This is a slight modification that is less flexible, but is adapted to the usecase in mailu. If you wish to deploy mailu behind a traefik, you face many problems. One of these is that you need to get the certificates into mailu in a very defined manner. This will copy the certificate for the Main:-domain given in the DOMAIN-environment onto output.

If your output happens to be mailu-front-/certs, the certificate-watcher in the front-container will catch it and reload nginx. This works for mailu TLS_FLAVOR=[mail, cert]

  certdumper:
    restart: always
    image: Mailu/traefik-certdumper:$VERSION
    environment:
      - DOMAIN=$DOMAIN
    volumes:
      # your traefik data-volume is probably declared outside of the mailu composefile
      - /data/traefik:/traefik
      - $ROOT/certs/:/output/