Add the possibility to override the OS definition for enforcement.

There is an inline check for the Red Hat version of OpenStack that
ensure that the OS version matches the OpenStack version.

In the latest version of it we need to be able to temporarily change
the os version for some roles.

We implement this by defining a new role variable that will be
propagated to the ansible role responsible for the enforcement.

Note that when the rhsm_enforce_multios is defined, that create an
extra newline, but it doesn't break the resulting ansible playbook as
indentation is respected.

Depends-On: https://review.opendev.org/c/openstack/tripleo-ansible/+/891881
Change-Id: Ie9e789cb6367c7b1f96bf4f8a45aa08caa698fbc

common/deploy-steps.j2

@@ -987,6 +987,9 @@ outputs:
                 docker_puppet_mount_host_puppet: DOCKER_PUPPET_MOUNT_HOST_PUPPET
                 tripleo_minor_update: true
                 tripleo_redhat_enforce: {{role.rhsm_enforce|default("true")}}
+                {% if role.rhsm_enforce_multios is defined %}
+                tripleo_redhat_enforce_multios: {{role.rhsm_enforce_multios}}
+                {% endif %}
               tasks:
                 - import_tasks: hiera_steps_tasks.yaml
                 - import_tasks: common_container_config_scripts.yaml

roles/README.rst

@@ -78,6 +78,12 @@ Role Options
   check when it is not needed. Note that on non Red Hat environment
   this switch has no effect.
 
+* rhsm_enforce_multios: (string), optional, default to undefined, can be
+  set to "8.4" for instance. After a upgrade from 16.2 to 17.1 we can
+  be in a state where some compute roles are still on Red Hat 8.4. This
+  variable can be set to specify that value for those roles and
+  override the expected "9.2".
+
 Working with Roles
 ==================
 The tripleoclient provides a series of commands that can be used to view