Gunicorn now supports SSL, as of version 17.0. You can configure it to listen on https like this:
$ gunicorn --certfile=server.crt --keyfile=server.key test:app
If you were using --bind to listen on port 80, remember to change the port to 443 (the default port for HTTPS connections). For example:
$ gunicorn --certfile=server.crt --keyfile=server.key --bind 0.0.0.0:443 test:app