halkyon/deploy/compose.yaml

# The Halkyon Learn instance: Caddy in front, the Serverpod server, PostgreSQL, and
# the dictionaries kept current beside them.
#
#   cd deploy
#   cp .env.example .env && chmod 600 .env   # then fill in the secrets
#   docker compose up -d --build
#
# Only Caddy publishes ports. Docker opens published ports directly in the kernel's
# packet filter, past ufw, and the Serverpod server listens on every interface, so the
# server and Postgres publish nothing: they're reachable only inside this project's
# network, where Caddy finds the server by its service name.

name: halkyon-learn

# Logs go to the host's journal, whose size and age limits apply (journald.conf).
x-logging: &logging
  driver: journald

services:
  caddy:
    image: caddy:2
    restart: unless-stopped
    ports:
      - "80:80"
      - "443:443"
      - "443:443/udp" # HTTP/3
    environment:
      # `learn.halkyon.eu` on sahaquiel (automatic Let's Encrypt certificate);
      # `http://localhost` for the local rehearsal (plain HTTP, no certificate).
      DOMAIN: ${DOMAIN:?set DOMAIN in deploy/.env}
    volumes:
      - ./Caddyfile:/etc/caddy/Caddyfile:ro
      - caddy_data:/data # certificates: must survive restarts (rate limits)
      - caddy_config:/config
    depends_on:
      - server
    logging: *logging

  server:
    build:
      context: ..
      dockerfile: halkyon_learn_server/Dockerfile
    image: halkyon-learn-server
    restart: unless-stopped
    # Applies pending migrations at every start, then serves. One instance only, so
    # no two servers ever migrate at once. (On learn.halkyon.eu, deploy/redeploy.sh has
    # applied them in a run of their own before, so nothing is left to do here.)
    command: ["--apply-migrations"]
    environment:
      SERVERPOD_DATABASE_PASSWORD: ${POSTGRES_PASSWORD:?set POSTGRES_PASSWORD in deploy/.env}
      SERVERPOD_PASSWORD_serverSideSessionKeyHashPepper: ${SESSION_KEY_HASH_PEPPER:?set SESSION_KEY_HASH_PEPPER in deploy/.env}
      # GitHub sign-in, only with this instance's GitHub OAuth app; empty: off.
      SERVERPOD_PASSWORD_githubClientId: ${GITHUB_CLIENT_ID:-}
      SERVERPOD_PASSWORD_githubClientSecret: ${GITHUB_CLIENT_SECRET:-}
      # Where the source of what this instance runs is; empty: the project's.
      SOURCE_URL: ${SOURCE_URL:-}
      # How much room people's files may take, in MiB; empty: the defaults.
      FILE_LIMIT_ANONYMOUS_MB: ${FILE_LIMIT_ANONYMOUS_MB:-}
      FILE_LIMIT_IDENTIFIED_MB: ${FILE_LIMIT_IDENTIFIED_MB:-}
      FILE_LIMIT_INSTANCE_MB: ${FILE_LIMIT_INSTANCE_MB:-}
    # The dictionary files it loads at start and rereads daily, those that changed
    # (see the server's README): those the dictionaries service keeps current, read
    # only. To supply files yourself instead, remove that service and mount
    # ./dictionaries here (`- ./dictionaries:/app/dictionaries:ro`).
    volumes:
      - dictionaries:/app/dictionaries:ro
    depends_on:
      postgres:
        condition: service_healthy
    logging: *logging

  # Keeps the dictionary files current from EDRDG's files of the day, once they are a
  # week old (EDRDG's licence asks it of servers showing its dictionaries at least
  # monthly; the curator's README): in a container of its own, the curator never in
  # the server's image or process. It only downloads (some 25 MB a week) and writes
  # into the volume; the files are never backed up, as they can be had again.
  dictionaries:
    build:
      context: ..
      dockerfile: halkyon_learn_curator/Dockerfile
    image: halkyon-learn-dictionaries
    restart: unless-stopped
    # Docker's stop signal reaches the curator through a small init.
    init: true
    # A conversion takes some 400 MB for a minute a week.
    mem_limit: 1g
    volumes:
      - dictionaries:/dictionaries
    logging: *logging

  postgres:
    image: postgres:16
    restart: unless-stopped
    # The server's session is UTC anyway (the driver sets it); this makes the
    # database's own default UTC too, for psql, COPY loads and future sidecars.
    command: ["postgres", "-c", "timezone=UTC", "-c", "log_timezone=UTC"]
    environment:
      POSTGRES_USER: halkyon_learn
      POSTGRES_DB: halkyon_learn
      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:?set POSTGRES_PASSWORD in deploy/.env}
    volumes:
      - postgres_data:/var/lib/postgresql/data
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U halkyon_learn -d halkyon_learn"]
      interval: 5s
      timeout: 5s
      retries: 12
    logging: *logging

volumes:
  caddy_data:
  caddy_config:
  dictionaries:
  postgres_data: