[libvirt-users] Enabling capabilities in a container

I'm using libvirt_lxc to create and manage various containers. I need to enable certain capabilities in a container to support ctdb, and as a quick solution I decided to just enable them all. I *thought* this would do the trick, adding the following XML to my container config: <features> <capabilities policy='allow'> </capabilities> </features> After adding this to my container, I restarted it and tried to start the ctdb service again: # systemctl start ctdb.service Job for ctdb.service failed. See 'systemctl status ctdb.service' and 'journalctl -xn' for details. # systemctl status ctdb.service ctdb.service - CTDB Loaded: loaded (/usr/lib/systemd/system/ctdb.service; disabled) Active: failed (Result: exit-code) since Tue 2015-08-04 14:10:39 PDT; 8s ago Process: 4612 ExecStart=/usr/sbin/ctdbd_wrapper /run/ctdb/ctdbd.pid start (code=exited, status=1/FAILURE) Aug 04 14:10:37 pws-01 systemd[1]: Starting CTDB... Aug 04 14:10:37 pws-01 ctdbd[4629]: CTDB starting on node Aug 04 14:10:37 pws-01 ctdbd[4631]: Starting CTDBD (Version 2.5.4) as PID: 4631 Aug 04 14:10:37 pws-01 ctdbd[4631]: Created PID file /run/ctdb/ctdbd.pid Aug 04 14:10:37 pws-01 ctdbd[4631]: Unable to set scheduler to SCHED_FIFO (Operation not permitted) Aug 04 14:10:37 pws-01 ctdbd[4631]: CTDB daemon shutting down Aug 04 14:10:39 pws-01 ctdbd_wrapper[4612]: CTDB exited during initialisation - check logs. Aug 04 14:10:39 pws-01 systemd[1]: ctdb.service: control process exited, code=exited status=1 Aug 04 14:10:39 pws-01 systemd[1]: Failed to start CTDB. Aug 04 14:10:39 pws-01 systemd[1]: Unit ctdb.service entered failed state. This implies that the container still doesn't have access to the capabilities it needs to use. I believe this error in fact is caused by the container not having the sys_nice capability. So I tried to allow this specific capability using: <features> <capabilities policy='default'> <sys_nice state='on'/> </capabilities> </features> This did not work either. So, what *is* the correct way to add capabilities to a container?