docker-compose.migration.yml

# One-shot migration overlay: Postgres 9.6 → 15.
#
# Used together with the main docker-compose.yml via:
#   docker compose -f docker-compose.yml -f docker-compose.migration.yml up ...
#
# Orchestrated by scripts/migrate-postgres.sh — don't run by hand unless you
# know what you're doing. The flow:
#   prep-migration  → renames data/dbdata to data/dbdata-old (idempotent)
#   postgres-old    → boots postgres 9.6 on the renamed data
#   migrator        → pg_dump from 9.6 and psql restore into 15
#                     (the postgres service from the main compose, which
#                     starts on a fresh empty data/dbdata)
#
# After the migrator exits 0, --abort-on-container-exit stops everything.
# Bring the stack back up with `docker compose up -d` (no -f flag).

services:
  prep-migration:
    image: alpine:3.20
    volumes:
      - ./data:/data
    command: >
      sh -c '
      if [ ! -d /data/dbdata-old ] && [ -d /data/dbdata ]; then
        mv /data/dbdata /data/dbdata-old &&
        mkdir /data/dbdata &&
        echo "==> Renamed data/dbdata to data/dbdata-old; created empty data/dbdata for postgres 15";
      else
        echo "==> Pre-migration setup already in place (dbdata-old exists or dbdata missing); skipping";
      fi
      '

  postgres-old:
    image: postgres:9.6
    environment:
      POSTGRES_PASSWORD: '${DATABASE_PASS}'
      POSTGRES_USER: '${DATABASE_NAME}'
      POSTGRES_DB: '${DATABASE_USER}'
    volumes:
      - ./data/dbdata-old:/var/lib/postgresql/data
    depends_on:
      prep-migration:
        condition: service_completed_successfully
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U $${POSTGRES_USER}"]
      interval: 5s
      timeout: 3s
      retries: 20
      start_period: 10s
    networks:
      red:

  migrator:
    image: postgres:15
    environment:
      PGPASSWORD: '${DATABASE_PASS}'
      PGUSER: '${DATABASE_NAME}'
    depends_on:
      postgres-old:
        condition: service_healthy
      postgres:
        condition: service_healthy
    command: >
      bash -c "
      set -e;
      echo '==> Dumping from postgres 9.6 (postgres-old)...';
      pg_dump --clean --if-exists -h postgres-old -d '${DATABASE_USER}' > /tmp/dump.sql;
      echo '==> Restoring into postgres 15 (postgres)...';
      psql -h postgres -d '${DATABASE_USER}' -v ON_ERROR_STOP=1 -f /tmp/dump.sql;
      echo '==> Migration complete!';
      "
    networks:
      red: