Dockerfile Fundamentals
Write a correct, efficient Dockerfile from scratch and build/run a real image — covering FROM, RUN, COPY, WORKDIR, ENV, EXPOSE, CMD vs ENTRYPOINT, and HEALTHCHECK.
Prerequisites: Docker Engine installed and running (verify with docker --version); basic command-line comfort; a small app (Node.js or Python "hello world" works) to containerize.
Targeted versions: Docker Engine 29.x / Dockerfile syntax=docker/dockerfile:1 (verified against docs.docker.com, mid-2026).
In this project you'll take a plain script or small app and turn it into a portable container image using nothing but a text file called a Dockerfile. By the end you'll understand what each instruction actually does at build time versus run time, why instruction order affects build speed, and how to run the image you produce as a container with a published port.
Dockerfiles are read top to bottom. Docker runs each instruction in order and caches the result of each one as a layer, which is why the order you write instructions in has a real, measurable effect on how fast repeat builds are.
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