[homebrewer]

Dockerfile is one of the worst parts of docker — it's a primitive shell-like DSL that didn't have to exist and that feels like it was designed by a person with a couple of hours of experience in writing shell scripts.

Instead of providing a set of separate tools to be glued together with a proper shell or a full programming language, they designed this nonsense that can't even do 1/10th of what busybox is able to do, and have been in the business of adding the missing pieces (like `COPY --chmod`) for the past 10+ years.

It has taken them about a decade to add HEREDOC support, for example. Most dockerfiles still use

  RUN foo && \
      bar && \
      baz

instead of

  RUN <<END
    set -eu
    foo
    bar
    baz
  END

I avoid dockerfiles and prefer using buildah for building containers. Since they're all using the same specification, it doesn't matter what runtime is then used to run them: it can be docker, podman, k8s, whatever.

Here's the official example of building a lighttpd container:

https://github.com/containers/buildah/blob/92015b7f4301d7eb8...

You can eschew bash and call these commands however you want — from a python script, or Go, or even assembly.