This document discusses Sungard Availability Services' implementation of multi-domain support and single sign-on in OpenStack. It describes the need for these features to support their managed cloud platform being used by multiple tenants. The key steps taken include updating Horizon and the authentication system to handle domain-scoped tokens and passing the domain from Keystone to Horizon after authentication. Policy files were also updated to restrict administrative access by domain. Issues remaining include API authentication and managing multiple sessions.