Docker Compose Setup

Docker Compose simplifies running the multi-stage images during development. The target option in the build configuration specifies which stage to build.

services:
  db:
    image: postgres:15-alpine
    environment:
      - POSTGRES_USER=user
      - POSTGRES_PASSWORD=password
      - POSTGRES_DB=timnology_db
    ports:
      - "5432:5432"
    volumes:
      - postgres_data:/var/lib/postgresql/data

  dev:
    build:
      context: .
      target: dev
    volumes:
      - ./src:/app/src  # Live reload support
    ports:
      - "8000:8000"
    environment:
      - POSTGRES_USER=user
      - POSTGRES_PASSWORD=password
      - POSTGRES_DB=timnology_db
      - POSTGRES_HOST=db
    depends_on:
      - db

  prod:
    build:
      context: .
      target: prod
    ports:
      - "8000:8000"
    environment:
      - POSTGRES_USER=user
      - POSTGRES_PASSWORD=password
      - POSTGRES_DB=timnology_db
      - POSTGRES_HOST=db
    depends_on:
      - db

volumes:
  postgres_data:

Configuration Details

Target stages — The target: dev and target: prod options tell Docker Compose which Dockerfile stage to build for each service.

Volume mount for live reload — The dev service mounts ./src:/app/src, mapping the local source directory into the container. Combined with FastAPI's dev mode, this enables automatic reloading when files change.

Service dependencies — Both application services declare depends_on: db, ensuring the database container starts first.

Running the Development Environment

docker compose up dev

This starts both the database and the dev service. The API becomes available at http://localhost:8000, with OpenAPI documentation at http://localhost:8000/docs.

Live Reload

With the source directory mounted, any changes to files in src/ are immediately visible to the container. FastAPI detects the file change and restarts the server automatically—no container rebuild required.