优化 Docker 镜像涉及减少大小(更小、更快、更安全)和改进构建性能(通过缓存实现更快的构建)。技术包括最小基础镜像、多阶段构建、层优化、BuildKit 和精心设计 Dockerfile。
减少镜像大小
✓ MINIMAL base images:
- alpine (tiny, ~5MB) — but musl libc can cause compatibility issues for some apps
- slim variants (e.g. python:3.12-slim) — smaller than full, fewer compat issues
- DISTROLESS — only the app + runtime, NO shell/package manager (smallest, most secure)
- scratch — empty base (for static binaries, e.g. Go) → minimal image
✓ MULTI-STAGE builds — build with tools, ship only the artifact (huge size savings)
✓ Combine RUN layers + clean up IN the same layer:
RUN apt-get update && apt-get install -y x && rm -rf /var/lib/apt/lists/*
(cleanup in a SEPARATE layer doesn't shrink the image — the files are in the earlier layer)
✓ .dockerignore — keep junk out of the context/image
✓ Remove caches, temp files, dev dependencies in production images
