Provide a way of serving static files via gunicorn
While using Nginx is preferable from a performance point of view, using gunicorn with whitenoise is just as fast for our needs and comes with certain benefits that simplify the deployment of new instances since everything can be bundled in on container.
An alternative approach would be to install Nginx into the container and expose the static files via a separate port. I think it makes no difference an would violate the one service per container idea of Docker.