Switch /etc to use confext in mutable mode #3555
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From 7f0d7d0eb24afe14cd62bfa78cb9e139b9f824d1 Signed-off-by: Kai Lueke <kailuke@microsoft.com>
From d45a090cf70ae75de9e22b54016b049a90f7abc8 Signed-off-by: Kai Lueke <kailuke@microsoft.com>
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For A/B-updated /etc contents we used a custom overlay mount that provides the default files through a lowerdir loaded from /usr. Since then we upstreamed mutable systemd-confext support and now we can switch to it. This pulls in flatcar/init#138 and flatcar/bootengine#115 together with backported systemd patches that have opened or merged upstream PRs to fix --root= issues and add a refresh skip check to prevent boot disruptions due to the multiple daemon reloads and - more important - the missing atomic remount that would mean /etc is gone for a few milliseconds during boot. The skip logic works best with verity hashes and thus the default confext must be a verity extension image. User-provided confext don't work well yet unless they use verity due to the missing atomic remount and reliance on the skipping logic. We also need to look into stacking order and other mutabiliy settings. Signed-off-by: Kai Lueke <kailuke@microsoft.com>
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For A/B-updated /etc contents we used a custom overlay mount that
provides the default files through a lowerdir loaded from /usr. Since
then we upstreamed mutable systemd-confext support and now we can switch
to it.
This pulls in flatcar/init#138 and
flatcar/bootengine#115 together with backported
systemd patches that have opened or merged upstream PRs to fix --root=
issues and add a refresh skip check to prevent boot disruptions due to
the multiple daemon reloads and - more important - the missing atomic
remount that would mean /etc is gone for a few milliseconds during boot.
The skip logic works best with verity hashes and thus the default
confext must be a verity extension image.
User-provided confext don't work well yet unless they use verity due to
the missing atomic remount and reliance on the skipping logic. We also
need to look into stacking order and other mutabiliy settings.
This includes a systemd update to 258.2 to have a smaller diff for the backports.
How to use
Update git refs before merging.
Testing done
We should also add a mantle kola test for "Skipping extension refresh because no change was found" for sysext and confext because we never want to have a refresh during boot on an unmodified Flatcar image.
TODO: CI and Jenkins.
changelog/directory (user-facing change, bug fix, security fix, update)/bootand/usrsize, packages, list files for any missing binaries, kernel modules, config files, kernel modules, etc.