ENTRYPOINT / CMD transformation to exec form is not a no-op

[thiagowfx]

Consider this sample Dockerfile (abridged version of a real-world scenario):

ENTRYPOINT sleep infinity
CMD sleep infinity

Let's run dockerfmt (v0.3.7) in it:

% dockerfmt Dockerfile
ENTRYPOINT ["sleep", "infinity"]
CMD ["sleep", "infinity"]

At first glance, everything looks OK. The problem is that this transformation is not a no-op.

Looking at the docs:

• https://docs.docker.com/reference/dockerfile/#cmd
• https://docs.docker.com/reference/dockerfile/#shell-and-exec-form

If CMD is used to provide default arguments for the ENTRYPOINT instruction, both the CMD and ENTRYPOINT instructions should be specified in the exec form.

The difference is:

• the original code yields sleep infinity (correct!)
• the transformed code yields sleep infinity sleep infinity, which is an error (sleep: no such argument sleep)

One could argue that the original code is odd – the following would be conceptually simpler, and more idiomatic:

ENTRYPOINT ["sleep"]
CMD ["infinity"]

Or even:

ENTRYPOINT ["sleep", "infinity"]

Nonetheless, IMHO dockerfmt should not change the behavior in this case.

[reteps]

Closed by https://github.com/reteps/dockerfmt/releases/tag/v0.3.8