How to apply decorator to every Flask view
To add headers to every outgoing response, use the @Flask.after_request hook instead:
@app.after_requestdef add_ua_compat(response): response.headers['X-UA-Compatible'] = 'IE=Edge' return responseThere is a Flask extension that does exactly this; register the hook and add a header.
You might consider just writing a custom WSGI middleware. You can snag all of your application's responses and augment the headers as necessary. The quickstart discusses how to hook in a middleware and there are no shortage of WSGI tutorials on how to add headers to the start_response