Add CORS support (#478)

* Add optional CORS

* make CORS an extra dependency

* add documentation

caravel/__init__.py

@@ -46,6 +46,10 @@
                                        backupCount=app.config.get('BACKUP_COUNT'))
     logging.getLogger().addHandler(handler)
 
+if app.config.get('ENABLE_CORS'):
+    from flask.ext.cors import CORS
+    CORS(app, **app.config.get('CORS_OPTIONS'))
+
 
 class MyIndexView(IndexView):
     @expose('/')

caravel/config.py

@@ -132,6 +132,10 @@
 CACHE_DEFAULT_TIMEOUT = None
 CACHE_CONFIG = {'CACHE_TYPE': 'null'}
 
+# CORS Options
+ENABLE_CORS = False
+CORS_OPTIONS = {}
+
 
 # ---------------------------------------------------
 # List of viz_types not allowed in your environment

docs/installation.rst

@@ -28,7 +28,7 @@ the required dependencies are installed: ::
 
 For **Fedora** and **RHEL-derivatives**, the following command will ensure
 that the required dependencies are installed: ::
-    
+
     sudo yum upgrade python-setuptools
     sudo yum install gcc libffi-devel python-devel python-pip python-wheel openssl-devel
 
@@ -228,6 +228,20 @@ Note that you can run the ``caravel refresh_druid`` command to refresh the
 metadata from your Druid cluster(s)
 
 
+CORS
+-----
+
+The extra CORS Dependency must be installed:
+
+    caravel[cors]
+
+
+The following keys in `caravel_config.py` can be specified to configure CORS:
+
+
+* ``ENABLE_CORS``: Must be set to True in order to enable CORS
+* ``CORS_OPTIONS``: options passed to Flask-CORS (`documentation <http://flask-cors.corydolphin.com/en/latest/api.html#extension>`)
+
 Upgrading
 ---------
 

setup.py

@@ -39,6 +39,9 @@
         'sqlparse>=0.1.16, <0.2.0',
         'werkzeug>=0.11.2, <0.12.0',
     ],
+    extras_require={
+        'cors': ['Flask-Cors>=2.0.0'],
+    },
     tests_require=['coverage'],
     author='Maxime Beauchemin',
     author_email='maximebeauchemin@gmail.com',