Comment 27 for bug 1821696

Seems that the above method of making /etc/libvirt/secrets a docker volume alone means the container fails:

http://logs.openstack.org/53/650853/1/check/kolla-ansible-ubuntu-source-ceph/4051ac0/primary/logs/docker_logs/nova_libvirt.txt.gz

I think adding merge will avoid that issue though, since the delete is skipped in that case.