More than one static path in local Flask instance [duplicate]

I have been using following approach:

# Custom static data
@app.route('/cdn/<path:filename>')
def custom_static(filename):
    return send_from_directory(app.config['CUSTOM_STATIC_PATH'], filename)

The CUSTOM_STATIC_PATH variable is defined in my configuration.

And in templates:

{{ url_for('custom_static', filename="foo") }}

Caveat emptor – I’m not really sure whether it’s secure 😉