podman build doesn't support --load or --push

[dylex]

Bug description

When trying to build using podman with --push, you get an error unknown flag: --push. Since commit 07e97ee repo2docker tries to use podman buildx build --push but this isn't supported in podman. Reverting this commit allows podman to get a bit further (there are still other issues I'm trying to work out).

If podman is no longer supported, instead the documentation should be updated.

[dylex]

I just discovered https://github.com/manics/repo2podman. Is the intention that this is the only way podman is supported? I didn't see any reference to it in the docs.

[minrk]

I'll defer to @rgaiacs and @manics for clarifying the podman support situation.

As I understood it here, we don't generally support the podman cli in this repo if/where it deviates from the docker, that requires a plugin providing the ContainerEngine interface, which is what repo2podman provides, but do if/where podman is the engine backing the docker cli.

FWIW, my podman (5.8.2) does support --load, but not --push, so local repo2docker use does work, but not --push workflows (e.g. binderhub).

I don't think it would be difficult to fix that, if it's the only thing.

[rgaiacs]

Thanks @dylex for report the issue.

I believe that our tests do not cover the --push option as it introduces a external point of failure to the tests, for example, when the container registry used for the tests is down.

My understanding is that the team behind podman decided to follow a striker "Unix philosophy", i.e. "write programs that do one thing and do it well", and not include the --push option to build.

The repo2docker's option --push is defined in

repo2docker/repo2docker/__main__.py

Lines 202 to 207 in 5d82661

	argparser.add_argument(
	"--push",
	dest="push",
	action="store_true",
	help="Push docker image to repository",
	)

and used in

repo2docker/repo2docker/docker.py

Lines 167 to 168 in 5d82661

	if push:
	args.append("--push")

We can do a small refactor and run docker push / podman push after

repo2docker/repo2docker/docker.py

Line 209 in 5d82661

yield from execute_cmd(args, True)

[dylex]

Great, thanks, happy to help with PRs as well, just wanted to make sure that support was intended.