Comment 0 for bug 1709536

It looks like snapd in ubuntu-core (2.26.14 here) has been modified to use a negative Nice value in systemd. Systemd seems to treat a failure to apply the requested Nice value as critical to unit startup.

Unprivileged LXD containers do not allow the use of negative nice values as those are restricted to the real root user. I believe the optimal fix would be for systemd to ignore permission errors when attempting to setup such custom nice values in containers but if that can't be resolved quickly, then it means that snapd will now fail to start inside containers.

Aug 09 05:54:37 core systemd[1]: snapd.service: Main process exited, code=exited, status=201/NICE
Aug 09 05:54:37 core systemd[1]: snapd.service: Unit entered failed state.
Aug 09 05:54:37 core systemd[1]: snapd.service: Failed with result 'exit-code'.

I have confirmed that setting up a unit override by hand which sets Nice=0 does resolve the problem, confirming that the negative Nice value is the problem (snapd.service has Nice=-5 here).