.. _hacks:

Hacks
=====

In this document you will find some of the hacks users of Scout have come up with to do novel things.

Most of these techniques involve wrapping the Scout server application with an additional module. Since Scout server is a normal Python module, and the WSGI app is just an object within that module, there is no magic needed to extend the behavior of Scout.

Adding CORS headers
-------------------

I wanted to be able to query my Scout index from JavaScript running on a different host. To get this working I needed to add some special headers to each response from the API (`more info on CORS <https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS>`_).

To accomplish this I created a wrapper module that wraps the Scout server Flask app and implements a special ``after_request`` hook:

Here is the wrapper module:

.. code-block:: python

    from scout.server import parse_options

    app = parse_options()

    @app.after_request
    def add_cors_header(response):
        response.headers['Access-Control-Allow-Origin'] = 'http://myhost.com'
        response.headers['Access-Control-Allow-Headers'] = 'key,Content-Type'
        response.headers['Access-Control-Allow-Methods'] = 'GET,POST,DELETE'
        return response

Adding logging
--------------

To log exceptions within the Scout server, I created a wrapper for the Scout server WSGI app and added a handler to Flask's built-in app logger.

Here is the wrapper code:

.. code-block:: python

    import logging
    import os

    from scout.server import parse_options

    app = parse_options()

    cur_dir = os.path.realpath(os.path.dirname(__file__))
    log_dir = os.path.join(cur_dir, 'logs')

    handler = logging.FileHandler(os.path.join(log_dir, 'scout-error.log'))
    handler.setLevel(logging.ERROR)
    app.logger.addHandler(handler)