Add documentation on the usage of keystone's scope & roles

As Tempest support the keystone's scope and new default roles
like reader, this commit document that how those can be
requested and used in Tempest or its plugins tests.

Change-Id: Iebacbeda231f82d6d16dbdcde635f19ae862181f
diff --git a/doc/source/configuration.rst b/doc/source/configuration.rst
index c43e420..c790c5f 100644
--- a/doc/source/configuration.rst
+++ b/doc/source/configuration.rst
@@ -153,6 +153,11 @@
 
 Pre-Provisioned Credentials are also known as accounts.yaml or accounts file.
 
+Keystone Scopes & Roles Support in Tempest
+""""""""""""""""""""""""""""""""""""""""""
+For details on scope and roles support in Tempest,
+please refer to :doc:`this document <keystone_scopes_and_roles_support>`
+
 Compute
 -------
 
diff --git a/doc/source/index.rst b/doc/source/index.rst
index 66e68ea..2f29cf2 100644
--- a/doc/source/index.rst
+++ b/doc/source/index.rst
@@ -105,6 +105,14 @@
 
    tempest_and_plugins_compatible_version_policy
 
+Keystone Scopes & Roles Support in Tempest
+------------------------------------------
+
+.. toctree::
+   :maxdepth: 2
+
+   keystone_scopes_and_roles_support
+
 Stable Branch Support Policy
 ----------------------------
 
diff --git a/doc/source/keystone_scopes_and_roles_support.rst b/doc/source/keystone_scopes_and_roles_support.rst
new file mode 100644
index 0000000..f446f8c
--- /dev/null
+++ b/doc/source/keystone_scopes_and_roles_support.rst
@@ -0,0 +1,286 @@
+Keystone Scopes & Roles Support in Tempest
+==========================================
+
+OpenStack Keystone supports different scopes in token, refer to the
+`Keystone doc <https://docs.openstack.org/keystone/latest/admin/tokens-overview.html#authorization-scopes>`_.
+Along with the scopes, keystone supports default roles, one of which
+is a reader role, for details refer to
+`this keystone document <https://docs.openstack.org/keystone/latest/admin/service-api-protection.html>`_.
+
+Tempest supports those scopes and roles credentials that can be used
+to test APIs under different scope and roles.
+
+Dynamic Credentials
+-------------------
+
+Dynamic credential supports all the below set of personas and allows
+you to generate credentials tailored to a specific persona that you
+can use in your test.
+
+Domain scoped personas:
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+  #. Domain Admin: This is supported and can be requested and used from
+     the test as below:
+
+     .. code-block:: python
+
+         class TestDummy(base.DummyBaseTest):
+
+             credentials = ['domain_admin']
+
+             @classmethod
+             def setup_clients(cls):
+                 super(TestDummy, cls).setup_clients()
+                 cls.az_d_admin_client = (
+                     cls.os_domain_admin.availability_zone_client)
+
+  #. Domain Member: This is supported and can be requested and used from
+     the test as below:
+
+     .. code-block:: python
+
+         class TestDummy(base.DummyBaseTest):
+
+             credentials = ['domain_member']
+
+             @classmethod
+             def setup_clients(cls):
+                 super(TestDummy, cls).setup_clients()
+                 cls.az_d_member_client = (
+                     cls.os_domain_member.availability_zone_client)
+
+  #. Domain Reader: This is supported and can be requested and used from
+     the test as below:
+
+     .. code-block:: python
+
+         class TestDummy(base.DummyBaseTest):
+
+             credentials = ['domain_reader']
+
+             @classmethod
+             def setup_clients(cls):
+                 super(TestDummy, cls).setup_clients()
+                 cls.az_d_reader_client = (
+                     cls.os_domain_reader.availability_zone_client)
+
+  #. Domain other roles: This is supported and can be requested and used from
+     the test as below:
+
+     You need to use the ``domain`` as the prefix in credentials type, and
+     based on that, Tempest will create test users under 'domain' scope.
+
+     .. code-block:: python
+
+         class TestDummy(base.DummyBaseTest):
+
+             credentials = [['domain_my_role1', 'my_own_role1', 'admin']
+                            ['domain_my_role2', 'my_own_role2']]
+
+             @classmethod
+             def setup_clients(cls):
+                 super(TestDummy, cls).setup_clients()
+                 cls.az_d_role1_client = (
+                     cls.os_domain_my_role1.availability_zone_client)
+                 cls.az_d_role2_client = (
+                     cls.os_domain_my_role2.availability_zone_client)
+
+System scoped personas:
+^^^^^^^^^^^^^^^^^^^^^^^
+
+  #. System Admin: This is supported and can be requested and used from the
+     test as below:
+
+     .. code-block:: python
+
+         class TestDummy(base.DummyBaseTest):
+
+             credentials = ['system_admin']
+
+             @classmethod
+             def setup_clients(cls):
+                 super(TestDummy, cls).setup_clients()
+                 cls.az_s_admin_client = (
+                     cls.os_system_admin.availability_zone_client)
+
+  #. System Member: This is supported and can be requested and used from the
+     test as below:
+
+     .. code-block:: python
+
+         class TestDummy(base.DummyBaseTest):
+
+             credentials = ['system_member']
+
+             @classmethod
+             def setup_clients(cls):
+                 super(TestDummy, cls).setup_clients()
+                 cls.az_s_member_client = (
+                     cls.os_system_member.availability_zone_client)
+
+  #. System Reader: This is supported and can be requested and used from
+     the test as below:
+
+     .. code-block:: python
+
+         class TestDummy(base.DummyBaseTest):
+
+             credentials = ['system_reader']
+
+             @classmethod
+             def setup_clients(cls):
+                 super(TestDummy, cls).setup_clients()
+                 cls.az_s_reader_client = (
+                     cls.os_system_reader.availability_zone_client)
+
+  #. System other roles: This is supported and can be requested and used from
+     the test as below:
+
+     You need to use the ``system`` as the prefix in credentials type, and
+     based on that, Tempest will create test users under 'project' scope.
+
+     .. code-block:: python
+
+         class TestDummy(base.DummyBaseTest):
+
+             credentials = [['system_my_role1', 'my_own_role1', 'admin']
+                            ['system_my_role2', 'my_own_role2']]
+
+             @classmethod
+             def setup_clients(cls):
+                 super(TestDummy, cls).setup_clients()
+                 cls.az_s_role1_client = (
+                     cls.os_system_my_role1.availability_zone_client)
+                 cls.az_s_role2_client = (
+                     cls.os_system_my_role2.availability_zone_client)
+
+Project scoped personas:
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+  #. Project Admin: This is supported and can be requested and used from
+     the test as below:
+
+     .. code-block:: python
+
+         class TestDummy(base.DummyBaseTest):
+
+             credentials = ['project_admin']
+
+             @classmethod
+             def setup_clients(cls):
+                 super(TestDummy, cls).setup_clients()
+                 cls.az_p_admin_client = (
+                     cls.os_project_admin.availability_zone_client)
+
+  #. Project Member: This is supported and can be requested and used from
+     the test as below:
+
+     .. code-block:: python
+
+         class TestDummy(base.DummyBaseTest):
+
+             credentials = ['project_member']
+
+             @classmethod
+             def setup_clients(cls):
+                 super(TestDummy, cls).setup_clients()
+                 cls.az_p_member_client = (
+                     cls.os_project_member.availability_zone_client)
+
+  #. Project Reader: This is supported and can be requested and used from
+     the test as below:
+
+     .. code-block:: python
+
+         class TestDummy(base.DummyBaseTest):
+
+             credentials = ['project_reader']
+
+             @classmethod
+             def setup_clients(cls):
+                 super(TestDummy, cls).setup_clients()
+                 cls.az_p_reader_client = (
+                     cls.os_project_reader.availability_zone_client)
+
+  #. Project alternate Admin: This is supported and can be requested and used from
+     the test as below:
+
+     .. code-block:: python
+
+         class TestDummy(base.DummyBaseTest):
+
+             credentials = ['project_alt_admin']
+
+             @classmethod
+             def setup_clients(cls):
+                 super(TestDummy, cls).setup_clients()
+                 cls.az_p_alt_admin_client = (
+                     cls.os_project_alt_admin.availability_zone_client)
+
+  #. Project alternate Member: This is supported and can be requested and used from
+     the test as below:
+
+     .. code-block:: python
+
+         class TestDummy(base.DummyBaseTest):
+
+             credentials = ['project_alt_member']
+
+             @classmethod
+             def setup_clients(cls):
+                 super(TestDummy, cls).setup_clients()
+                 cls.az_p_alt_member_client = (
+                     cls.os_project_alt_member.availability_zone_client)
+
+  #. Project alternate Reader: This is supported and can be requested and used from
+     the test as below:
+
+     .. code-block:: python
+
+         class TestDummy(base.DummyBaseTest):
+
+             credentials = ['project_alt_reader']
+
+             @classmethod
+             def setup_clients(cls):
+                 super(TestDummy, cls).setup_clients()
+                 cls.az_p_alt_reader_client = (
+                     cls.os_project_alt_reader.availability_zone_client)
+
+  #. Project other roles: This is supported and can be requested and used from
+     the test as below:
+
+     You need to use the ``project`` as the prefix in credentials type, and
+     based on that, Tempest will create test users under 'project' scope.
+
+     .. code-block:: python
+
+         class TestDummy(base.DummyBaseTest):
+
+             credentials = [['project_my_role1', 'my_own_role1', 'admin']
+                            ['project_my_role2', 'my_own_role2']]
+
+             @classmethod
+             def setup_clients(cls):
+                 super(TestDummy, cls).setup_clients()
+                 cls.az_role1_client = (
+                     cls.os_project_my_role1.availability_zone_client)
+                 cls.az_role2_client = (
+                     cls.os_project_my_role2.availability_zone_client)
+
+Pre-Provisioned Credentials
+---------------------------
+
+Pre-Provisioned credentials support the below set of personas and can be
+used in the test as shown above in the ``Dynamic Credentials`` Section.
+
+* Domain Admin
+* Domain Member
+* Domain Reader
+* System Admin
+* System Member
+* System Reader
+* Project Admin
+* Project Member
+* Project Reader