DCA Question #33: Real Exam Question with Answer & Explanation

Question

What is the purpose of multi-stage builds?

Options

• ABetter logical separation of Dockerfile instructions for better readability
• BOptimizing images by copying artifacts selectively from previous stages
• CBetter caching when building Docker images
• DFaster image builds by allowing parallel execution of Docker builds

Explanation

Multi-stage builds are primarily used to optimize Docker images by reducing their size and attack surface.

Common mistakes.

• A. While multi-stage builds can improve the logical organization of a Dockerfile, their main purpose is not just readability but concrete image optimization.
• C. Although caching is leveraged during multi-stage builds, it's a general Docker build feature; the primary purpose of multi-stage builds is not better caching, but image size reduction through artifact selection.
• D. Multi-stage builds execute stages sequentially; they do not inherently allow for parallel execution of Docker builds, which would typically require separate build processes.

Concept tested. Docker multi-stage builds for image optimization

Reference. https://docs.docker.com/build/building/multi-stage/

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