How to fix docker emqx_ctl Node '[email protected]' not responding to pings.

Problem:

When trying to run emqx_ctl in a dockerized emqx setup using a command like

docker-compose exec emqx ./bin/emqx status

you see an error message like

Node '[email protected]' not responding to pings.
/opt/emqx/bin/emqx: line 41: die: command not found

Solution

The problem here is that emqx_ctl is trying to connect to the IP address for node1.emqx.mydomain.com but that IP address does not point to the IP address for the docker container (maybe it’s the public IP address for your server?)

The solution here is to create a network alias within docker/docker-compose so that the Docker DNS system resolves node1.emqx.mydomain.com to the internal IP address of the container.

For example, in docker-compose, you can create your network using

networks:
  emqx:
    driver: bridge

and then configure the alias for the container using

services:
  emqx:
    image: emqx:4.4.4
    environment:
      - "EMQX_NAME=emqx"
      - "EMQX_HOST=node1.emqx.mydomain.com"
      - "EMQX_LOADED_PLUGINS=emqx_recon,emqx_retainer,emqx_management,emqx_dashboard"
    ports:
      - 18083:18083
      - 1883:1883
    volumes:
      - ./emqx_data:/opt/emqx/data
      - ./emqx_log:/opt/emqx/log
    networks:
      emqx:
        aliases:
          - "node1.emqx.mydomain.com"