# A full runthrough of the upgrade shape pgs3 exists for:
#
#   primary --archive--> [archive volume] --> pgs3 --pgoutput--> replica
#
# The two networks are the point. pgs3 sits only on `downstream`, so it has no
# route to the primary at all: the replica's catch-up provably comes from
# archived WAL rather than from a live connection to the source.
#
#   docker compose -f docker/compose.yaml up --build \
#     --abort-on-container-exit --exit-code-from demo

name: pgs3-demo

x-postgres: &postgres
  image: postgres:18
  environment:
    POSTGRES_PASSWORD: postgres
    POSTGRES_HOST_AUTH_METHOD: trust
  healthcheck:
    test: ["CMD-SHELL", "pg_isready -U postgres"]
    interval: 1s
    timeout: 3s
    retries: 30

services:
  # Gives postgres ownership of the shared volumes before anything starts.
  init:
    image: postgres:18
    user: root
    command: >-
      sh -c "mkdir -p /archive /state &&
             chown -R postgres:postgres /archive /state &&
             echo 'init: archive and state ready'"
    volumes:
      - archive:/archive
      - state:/state

  primary:
    <<: *postgres
    depends_on:
      init: {condition: service_completed_successfully}
    command:
      - postgres
      - -c
      - wal_level=logical
      - -c
      - max_replication_slots=8
      - -c
      - max_wal_senders=8
      - -c
      - wal_compression=pglz
      - -c
      - archive_mode=on
      # The archive is the only thing pgs3 ever reads.
      - -c
      - archive_command=test ! -f /archive/%f && cp %p /archive/%f
      # Roll a segment even when idle, so the archive keeps up with the demo.
      - -c
      - archive_timeout=10s
    volumes:
      - archive:/archive
    networks: [upstream]

  # Stands in for the freshly-upgraded replica.
  replica:
    <<: *postgres
    depends_on:
      init: {condition: service_completed_successfully}
    command:
      - postgres
      - -c
      - max_logical_replication_workers=8
      - -c
      - max_worker_processes=16
    # On both networks: it subscribes to the primary first to establish T0,
    # then is repointed at pgs3.
    networks: [upstream, downstream]
    ports:
      - "55433:5432"

  pgs3:
    build:
      context: ..
      dockerfile: docker/Dockerfile
    depends_on:
      init: {condition: service_completed_successfully}
    volumes:
      - archive:/archive:ro
      - state:/state
    # Only `downstream`. There is no route from here to the primary.
    networks: [downstream]
    ports:
      - "55439:5439"
    restart: on-failure

  demo:
    image: postgres:18
    depends_on:
      primary: {condition: service_healthy}
      replica: {condition: service_healthy}
    environment:
      PGUSER: postgres
      PGPASSWORD: postgres
    volumes:
      - state:/state
      - archive:/archive:ro
      - ./demo.sh:/demo.sh:ro
      - ../sql:/sql:ro
      - ../scripts:/scripts:ro
    entrypoint: ["/bin/bash", "/demo.sh"]
    networks: [upstream, downstream]

networks:
  upstream:
  downstream:

volumes:
  archive:
  state: