# Docker Compose file for PostgreSQL (Alpine)
#
# Usage:
#   docker compose up -d
#
# Environment variables (see .env.example for details):
#   POSTGRES_USER     - Superuser name (default: postgres)
#   POSTGRES_PASSWORD - Superuser password (default: postgres)
#   POSTGRES_DB       - Default database created on first start (default: postgres)

services:
  postgres:
    # For available image tags, see https://hub.docker.com/_/postgres
    image: postgres:18-alpine
    container_name: postgres
    environment:
      # Superuser name. Defaults to "postgres" if not set.
      - POSTGRES_USER=${POSTGRES_USER:-postgres}
      # Superuser password.
      # Default value is for local development only — change for production.
      - POSTGRES_PASSWORD=${POSTGRES_PASSWORD:-postgres}
      # Database created automatically on first start.
      # Defaults to the value of POSTGRES_USER if not set.
      - POSTGRES_DB=${POSTGRES_DB:-postgres}
    ports:
      # Map host port 5432 to container port 5432 (PostgreSQL default).
      - "5432:5432"
    volumes:
      # Persist data beyond container lifetime.
      - postgres_data:/var/lib/postgresql/data

volumes:
  postgres_data: