Flask: Set header on static files

Question

I've got the following flask route which serves static content:

@app.route('/static/<path:path>')
@resourceDecorator
def getStaticFile(path):
    return send_from_directory('static', path)

@resourceDecorator is declared as follows:

def resourceDecorator(f):
    def new_func(*args, **kwargs):
        resp = make_response(f(*args, **kwargs))

        resp.cache_control.no_cache = True                   # Turn off caching
        resp.headers['Access-Control-Allow-Origin'] = '*'    # Add header to allow CORS

        return resp
    return update_wrapper(new_func, f)

The decorator sets headers to deactivate caching and allow cross domain access. This works for my other, "regular" routes, but the files sent through the static route do not seem to get their headers set.

What's going wrong here?

Answer 1

For static files, flask sets the default cache timeout to 12 hours/43200s hence your problem. You can change the default cache timeout in send_from_directory by passing the cache_timeout value directly since it uses the send_file function to send a file to a client.

send_from_directory(cache_timeout=0)

Alternatively you can override the get_send_file_max_age.