Re: networking service not starting with netlink-response-error errno:17

["Ludovic Courtès" <ludo@gnu.org>]

Hi Giovanni,

Giovanni Biscuolo <g@xelera.eu> skribis:

> after a reboot on a running remote host (it was running since several
> guix system generations ago... but with no reboots meanwhile) I get a
> failing networking service and consequently the ssh service (et al)
> refuses to start :-(
>
> Sorry I've no text to show you but a screenshot (see attachment below)
> because I'm connecting with a remote KVM console appliance.
>
> The networking service is failing with this message (manually copied
> here, please forgive mistakes):
>
>
> [...] 11:28 vmunix [...] shepherd [1]: Exception caught while starting
> networking: (no-such-device "swws-bridge")
>
>
> shepherd [1]: Exception caught while staring networking. (%exception
> #<&netlink-response-error errno: 17>)

17 = EEXIST, which is netlink’s way of saying that the device/route/link
it’s trying to add already exists.

The problem here is that static networking adds devices, routes, and
links (see ‘network-set-up/linux’ in the code).  If it fails in the
middle, then it may have added devices without adding routes, so you end
up with half-configured networking.  Ideally this would be
transactional.

When that happens, you need to check the logs and use the ‘ip’ command
to figure out which part failed exactly.  In your case, the root problem
seems to be that “swws-bridge” did not exist.

Then you can (1) manually fix it with ‘ip’, and (2) adjust your Guix
System config to fix the problems you found.

This is inconvenient at best.  I would be interested in hearing
suggestions on how to improve on this.

HTH,
Ludo’.