gitlab and gitolite can be integrated with Active Directory (or another LDAP server), but how it works is a bit roundabout.

• User logs in to gitlab web interface
• gitlab checks user’s credentials against Active Directory (via ominauth plugin) and allows log in
• User uploads SSH key via gitlab web interface
• gitlab writes key to gitolite keys dir?
• User attempts to access repo via SSH (e.g. git clone git@host:repo.git)
• SSH key is sent
• gitolite checks keys dir and finds key
• gitolite checks repository permissions and decides to allow the operation
  • This could be because user is a member of an AD group which has been assigned perms in gitolite.conf
  • Script to pull group info from AD
• repo is cloned

Simples!