Articles/General

a Dockerfile Explained

What a Dockerfile does, with an example.

Published November 9, 2026

a Dockerfile is a text file containing step-by-step instructions Docker uses to build an image.

Key points

  • Part of the standard Docker CLI used for building, running, and managing containers

Example

FROM node:20
COPY . .
RUN npm install
CMD ["node", "index.js"]
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