When you installed Openstack using packstack you might have faced openstack-keystone service issue. When try it to restart it fails with code-name keystone error.
I have done some research on it and found the solution.
The issue is with Openstack Keystone Service which we have configured using httpd deamon in answers.cfg file ( configuration file used to install Openstack using packstack)
Now openstack-keystone service will not start as http service is already in started mode and we haven’t created any relation between openstack-keystone and http service.
So to start openstack-keystone service we have to create symbolic link and point openstack-keystone service to http service.