Enable overriding the service setup host python interpreter

In order to enable the service setup host python interpreter to
be changed easily, we make it a variable. This will be useful
when someone sets the service setup host to be the utility
container, because we'll be able to set this var by default.

Change-Id: I3e0034739c75ca72bad4b33819e774e5c85977ac

defaults/main.yml

@@ -22,6 +22,7 @@ cinder_pip_package_state: "latest"
 # for the service setup. The host must already have
 # clouds.yaml properly configured.
 cinder_service_setup_host: "{{ openstack_service_setup_host | default('localhost') }}"
+cinder_service_setup_host_python_interpreter: "{{ openstack_service_setup_host_python_interpreter | default((cinder_service_setup_host == 'localhost') | ternary(ansible_playbook_python, ansible_python['executable'])) }}"
 
 # Set installation method.
 cinder_install_method: "source"

tasks/cinder_service_setup.yml

@@ -21,8 +21,7 @@
 - name: Setup the service
   delegate_to: "{{ cinder_service_setup_host }}"
   vars:
-    ansible_python_interpreter: >-
-      {{ (cinder_service_setup_host == 'localhost') | ternary(ansible_playbook_python, ansible_python['executable']) }}
+    ansible_python_interpreter: "{{ cinder_service_setup_host_python_interpreter }}"
   block:
     - name: Add services to the keystone service catalog
       os_keystone_service: