Dockerfile

Write a Dockerfile simply: FROM node, COPY ., CMD run. It works, and for local tests this is often enough. But when such an image reaches CI/CD or, God forbid, production, problems begin: builds take forever, the image weighs gigabytes, and the security team grabs their heads.

The difference between “it works” and “it works correctly” is huge. Let’s go through four levels of optimization that separate a hobbyist hack from a reliable engineering solution.