Convert from empty strings to Nones for better defaults

These will also be skipped in the yaml file unless set which better
enables app defaults in XQueue

CHANGELOG.md

+- Role: XQueue
+  - Convert to a yaml config (instead of xqueue.auth.json and xqueue.env.json we get xqueue.yml and it lives by default in /edx/etc/xqueue.yml like standard IDAs)
+  - Add XQUEUE_DEFAULT_FILE_STORAGE so that you can specify S3 or Swift in your config
+
 - Role: credentials
   - Set `LANGUAGE_COOKIE_NAME` so that Credentials will use the global language cookie.
 

playbooks/roles/xqueue/defaults/main.yml

@@ -21,22 +21,25 @@ XQUEUE_SYSLOG_SERVER: 'localhost'
 
 XQUEUE_UPLOAD_BUCKET: 'sandbox-bucket'
 XQUEUE_UPLOAD_PATH_PREFIX: 'sandbox-xqueue'
+# You can set this to S3 or Swift, but it will
+# default to the django file storage for tests/devstacks
+XQUEUE_DEFAULT_FILE_STORAGE: !!null
 
 XQUEUE_LOCAL_LOGLEVEL: 'INFO'
 
 # If you try to use an Instance IAM Role rather than a user key S3 will invalidate the signed
 # URLs used in uploaded file submissions.  If you don't upload files on grade submissions, then
 # it's ok, the submission is stored directly in the database.
-XQUEUE_AWS_ACCESS_KEY_ID : ''
-XQUEUE_AWS_SECRET_ACCESS_KEY : ''
+XQUEUE_AWS_ACCESS_KEY_ID : !!null
+XQUEUE_AWS_SECRET_ACCESS_KEY : !!null
 
-XQUEUE_SWIFT_USERNAME: ''
-XQUEUE_SWIFT_KEY: ''
-XQUEUE_SWIFT_TENANT_ID: ''
-XQUEUE_SWIFT_TENANT_NAME: ''
-XQUEUE_SWIFT_AUTH_URL: ''
-XQUEUE_SWIFT_AUTH_VERSION: 1
-XQUEUE_SWIFT_REGION_NAME: ''
+XQUEUE_SWIFT_USERNAME: !!null
+XQUEUE_SWIFT_KEY: !!null
+XQUEUE_SWIFT_TENANT_ID: !!null
+XQUEUE_SWIFT_TENANT_NAME: !!null
+XQUEUE_SWIFT_AUTH_URL: !!null
+XQUEUE_SWIFT_AUTH_VERSION: !!null
+XQUEUE_SWIFT_REGION_NAME: !!null
 
 XQUEUE_BASIC_AUTH_USER: "{{ COMMON_HTPASSWD_USER }}"
 XQUEUE_BASIC_AUTH_PASSWORD: "{{ COMMON_HTPASSWD_PASS }}"
@@ -79,6 +82,7 @@ XQUEUE_CONFIG:
   LOCAL_LOGLEVEL: "{{ XQUEUE_LOCAL_LOGLEVEL }}"
   UPLOAD_BUCKET: "{{ XQUEUE_UPLOAD_BUCKET }}"
   UPLOAD_PATH_PREFIX: "{{ XQUEUE_UPLOAD_PATH_PREFIX }}"
+  DEFAULT_FILE_STORAGE: "{{ XQUEUE_DEFAULT_FILE_STORAGE }}"
   NEWRELIC_APPNAME: "{{ XQUEUE_NEWRELIC_APPNAME }}"
   SUBMISSION_PROCESSING_DELAY: "{{ XQUEUE_SUBMISSION_PROCESSING_DELAY }}"
   CONSUMER_DELAY: "{{ XQUEUE_CONSUMER_DELAY }}"