[Kolla] why is Ceph package installed in OVN container?

Hi, Regarding to Kolla OVN Ussuri container, for example [1], image layer #28. Why is centos-release-ceph-nautilus installed in OVN container? [1] https://hub.docker.com/layers/kolla/centos-binary-ovn-nb-db-server/ussuri/im... Thanks! Tony