In RHOSP18 next-gen, when the libvirt_* containers of Nova start, they re-set permissions on all that is running inside /run/libvirt. Ceilometer needs access to /run/libvirt/virtqemud-sock-ro to get libvirt metrics.

When a libvirt_* container restarts, Ceilometer starts failing with:

libvirt: XML-RPC error : Failed to connect socket to '/var/run/libvirt/virtqemud-sock-ro': Permission denied

because the permissions have changed in the disk. This is fixable with a reconnection to the socket.

Ceilometer must detect when this happens, control the error and then it can do two things:

• Attempt to reconnect
• Fail and exit

In the second option, the container that is running Ceilometer will automatically restart, triggering a reconnection.