Re: Automatic creation of last-known-good boot configuration
Jens Schmidt (12024-07-10):
> On Debian testing I've been bitten by the systemd upgrade and the
> systemd package split recently, rendering my dracut-LUKS-based
> system unbootable. I know that my warranty is void since I'm on
> testing, but both these issues would have been much easier to cope
> with if there had been some good backup of my initramfs and kernel
> below /boot.
>
> So I thought that there might be some automatism like this:
>
> If the currently used kernel and initramfs have been in use
> already N times and if the boot time has been lower then M
> minutes each time (and if some other conditions are fulfilled),
> then consider that kernel and initramfs good and save them away
> where they will not be overwritten by regular kernel/initramfs
> maintenance.
>
> Scripting something like that shouldn't be too hard, but I wonder
> if there already is a package implementing that? A cursory search
> hasn't brought up anything. There is package dracut-config-rescue,
> but that only configures a variable that does not seem to be used
> by dracut itself.
I will say: this is probably not possible with Debian, since an apt-get
(dist-)uupgrade replaces distributed files, and initrds are rebuilt,
etc.
You can consider using a LVM snapshot, but you can only make one
reliably when the system is read-only. You can consider using a
filesystem snapshot, but filesystems that support snapshots have their
own set of problems.
On the other hand, I can say it is a feature of NixOS, I saw it last
week when somebody asked me “I made a mistake, our VM doesn't boot
anymore, can I access the GRUB console?” and they just rebooted on the
previous configuration. But NixOS is not Debian, it is barely Unix as
far as I can see.
Regards,
--
Nicolas George
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