**Use case**
In some organisations are using AD with hierarchical structure (nested organisation unit) and DN follow this structure. As result we can not  use permanent build_dn for users with different OU.

**Describe the solution you'd like**
Solution can be look like:
1) bind as service account
2) set dn for user_name by some filter string to user_dn
3) bind as user_dn with password
3) use user_dn with filter for group/roles fetching

This approach is implemented in Metabase.

throwAddressNotAllowed(address);
        if (!areLDAPCredentialsValidNoLock(*user, credentials, external_authenticators, external_roles))
            throwInvalidCredentials();
        assignRolesNoLock(*user, external_roles);
        return memory_storage.insert(user);
    }
}
UUID LDAPAccessStorage::getIDOfLoggedUserImpl(const String & user_name) const
{
    std::scoped_lock lock(mutex);
    auto id = memory_storage.find<User>(user_name);
    if (id)
    {
        return *id;
    }
    else
    {
        
        auto user = std::make_shared<User>();
        user->setName(user_name);
        user->authentication = Authentication(Authentication::Type::LDAP);
        user->authentication.setLDAPServerName(ldap_server_name);
        LDAPClient::SearchResultsList external_roles;
        
        assignRolesNoLock(*user, external_roles);
        return memory_storage.insert(user);
    }
}
}