[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.

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

Change-Id: I9d26b1b4a14360a8b38d6df19621b474c6391de9

handlers/main.yml

@@ -22,11 +22,11 @@
   listen:
     - "venv changed"
 
-- name: Remove legacy policy.json file
+# NOTE (noonedeadpunk): Remove this task after Xena release
+- name: Remove obsoleted policy.json file
   file:
-    path: "/etc/barbican/policy.json"
+    path: "{{ barbican_etc_directory }}/policy.json"
     state: absent
-  when:
-    - barbican_policy_overrides == {}
   listen:
     - Restart barbican services
+    - venv changed

tasks/barbican_post_install.yml

@@ -39,15 +39,27 @@
     - Restart barbican services
     - Restart uwsgi services
 
-- name: Implement policy.json if there are overrides configured
-  copy:
-    content: "{{ barbican_policy_overrides | to_nice_json }}"
-    dest: "{{ barbican_etc_directory }}/policy.json"
+- name: Implement policy.yaml if there are overrides configured
+  config_template:
+    content: "{{ barbican_policy_overrides }}"
+    dest: "{{ barbican_etc_directory }}/policy.yaml"
+    owner: "root"
+    group: "{{ barbican_system_group_name }}"
+    mode: "0640"
+    config_type: yaml
   when:
-    - barbican_policy_overrides != {}
-  notify:
-    - Restart barbican services
-    - Restart uwsgi services
+    - barbican_policy_overrides | length > 0
+  tags:
+    - barbican-policy-override
+
+- name: Remove legacy policy.yaml file
+  file:
+    path: "{{ barbican_etc_directory }}/policy.yaml"
+    state: absent
+  tags:
+    - barbican-policy-override
+  when:
+    - barbican_policy_overrides | length == 0
 
 - name: Copy user defined libraries
   when: barbican_user_libraries | length > 0