multi-stage-dockerfile

par github

Construisez des Dockerfiles multi-étapes optimisés et sécurisés pour tout langage ou framework. Structure les builds avec des étapes de construction et d'exécution séparées, ne copiant que les artefacts nécessaires pour minimiser la taille finale de l'image et la surface d'attaque. Met l'accent sur l'optimisation du cache des couches en ordonnant les commandes des moins aux plus fréquemment modifiées, combiné avec .dockerignore et la consolidation des commandes. Recommande des images de base minimales (Alpine, distroless ou variantes slim officielles) avec un épinglage de version exact pour...

npx skills add https://github.com/github/awesome-copilot --skill multi-stage-dockerfile

Your goal is to help me create efficient multi-stage Dockerfiles that follow best practices, resulting in smaller, more secure container images.

Multi-Stage Structure

  • Use a builder stage for compilation, dependency installation, and other build-time operations
  • Use a separate runtime stage that only includes what's needed to run the application
  • Copy only the necessary artifacts from the builder stage to the runtime stage
  • Use meaningful stage names with the AS keyword (e.g., FROM node:18 AS builder)
  • Place stages in logical order: dependencies → build → test → runtime

Base Images

  • Start with official, minimal base images when possible
  • Specify exact version tags to ensure reproducible builds (e.g., python:3.11-slim not just python)
  • Consider distroless images for runtime stages where appropriate
  • Use Alpine-based images for smaller footprints when compatible with your application
  • Ensure the runtime image has the minimal necessary dependencies

Layer Optimization

  • Organize commands to maximize layer caching
  • Place commands that change frequently (like code changes) after commands that change less frequently (like dependency installation)
  • Use .dockerignore to prevent unnecessary files from being included in the build context
  • Combine related RUN commands with && to reduce layer count
  • Consider using COPY --chown to set permissions in one step

Security Practices

  • Avoid running containers as root - use USER instruction to specify a non-root user
  • Remove build tools and unnecessary packages from the final image
  • Scan the final image for vulnerabilities
  • Set restrictive file permissions
  • Use multi-stage builds to avoid including build secrets in the final image

Performance Considerations

  • Use build arguments for configuration that might change between environments
  • Leverage build cache efficiently by ordering layers from least to most frequently changing
  • Consider parallelization in build steps when possible
  • Set appropriate environment variables like NODE_ENV=production to optimize runtime behavior
  • Use appropriate healthchecks for the application type with the HEALTHCHECK instruction