# Overlay that swaps the in-process queues for durable RabbitMQ ones.
#
#   docker compose up                                                  # channels
#   docker compose -f docker-compose.yml -f docker-compose.rabbitmq.yml up
#
# The base file is left alone deliberately: `docker compose up` still brings up
# exactly what it always did, so neither backend is the awkward one to run.
#
# What the broker changes: a job stays unacked until its handler commits, so a
# restart resumes each file at the stage it had reached instead of re-driving
# everything in spool/ from stage 1. See "Queue backends" in the README for the
# guarantees, and for the deliberate holes.

services:
  rabbitmq:
    image: rabbitmq:4-management
    environment:
      # The built-in guest/guest only authenticates over loopback, so it cannot
      # work across the compose network. Override these for anything real; they
      # are here so the stack comes up with one command, not as a credential.
      RABBITMQ_DEFAULT_USER: "fileserver"
      RABBITMQ_DEFAULT_PASS: "fileserver"
    ports:
      # 5672 is published so you can run the server on the host
      # (`julia --project=. -t auto bin/server.jl`) against this broker; 15672 is
      # the management UI, which is most of the reason to run a broker you can
      # look at. Neither needs publishing for the composed server to work.
      - "5672:5672"
      - "15672:15672"
    volumes:
      # Durable queues and persistent messages are only as durable as what they
      # are written to: without this, `docker compose down` discards the backlog
      # the acks exist to protect.
      - rabbitmq-data:/var/lib/rabbitmq
    healthcheck:
      test: ["CMD", "rabbitmq-diagnostics", "-q", "ping"]
      interval: 10s
      timeout: 5s
      retries: 12
      start_period: 30s
    restart: unless-stopped

  file-server:
    environment:
      FS_QUEUE_BACKEND: "rabbitmq"
      FS_AMQP_URL: "amqp://fileserver:fileserver@rabbitmq:5672/"
    depends_on:
      rabbitmq:
        # The server retries a broker that isn't up yet (AMQP_CONNECT_RETRY_SECONDS),
        # so this gate is belt-and-braces rather than load-bearing — but it keeps
        # a cold start quiet instead of a screenful of retry lines.
        condition: service_healthy

volumes:
  rabbitmq-data: