Kubernetes node went to pieces. Apparmor prevented nginx from doing anything sensible, so the ingress didn't work. Easy fix when you know what's up, not so apparent when starting troubleshooting.

One app invoked tshark in a pod, apparmor denied it.

Those two were the visible ones. Apparmor now also blocks some unix signals that e.g. postgres uses in a few circumstances - leaving latent annoying bugs.

Pod shutdown hangs. Logs indicate 7 more apps affected by the signal "armor".

We're banning any new Ubuntu installs.