Lesson 02 · 13 min
Dockerfile: layers, cache and instructions
How Docker builds an image, why the order of lines decides build speed, and which instruction to use when.
13 minLesson 2 of 5Practice includedAsk AI on any point
A Dockerfile is the recipe for an image. Every instruction that changes files (RUN, COPY, ADD) creates a new layer. Layers stack on top of each other, and the image is that stack. Instructions like ENV, EXPOSE, CMD only change metadata.
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