Enable CORS for data/* (#1922)

* Test Flask-Cors

* Add a CORS test for data/*

framework/basehandlers.py

@@ -41,6 +41,7 @@ import django
 
 from google.auth.transport import requests
 from flask import session
+from flask_cors import CORS
 import sys
 
 # Initialize django so that it'll function when run as a standalone script.
@@ -515,6 +516,9 @@ def FlaskApplication(import_name, routes, pattern_base='', debug=False):
   # Flask apps also have a debug setting that can be used to auto-reload
   # template source code, but we use django for that.
 
+  # Set the CORS HEADERS.
+  CORS(app, resources={r'/data/*': {'origins': '*'}})
+
   # Set cookie headers in Flask; see
   # https://flask.palletsprojects.com/en/2.0.x/config/
   # for more details.

requirements.txt

@@ -16,6 +16,7 @@ requests==2.27.1
 # TODO(jrobbins): Update to a 2.x version of flask, which may require source
 # code changes.
 Flask==1.1.2
+flask-cors==3.0.10
 funcsigs==1.0.2
 Jinja2==2.11.3
 MarkupSafe==1.1.1