I want to make a Flask+Nginx+Gunicorn deployment. I have Nginx setup and running and I run gunicorn as described in the docs:
gunicorn app:app
I tried the systemd option and it worked fine, the link below has my full answer and has all the steps , to invoke your app as a gunicorn service.
https://askubuntu.com/questions/930589/running-upstart-script-on-17-04/1010398#1010398