Having openstack client installed ( yum install python-openstackclient ) tested on Mitaka :-
Fisrt created

[root@ip-192-169-142-127 ~(keystone_glance)]# cat keystonerc_glance
unset OS_SERVICE_TOKEN
export OS_USERNAME=glance
export OS_PASSWORD=f6a9398960534797
export OS_AUTH_URL=http://192.169.142.127:5000/v2.0
export PS1='[\u@\h \W(keystone_glance)]\$ '
export OS_TENANT_NAME=services
export OS_REGION_NAME=RegionOne

Then source credentials

[root@ip-192-169-142-127 ~(keystone_glance)]# openstack  user role list glance
+----------------------------------+---------------+----------+--------+
| ID                               | Name          | Project  | User   |
+----------------------------------+---------------+----------+--------+
| ae6999aeb9ec46f89234edc7ffeb53ed | admin         | services | glance |
| 99e21265b7ad4486b7a991ff0bcd2110 | ResellerAdmin | services | glance |
+----------------------------------+---------------+----------+--------+

I just added second role to glance to be able have swift as back end.
Another sample "john" has role "admin" in project "ostenant" , james doesn't
Looks like I have source john's credentials to get info about james's roles

[root@ip-192-169-142-127 ~(keystone_john)]# openstack  user role list john
+----------------------------------+-------+----------+------+
| ID                               | Name  | Project  | User |
+----------------------------------+-------+----------+------+
| ae6999aeb9ec46f89234edc7ffeb53ed | admin | ostenant | john |
+----------------------------------+-------+----------+------+
[root@ip-192-169-142-127 ~(keystone_john)]# openstack  user role list james
+----------------------------------+---------------+----------+-------+
| ID                               | Name          | Project  | User  |
+----------------------------------+---------------+----------+-------+
| 35a908c26ce34a63b4c48109e76eb89b | SwiftOperator | ostenant | james |
+----------------------------------+---------------+----------+-------+