Bug#944860: udevadm trigger fails in chroot

[Michael Biebl]

Control: retitle -1 udevadm trigger fails in containers with ro /sys

Am 17.11.19 um 02:43 schrieb Michael Biebl:
> Am 17.11.19 um 01:57 schrieb Jonah Brüchert:
>> After slightly looking into the debos source code it seems also possible
>> that it uses a systemd-spawn container in some cases
>> (https://github.com/go-debos/debos/blob/2764eed783b1b0ffb5d09f796338f09a4e2594b6/commands.go#L15)
> 
> Can you please verify, what exactly you are using:
> A container (systemd-nspawn,...), chroot or something else.
> If it's a chroot, it would be good to know how the chroot is setup,
> (e.g. which file systems are mounted into the chroot etc).

Assuming you do actually use systemd-nspawn, I think I found the commit
which changed the behaviour of udevadm:

> commit 97afc0351a96e0daa83964df33937967c75c644f (refs/bisect/bad)
> Author: Zbigniew J<C4><99>drzejewski-Szmek <zbyszek at in.waw.pl>
> Date:   Wed Jun 5 09:54:54 2019 +0200
> 
>     udevadm trigger: log errors and return first failure
>     
>     When udevadm trigger is called, the list of devices to trigger is always
>     generated through enumeration, and devices can come and go, so we should not
>     treat -ENOENT as a failure. But other types of failure should be logged.
>     It seems they were logged until baa30fbc2c04b23209d0b8fb3c86cd15ef9ea81a.
>     
>     Also, return the first error. (I'm not sure if there are other failure modes
>     which we want to ignore. If they are, they'll need to be whitelisted like
>     -ENOENT.).

https://github.com/systemd/systemd/commit/97afc0351a96e0daa83964df33937967c75c644f

Whereas with v242 it would log only with debug level priority and return
0, with v243 it now logs with error level priority and returns 1.

I assume this change was deliberate.

This is unfortunate as we have quite a few packages calling "udevadm
trigger" in postinst [1].

So, I think "udevadm trigger" actually behaves properly in a chroot as
it becomes a nop there. In a container with a ro /sys it now fails.
I just checked and LXC containers are affected as well.

Retitling the bug report accordingly.



[1] https://codesearch.debian.net/search?q=udevadm+trigger&literal=0
-- 
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