UKI addon - how?

[rlees85]

I can see that bootc supports UKI addons when using composefs. Very useful for machine-specific kernel arguments!

I just cannot figure out how it works.

I've read all the RedHat docs around UKI addons, I've even tried reading the source code of bootc and composefs-rs and I just cannot figure it out. Where exactly do the addon EFIs have to be placed at install time in order for bootc to pick them up?

If I don't bake them into my container bootc silently ignores them and if I do it complains the composefs digest is missing (which is expected, its just an addon). Ive tried the ${UKI_NAME}.efi.extra.d/my-addon.addon.efi structure too bit it still complains.

Any help on the correct way to do this? Much appreciated

[Johan-Liebert1]

${UKI_NAME}.efi.extra.d/my-addon.addon.efi, is the correct place to put any addon. You can then pass --uki-addon my-addon to bootc install ... See https://github.com/bootc-dev/bootc/blob/main/docs/src/man/bootc-install-to-disk.8.md?plain=1#L189

We intentionally do not install all addons present in the image. The support for upgrading addons is not there yet. Also, afair, currently addons are not installed globally, i.e. they're installed per deployment. Related #1780

[rlees85]

Ah perfect. bootc install is picking them up now.

Weirdly after reading that discussion, as long as the addons are retained during bootc update (which has no --uki-addon parameter afaik) the current implementation works perfectly for my use case (per machine GPU flags) and having them baked into the image as selectable options is nice.

Having machine specific filesystem flags working in this way feels like it would work nicely too.

The addons not updating do the latest in-image versions at bootc update time would be a shame but I'd imagine them changing would be rare anyway.