Allow running Flask Blueprints alongside Superset (#2337)

* Allowing environments to import Blueprints

* Docs entry

* Fix typos

docs/installation.rst

@@ -377,3 +377,28 @@ your environment.::
     npm run build
     cd $SUPERSET_HOME
     python setup.py install
+
+
+Blueprints
+----------
+
+`Blueprints are Flask's reusable apps <http://flask.pocoo.org/docs/0.12/blueprints/>`_.
+Superset allows you to specify an array of Blueprints
+an array of Blueprints in your ``superset_config`` module. Here's
+an example on how this can work with a simple Blueprint. By doing
+so, you can expect Superset to serve a page that says "OK"
+at the ``/simple_page`` url. This can allow you to run other things such
+as custom data visualization applications alongside Superset, on the
+same server.
+
+..code ::
+
+    from flask import Blueprint
+    simple_page = Blueprint('simple_page', __name__,
+                                    template_folder='templates')
+    @simple_page.route('/', defaults={'page': 'index'})
+    @simple_page.route('/<page>')
+    def show(page):
+        return "Ok"
+
+    BLUEPRINTS = [simple_page]

superset/__init__.py

@@ -29,6 +29,14 @@ app = Flask(__name__)
 app.config.from_object(CONFIG_MODULE)
 conf = app.config
 
+for bp in conf.get('BLUEPRINTS'):
+    try:
+        print("Registering blueprint: '{}'".format(bp.name))
+        app.register_blueprint(bp)
+    except Exception as e:
+        print("blueprint registration failed")
+        logging.exception(e)
+
 if conf.get('SILENCE_FAB'):
     logging.getLogger('flask_appbuilder').setLevel(logging.ERROR)
 

superset/config.py

@@ -286,6 +286,11 @@ if not CACHE_DEFAULT_TIMEOUT:
 # permission management
 SILENCE_FAB = True
 
+
+# Integrate external Blueprints to the app by passing them to your
+# configuration. These blueprints will get integrated in the app
+BLUEPRINTS = []
+
 try:
     if CONFIG_PATH_ENV_VAR in os.environ:
         # Explicitly import config module that is not in pythonpath; useful