#build

Every Dockerfile instruction you need day to day, what it does, and the difference between the commonly confused pairs (CMD vs ENTRYPOINT, COPY vs ADD, ARG vs ENV).

Build in one stage with the full toolchain, then copy only the finished artifact into a small runtime image. Typical result: images 5-10x smaller with no compilers or source code inside.

Builds an image from a Dockerfile — each instruction becomes a cached layer, so unchanged steps stay fast on rebuild.

"exec format error" or "no matching manifest for linux/arm64": the image was built for a different CPU architecture than the machine running it (amd64 vs arm64, e.g. Apple Silicon or AWS Graviton).