>The design of the language in Dockerfile is ad hoc in a bad way. It’s difficult to understand, for me, and easy to make mistakes.
Because that reads like a skill issue to me
The question is not if it's a skill issue or not, but if the complexity of the solution matches the complexity of the problem domain. And also: if there are easier and clearer ways to reach the same goals.
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
RUN <<END
set -eu
foo
bar
baz
END
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.
liw is Lars Wirzenius, so I assume we can rule that out.