docker-compose.yml

version: '2.2'
services:
  # This is a daemon that listens to docker container events, and deletes stale UDP conntrack entries linked to the BF2 master server and master listing server
  # The most important deletion is on a healthcheck event (e.g. healthy), so ensure there is a healthcheck for the bf2 container
  # See: https://github.com/moby/moby/issues/8795
  delete-udp-conntrack:
    image: docker:20.10.20
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock:ro
    network_mode: host
    cap_add:
      - NET_ADMIN
    stop_signal: SIGKILL
    restart: always
    entrypoint:
      - /bin/sh
    command:
      - -c
      - |
          set -eu
          apk add --no-cache conntrack-tools
          docker events --filter type=container --filter event=create --filter event=start --filter event=health_status | while read; do
              conntrack -D -p udp --orig-port-dst 27900 || true
              conntrack -D -p udp --orig-port-dst 27910 || true
              conntrack -D -p udp --orig-port-src 58665 || true
          done