Comment 4 for bug 1669729

I think this is something that we would be happy to have, but also something that is fairly low priority currently.

There is also a bit to understand the implications and what should happen if one of these fields change. (what hooks should run on a charm if the AZ changes?) Will the charms themselves support/notice the value changing. (IIRC, things like ceph make use of it when setting up ceph for the first time, but don't support that value changing after the fact, eg reconfiguring the mapping.)