def init_app(cls, app):
        ProductionConfig.init_app(app)

        # handle reverse proxy server headers
        try:
            from werkzeug.middleware.proxy_fix import ProxyFix
        except ImportError:
            from werkzeug.contrib.fixers import ProxyFix
        app.wsgi_app = ProxyFix(app.wsgi_app)

        # log to stderr
        import logging
        from logging import StreamHandler
        file_handler = StreamHandler()
        file_handler.setLevel(logging.INFO)
        app.logger.addHandler(file_handler)