Keystone is an OpenStack project that provides Identity as a service to OpenStack services and components. Keystone is responsible for authenticating users and services, and authorizing access to OpenStack components.
Keystone also provides a service catalog that users and other services can query to discover the services OpenStack provides. For each service, Keystone Catalog returns an endpoint that is a network-accessible URL from where users and services can access a certain service.
Keystone, by default, runs under a built-in Eventlet Python service, but it can be configured to run under the Apache httpd service that provides better security and scalability.
Keystone services are as follows: