Port to Ignition v3

[pothos]

• dracut/30ignition/ignition-setup.sh: migrate to Ignition v3
  In Ignition v3 we don't have a "default" config anymore and there can
  now be multiple "base" configurations but they have to be in a
  subfolder.
  Skip copying the "default" config, which should be repaced by a new OEM
  systemd service that checks whether Ignition found a config or not.
  Use the new "base.d" subfolder as target for the OEM "base" config.
• dracut/99setup-root: Fix failed setup of wants dependency
  The build log contained this error message:
  ln: failed to create symbolic link '/var/tmp/portage/sys-kernel/coreos-kernel-5.15.24/temp/dracut.Ddrb5k/initramfs//usr/lib/systemd/system/initrd.target.wants/initrd-setup-root.service': No such file or directory
  Make sure the directory exists to be able to set up the link.
• Port to Ignition v3
  The dracut/30ignition files had to be updated to match the folder
  dracut/30ignition found in the ignition repo but with some adaptions
  because Flatcar allows to overwrite the root filesystem and has a
  different initramfs service setup.
  For Ignition v3 we had to provide an implementation for is-live-image
  and ignition-kargs-helper. The kargs helper does not handle all cases
  due to the complexity of evaluation grub.cfg.

How to use

Goes with the Ignition v3 update

Clevis is not yet supported. We need docs for the kargs support.

Testing done

With this v3 config we have can control that the kernel arguments in /usr/share/oem/grub.cfg contains only the entry that should exist but no the other if it was present.

{
  "ignition": {
    "version": "3.3.0"
  },
  "storage": {
    "files": [
      {
        "path": "/works",
        "contents": {
          "source": "data:,helloworld%0A",
          "verification": {}
        },
        "mode": 420
      }
    ]
  },
  "kernelArguments": {
    "shouldExist": ["ishouldexist"],
    "shouldNotExist": ["ishouldnotexist"]
  }
}

• Changelog entries added in the respective changelog/ directory (user-facing change, bug fix, security fix, update)
  ↑ will do in coreos-overlay

[tormath1]

well it looks good to me, and the CI is passing. Just have one question regarding the Documentation= parameter in unit files, they target CoreOS' github not sure if we should keep them or use Flatcar's URL.

[pothos]

I think it's ok to use the upstream URL (not even sure if someone sees these entries). It also reduces the noise when comparing the files to upstream.

[tormath1]

It also reduces the noise when comparing the files to upstream.

Yeah, I agree too - so let's merge this. 🎉