Add --parents option for COPY in Dockerfiles

[uckelman]

Description

Docker added a --parents option to the Dockerfile COPY command last year:

moby/moby#35639
moby/buildkit#3001
https://docs.docker.com/reference/dockerfile/#copy---parents

buildah doesn't know how to handle COPY --parents so errors out on Dockerfiles which use it.

I'm seeing increasing use of --parents in Dockerfiles I have to deal with, which is making it hard to use podman/buildah instead of Docker. --parents is also a genuinely useful option on its own, so would be nice to have not just for compatibility.

It's quite useful to be able to do things like

COPY --parents src/**/pyproject.toml src/**/poetry.lock /app/

and maintain the directory structure in the destination without having to list out every single file.

[TomSweeneyRedHat]

I believe @mheon is either working on this or looking into this. Matt?

[mheon]

Yep, hoping to get to this over the next few weeks

[github-actions]

A friendly reminder that this issue had no activity for 30 days.

[cyqsimon]

This is so badly needed with Java projects that involve multiple pom.xml files. Any progress on this?