As a cloud administrator, you can manage projects, users, and roles. Projects are organizational units in the cloud to which you can assign users. Projects(tenants) are also known as accounts. Users can be members of one or more projects. Roles define the actions that users can perform.
Each OpenStack deployment must include at least one project, one user, and one role, linked together. As a cloud administrator, you can add, update, and delete projects and users, assign users to one or more projects, and change or remove these assignments. You can manage projects and users independently from each other.
You can also configure user authentication with the Keystone identity service to control access to services and endpoints. Keystone provides token-based authentication and can integrate with LDAP and Active Directory, so you can manage users and identities externally and synchronize the user data with Keystone.
Keystone v2 was deprecated in Red Hat OpenStack Platform 11 (Ocata). It was removed in Red Hat OpenStack Platform 13 (Queens), leaving only Keystone v3 available.