Unable to retrieve files from send_from_directory() in flask

Question

I have a html file which references static object like this

Answer 1

Don't use Flask's built-in server in production. It is for development only! And don't use Flask to serve static assets. It's slow! In production use a webserver in front of Flask like apache2, nginx or lighttpd. These servers are able to rewrite a URL and serve static assets.

How to deploy Flask: http://flask.pocoo.org/docs/deploying/

How to rewrite a URL: apache2, nginx, lighttpd.