beginner~4h

Dockerfile Instructions & Multi-Stage Builds

A Dockerfile is a declarative, line-by-line recipe for building an image. Each instruction either creates a new layer (FROM, RUN, COPY, ADD) or sets image metadata that doesn't add a filesystem layer

Learning objectives

  • Explain what each of the core Dockerfile instructions actually does at build time versus at container-run time.
  • Explain precisely what problem multi-stage builds solve, and what happens to a discarded build stage.
  • Distinguish CMD from ENTRYPOINT, and predict how they combine when both are present.

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Dockerfile Instructions & Multi-Stage Builds

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