13 · Environments & Packaging
Dockerfile
Recipe for a container image
A text file of build steps that produce a Docker image—base image, copy files, install deps, set the start command.
Concrete example
A Dockerfile might start `FROM node:22`, copy the app, run `npm ci`, and `CMD ["node","server.js"]`.
Why it matters
How agents package an app so it runs the same in CI and production.