This charm provides Keystone, the Openstack identity service. It's target platform is Ubuntu Precise + Openstack Essex. This has not been tested using Oneiric + Diablo.

It provides three interfaces.

- identity-service:  Openstack API endpoints request an entry in the 
  Keystone service catalog + endpoint template catalog.  When a relation
  is established, Keystone receives: service name, region, public_url,
  admin_url and internal_url.  It first checks that the requested service
  is listed as a supported service.  This list should stay updated to
  support current Openstack core services.  If the services is supported,
  a entry in the service catalog is created, an endpoint template is
  created and a admin token is generated.   The other end of the relation
  recieves the token as well as info on which ports Keystone is listening.

- keystone-service:  This is currently only used by Horizon/dashboard
  as its interaction with Keystone is different from other Openstack API
  servicies.  That is, Horizon requests a Keystone role and token exists.
  During a relation, Horizon requests its configured default role and
  Keystone responds with a token and the auth + admin ports on which
  Keystone is listening.

- identity-admin:  Charms use this relation to obtain the credentials
  for the admin user.  This is intended for charms that automatically
  provision users, tenants, etc. or that otherwise automate using the
  Openstack cluster deployment.

Keystone requires a database. By default, a local sqlite database is used. The charm supports relations to a shared-db via mysql-shared interface. When a new data store is configured, the charm ensures the minimum administrator credentials exist (as configured via charm configuration)

VIP is only required if you plan on multi-unit clusterming. The VIP becomes a highly-available API endpoint.