[goal] Deprecate the JSON formatted policy file

As per the community goal of migrating the policy file
the format from JSON to YAML[1], we need to replace policy.json to
policy.yaml and remove deprecated policy.json.

config_template has been choosen instead of the copy, since it can
properly handle content that has been lookuped.

We make a separate task not to restart service when it's not needed.

[1] https://governance.openstack.org/tc/goals/selected/wallaby/migrate-policy-format-from-json-to-yaml.html

Change-Id: I3ff3ce4f150854ece690f1bcbd7183f511fccf2e

handlers/main.yml

@@ -60,6 +60,15 @@
     - "Restart nova services"
     - "venv changed"
 
+# NOTE (noonedeadpunk): Remove this task after Xena release
+- name: Remove obsoleted policy.json
+  file:
+    path: "/etc/nova/policy.json"
+    state: absent
+  listen:
+    - "Restart nova services"
+    - "venv changed"
+
 - name: Start services
   service:
     name: "{{ item.service_name }}"

tasks/nova_post_install.yml

@@ -81,16 +81,26 @@
     - nova-config
     - nova-post-install
 
-- name: Implement policy.json if there are overrides configured
-  copy:
-    content: "{{ nova_policy_overrides | to_nice_json }}"
-    dest: "/etc/nova/policy.json"
+- name: Implement policy.yaml if there are overrides configured
+  config_template:
+    content: "{{ nova_policy_overrides }}"
+    dest: "/etc/nova/policy.yaml"
+    owner: "root"
+    group: "{{ nova_system_group_name }}"
+    mode: "0640"
+    config_type: yaml
   when:
-    - nova_policy_overrides != {}
-  notify:
-    - Manage LB
-    - Restart nova services
-    - Restart uwsgi services
+    - nova_policy_overrides | length > 0
+  tags:
+    - nova-config
+    - nova-policy-override
+
+- name: Remove legacy policy.yaml file
+  file:
+    path: "/etc/nova/policy.yaml"
+    state: absent
+  when:
+    - nova_policy_overrides | length == 0
   tags:
     - nova-config
     - nova-policy-override