Comment 2 for bug 997700

It would be nice to have a generic mapping table that can be specified in the config. Since LDAP is fairly malleable and users can create their own schema there is a good chance that people want to use non-standard attributes for various fields with keystone. Also, having a generic mapping table would make it easier for people who are interested in using other ldap servers (such as Active Directory) as a backend.

From my (perhaps limited) experience, the defaults you want for a Unix style environment are: uid, cn, posixAccount

posixAccount requires cn and uid:

https://www.google.com/search?q=posixaccount+schema

However, it's possible that people want to use other attributes (again, AD as a prime example)