Add os_tempest documentation

The review adds documentation regarding of execution os_tempest on top of
a TripleO deployment provided by one of the TripleO CI jobs.

Depends-On: https://review.openstack.org/#/c/639147/

Change-Id: Iea467ae4c15a8484fa034fcaca186d82474dbabf

doc/source/install/basic_deployment/os_tempest.rst

@@ -0,0 +1,74 @@
+os_tempest
+==========
+
+TripleO CI group collaborates on `os_tempest` development. To see what
+`os_tempest` is and the reasons why it was started have a look
+`at this page <https://docs.openstack.org/openstack-ansible-os_tempest/latest/overview.html>`_.
+
+At this moment we run `os_tempest` in `tripleo-ci-centos-7-standalone-os-tempest`
+job where it is used for cloud validation.
+
+To find out more about `os_tempest` default variables follow to its
+`official documentation <https://docs.openstack.org/openstack-ansible-os_tempest/latest/user/default.html>`_
+
+
+Create your own os_tempest job
+-------------------------------
+
+We are going to use `tripleo-ci-centos-7-standalone-os-tempest` job, which
+uses the role for validating the cloud.
+
+Create a job definition in your `.zuul.yaml` file putting
+`tripleo-ci-centos-7-standalone-os-tempest` as a parent of the job:
+
+.. code-block:: yaml
+
+    - job:
+        name: our-tripleo-os-tempest-job
+        parent: tripleo-ci-centos-7-standalone-os-tempest
+
+.. note::
+
+    More about Zuul job definitions can be found in
+    `the official Zuul documentation <https://zuul-ci.org/docs/zuul/user/config.html>`_.
+
+.. note::
+
+    This page assumes that the reader is familier with
+    `TripleO CI jobs <https://docs.openstack.org/tripleo-docs/latest/ci/ci_primer.html>`_
+    and with the procedures of
+    `adding new TripleO jobs <https://docs.openstack.org/tripleo-docs/latest/ci/check_gates.html>`_.
+
+By default, `tripleo-ci-centos-7-standalone-os-tempest` sets the following
+variables for controlling behaviour of `os_tempest`:
+
+.. code-block:: yaml
+
+    vars:
+        tempest_install_method: distro
+        tempest_cloud_name: 'standalone'
+
+and runs `tempest.yaml` playbook which sets the rest of the `os_tempest`
+variables needed for execution on top of an environment deployed by one of the
+TripleO CI jobs. The
+`content of the playbook can be seen here <https://git.openstack.org/cgit/openstack/tripleo-quickstart-extras/tree/playbooks/tempest.yml>`_.
+
+If you want to set some of the variables mentioned above differently you need
+to override them by adding those variables to your job definition.
+
+Let's say you would like to change `tempest_cloud_name` and
+`tempest_public_net_physical_type`. After setting the variables your job
+definition should look like:
+
+.. code-block:: yaml
+
+    - job:
+        name: our-tripleo-os-tempest-job
+        parent: tripleo-ci-centos-7-standalone-os-tempest
+        vars:
+            tempest_cloud_name: <your cloud name>
+            tempest_public_net_physical_type: <your net type>
+
+To see configuration options, please, follow
+`this page <https://docs.openstack.org/openstack-ansible-os_tempest/latest/user/configuration.html>`_
+of official documentation of `os_tempest` role.

doc/source/install/index.rst

@@ -12,6 +12,7 @@ TripleO Install Guide
   basic_deployment/basic_deployment_ui
   basic_deployment/tempest
   basic_deployment/tempest_plugins
+  basic_deployment/os_tempest
   containers_deployment/index
   post_deployment/post_deployment
   advanced_deployment/features