Create yaml file of the zuul job vars for embedded ansible

Drop copies of the 'zuul' dict from the executor ansible into
files which can be read later by the embedded ansible.

Change-Id: I756af31f9afeaccb44498c39d0e55200d4844544

zuul.d/playbooks/pre-gate-scenario.yml

@@ -23,6 +23,7 @@
     install_methods:
       - distro
       - source
+    zuul_user_vars_file: "{{ ansible_env.HOME }}/osa-job-vars.yml"
   tasks:
     - name: Dynamically create scenario if not set
       set_fact:
@@ -110,3 +111,13 @@
         src: osa-gate-scenario.yml.j2
         dest: "{{ zuul.executor.work_root }}/osa-gate-scenario.yml"
       delegate_to: localhost
+
+    # Other playbooks can consume this vars file to access the
+    # Zuul job variables, see https://zuul-ci.org/docs/zuul/reference/jobs.html#user-jobs-job-variables
+    - name: Record the zuul user job variables for future use by embedded ansible
+      vars:
+        zuul_helper_var:
+          zuul: "{{ zuul }}"
+      template:
+        src: osa-job-vars.yml.j2
+        dest: "{{ zuul_user_vars_file }}"

zuul.d/playbooks/templates/osa-gate-scenario.yml.j2

@@ -2,4 +2,5 @@
 
 scenario: {{ scenario | to_json }}
 action: {{ action | to_json }}
-install_method: {{ install_method | to_json }}
+install_method: {{ install_method | to_json }}
+zuul_user_vars_file: {{ zuul_user_vars_file }}

zuul.d/playbooks/templates/osa-job-vars.yml.j2

@@ -0,0 +1,2 @@
+---
+{{ zuul_helper_var | to_nice_yaml(indent=2) }}