docker-workflows

# Docker Workflows Skill ## When to Activate Activate this skill when: - Creating Dockerfiles for applications - Setting up docker-compose environments - Containerizing Python/UV projects - Configuring multi-stage builds - Managing container secrets ## Quick Commands ```bash # Build image docker build -t my-app:latest . # Run container docker run -d -p 8000:8000 --name my-app my-app:latest # View logs docker logs -f my-app # Execute in container docker exec -it my-app bash # Stop and remove docker stop my-app && docker rm my-app # Clean up docker system prune -a ``` ## Basic Dockerfile (Python/UV) ```dockerfile FROM python:3.11-slim WORKDIR /app # Install UV COPY --from=ghcr.io/astral-sh/uv:latest /uv /usr/local/bin/uv # Copy dependency files (layer caching) COPY pyproject.toml uv.lock ./ # Install dependencies RUN uv sync --frozen --no-dev # Copy application COPY . . EXPOSE 8000 CMD ["uv", "run", "python", "main.py"] ``` ## Multi-Stage Build (Production) ```dockerfile # Stage 1: Builder FROM python:3.11-slim AS builder WORKDIR /app COPY --from=ghcr.io/astral-sh/uv:latest /uv /usr/local/bin/uv COPY pyproject.toml uv.lock ./ RUN uv sync --frozen --no-dev COPY . . # Stage 2: Runtime FROM python:3.11-slim WORKDIR /app # Create non-root user RUN useradd -m -u 1000 appuser && chown appuser:appuser /app # Copy from builder COPY --from=builder /app/.venv /app/.venv COPY --from=builder /app /app USER appuser ENV PATH="/app/.venv/bin:$PATH" EXPOSE 8000 CMD ["python", "main.py"] ``` ## .dockerignore ``` __pycache__/ *.pyc .git/ .env .venv/ venv/ *.log .DS_Store .pytest_cache/ tests/ docs/ *.md ``` ## Docker Compose (App + Database) ```yaml version: '3.8' services: app: build: . ports: - "8000:8000" environment: - DATABASE_URL=postgresql://user:password@db:5432/myapp depends_on: - db volumes: - ./app:/app # Development: live reload db: image: postgres:15-alpine environment: - POSTGRES_USER=user - POSTGRES_PASSWORD=password - POSTGRES_DB=myapp volumes: - postgres_data:/var/lib/postgresql/data ports: - "5432:5432" volumes: postgres_data: ``` ## Compose Commands ```bash # Start all services docker-compose up -d # View logs docker-compose logs -f app # Stop services docker-compose down # Rebuild and restart docker-compose up -d --build # Run command in service docker-compose exec app bash # Remove volumes (deletes data!) docker-compose down -v ``` ## Layer Caching Best Practice ```dockerfile # Good: Dependencies cached separately COPY pyproject.toml uv.lock ./ RUN uv sync --frozen --no-dev COPY . . # Bad: Cache invalidated on every code change COPY . . RUN uv sync --frozen --no-dev ``` ## Security Essentials ```dockerfile # Use official slim images FROM python:3.11-slim # Run as non-root RUN useradd -m -u 1000 appuser USER appuser # Don't include secrets in images # Use runtime environment variables instead ``` ## Runtime Secrets ```bash # Pass via environment docker run -e API_KEY=secret my-app # Use env file docker run --env-file .env.production my-app # With compose services: app: env_file: - .env.production ``` ## Volume Types ```bash # Named volume (data persistence) docker run -v postgres_data:/var/lib/postgresql/data postgres # Bind mount (development) docker run -v $(pwd)/app:/app my-app ``` ## Debugging ```bash # Interactive shell docker exec -it container_name bash # Real-time logs docker logs -f --tail 100 container_name # Inspect configuration docker inspect container_name # Resource usage docker stats container_name # Copy files docker cp container_name:/app/logs ./logs ``` ## Common Issues ### Container exits immediately ```bash docker logs container_name # Check for errors docker run -it app:v1 bash # Debug interactively ``` ### Can't connect to container ```bash docker ps # Check port mapping docker inspect container_name # Check network config ``` ### Out of disk space ```bash docker system df # Check usage docker system prune -a # Clean everything ``` ## Related Resources See `AgentUsage/docker_guide.md` for complete documentation including: - Advanced multi-stage patterns - Docker Compose variations - Production optimization - CI/CD integration