometheus type for this metric. Valid values are: "gauge" and "counter"
type: gauge
# A map of string to string for constant labels. This labels will be attached to every prometheus metric
const_labels:
sensor_type: dht22
# The name of the metric in prometheus
- prom_name: heat_index
# The name of the metric in a MQTT JSON message
mqtt_name: heat_index
# The prometheus help text for this metric
help: DHT22 heatIndex calculation
# The prometheus type for this metric. Valid values are: "gauge" and "counter"
type: gauge
# A map of string to string for constant labels. This labels will be attached to every prometheus metric
const_labels:
sensor_type: dht22%