Butane config for automatic bootable container rebase

[cyl3x]

Describe the enhancement

Use of CoreOS disk/boot images

And more explicitly, it's expected that many if not most users would continue to use the official Fedora CoreOS "boot images" (e.g. ISO, AMI, qcow2, etc.). This proposal does not currently call for exposing a way for a user to create the boot image shell around their custom container, although that is an obvious potential next step.

Hence, a user wanting to use a custom base image would provide machines with an Ignition config that performs e.g. rpm-ostree rebase ostree-remote-image:quay.io/examplecorp/baseos:latest as a systemd unit. It is likely that we would provide this via Butane as well; for example:

variant: fcos
version: 1.5.0
ostree_container:
  image: quay.io/mycorp/myfcos:stable
  reboot: true

Resource: coreos/enhancements

Is this still being considered? I would love to see this feature

System details

No response

Additional information

No response

[navaati]

Do the dev team consider it possible to do the rebase in the initrd before switchroot, allowing it to happen without reboot ? Beside being more natural for the general case, this is crucial for the PXE/ISO boot usecase.

cf. #681 (comment)

[jlebon]

Do the dev team consider it possible to do the rebase in the initrd before switchroot, allowing it to happen without reboot ? Beside being more natural for the general case, this is crucial for the PXE/ISO boot usecase.

I think the more likely thing to happen is containers/bootc#76, which ideally also works in the live case.

And then one way to streamline this is to have a UX that isolates to a target that does bootc apply-live and then systemctl soft-reboot.

Streamlining it further so that the apply-live happens from the initrd (and avoid the soft reboot) is possible, but adds a lot of complexity so the benefit/cost ratio becomes murkier. If you need something more efficient, you likely would instead prefer to build your own custom disk images/PXE artifacts from the container image, which will be a supported operation.