cli: Add a new bootc image subcommand

[cgwalters]

We have a basic bootc image list but more interesting is
bootc image push which defaults to copying the booted
image into the container storage.

Signed-off-by: Colin Walters walters@verbum.org

[cgwalters]

$ bootc image list
docker://<your image here>
$ bootc image push
...
$ podman run --rm -ti localhost/bootc bash
# Now we're in the booted host as a container

This is aimed to close the biggest gap in https://containers.github.io/bootc/booting-local-builds.html - because then we can easily add something like bootc switch --local which would default to pulling from localhost/bootc in the container storage, closing the loop.

This builds on ostreedev/ostree-rs-ext#642 which has notes about its inefficiencies.

[cgwalters]

OK yes, this PR also hit the install flake (I added it to #579 )

Creating root filesystem (xfs) on device /dev/loop0p1 (size=1M)
> mkfs.xfs -m uuid=790e772b-c617-47dc-af23-04ca799c8aad -L root /dev/loop0p1
size 256 of data subvolume is too small, minimum 4096 blocks

With the new size printing we can clearly see that the partition size is just 1M. I'm going to add some more logging to see if I can figure out more here.

[cgwalters]

OK this one now has a test based on the framework added in #625

[vrothberg]

I´d love to see docs (no blocker) and like to bikeshed a bit on the naming of push. It feels more like a write-to-storage or something down these lines.

[cgwalters]

I´d love to see docs (no blocker)

I've updated that, though note that right now this is hidden from the CLI as an experimental feature so we can use it in our own CI, and stabilize things later.

and like to bikeshed a bit on the naming of push. It feels more like a write-to-storage or something down these lines.

The default is indeed like copy-to-storage or so, but the functionality is more general than that in that we support e.g. bootc image push --target quay.io/exampleos/someimage:latest.

That said...it would actually simplify things perhaps if we only supported bootc image copy-to-storage <tag> because one can then of course directly use podman for them.

There's also the longer term bikeshed topic of (assuming we made it actually efficient and not a physical copy) if the default should actually be to keep the bootc image visible in containers-storage or so.

[vrothberg]

That said...it would actually simplify things perhaps if we only supported bootc image copy-to-storage <tag> because one can then of course directly use podman for them.

Agreed, that sounds like a good idea 👍

[cgwalters]

OK it's now called bootc image copy-to-storage and I dropped the --transport option, so it only supports containers-storage:.

[vrothberg]

LGTM thank you!

[cgwalters]

I dropped the conflicting logging change to kargs from here for now, will split it out separately.