[question] How to create `aedes` broker cluster in Docker?

Start by reading the referenced aedes cluster example, the aedes-cli persistence and emitters documentation, and the supplied Docker Compose and dockerConfig.js examples. The issue does not identify a specific code change; done would require a decided, reproducible explanation of the supported clustering setup and its configuration.

First asked on SO.

I need to create a MQTT broker cluster. I want to use aedes (as I already use it, albeit without cluster) and Docker. Note that I have never created a cluster before (with nor without Docker).

Here I found official example how to create a cluster using aedes, but I was thinking about using aedes-cli Docker image.

Now, I have no idea which is better: should I create separate containers per broker (similarly to this question) or use mqemitter-redis/mqemitter-mongodb (as the aedes-cli docs suggest).

As for creating separate containers, I have no idea how to connect them.

As for using mqemitter-redis/mqemitter-mongodb, I have no idea how to setup them in the aedes-cli config file.

I have no need for data persistance accross broker cluster restarts. All I need is to distribute the messages accross multiple brokers in order to improve the runtime performance.

Below is a working, single-broker configuration.

• aedes.yml:

version: '3.7'
services:
  aedes:
    container_name: aedes
    image: moscajs/aedes:latest
    restart: always
    stop_signal: SIGINT
    network_mode: host
    command: -c /data/dockerConfig.js
    volumes:
      - /some/path/mqtt:/data
  mongo:
    container_name: mongo
    restart: always
    network_mode: host
    logging:
      driver: none
    image: mvertes/alpine-mongo
    volumes:
      - mongo_data:/data/db
    ports:
      - 27017:27017
volumes:
  mongo_data:
    name: mongo_data

• /some/path/mqtt/dockerConfig.js

module.exports = {
  protos: ['tcp', 'ws'],
  host: 'localhost',
  port: 1883,
  wsPort: 3000,
  wssPort: 4000,
  tlsPort: 8883,
  key: null,
  cert: null,
  rejectUnauthorized: true,
  credentials: null,
  brokerId: 'aedes',
  concurrency: 100,
  queueLimit: 42,
  maxClientsIdLength: 23,
  heartbeatInterval: 60000,
  connectTimeout: 30000,
  stats: false,
  statsInterval: 5000,
  mq: {
    name: 'mongodb',
    options: {
      url: 'mongodb://localhost:27017/aedes'
    }
  },
  verbose: false,
  veryVerbose: false,
  noPretty: false
}