[ceph-users] RGW: is it possible to restrict a user access to a realm?

Hi, We have several RGW realms hosted in the same Ceph cluster. Looking at how to restrict access to one realm to some users (among all existing ones), I don't find the information. Looking at user/realm/zonegroup/zone parameters, I don't see anything that would allow this. I saw in https://docs.ceph.com/en/latest/radosgw/account/#radosgw-account a few words about tenant isolation but it is not clear for me if it is the same thing and  how you achieve it. Thanks in advance for any hint! Best regards, Michel