Docker VerneMQ

An Alpine Linux image running VerneMQ MQTT broker (https://vernemq.com), supporting swarm mode.

Env var

name	description	default
SELF_IP	The container IP. It will be discovered in swarm mode.	127.0.0.1
SERVICE_NAME	The swarm service name, used to discover other nodes. Cluster mode is disabled if this variable is empty	""
DISCOVERY_NAME	The DNS name to resolve to fetch a list of all nodes. Only used in cluster mode.	"tasks.${SERVICE_NAME}"
MIN_NODES_SIZE	The minimum number of node to wait before starting when running in cluster mode	3

Exploitation

The vmq-admin utility is located in /usr/share/vernemq/bin/vmq-admin, so you can run:

#!/bin/bash

id=$(docker ps | grep "jbonachera/vernemq:" | awk '{ print $1 }')
docker exec -it $id vmq-admin  $@

Testing with docker-compose

edit the docker-compose.yml to add the environment variable DISCOVERY_NAME="vernemq"

docker-compose up --scale vernemq=3

A cluster of 3 nodes should be started, and MQTT service should be exposed on a random port on localhost.

show the cluster nodes

docker-compose exec vernemq vmq-admin cluster show

subscribe to a topic running

mosquitto_sub -h localhost --host 127.0.0.1 --port $(docker-compose port vernemq 1883 | cut -d : -f 2) -d -t devices/+/temperature/degrees

Testing with Swarm mode

docker swarm init
docker stack deploy -c docker-compose.yml mqtt