• Gunicorn is an application server (Nginx is serving proxy to Gunicorn)
• sudo vim /etc/systemd/system/gunicorn.socket

  [Unit]
  Description=gunicorn socket
  
  [Socket]
  ListenStream=/run/gunicorn.sock
  
  [Install]
  WantedBy=sockets.target

• sudo vim /etc/systemd/system/gunicorn.service

  [Unit]
  Description=gunicorn daemon
  Requires=gunicorn.socket
  After=network.target
  
  [Service]
  User=USERNAME
  Group=www-data
  WorkingDirectory=/home/USERNAME/MY_PROJECT_DIR
  ExecStart=MY_PROJECT_PATH/bin/gunicorn \
            --access-logfile - \
            --workers 3 \
            --bind unix:/run/gunicorn.sock \
            MY_PROJECT.wsgi:application
  
  [Install]
  WantedBy=multi-user.target

• sudo systemctl start gunicorn.socket
• sudo systemctl enable gunicorn.socket
• sudo systemctl status gunicorn.socket
• file /run/gunicorn.sock, output should be: /run/gunicorn.sock: socket, if some issues, check sudo journalctl -u gunicorn.socket and look at /etc/systemd/system/gunicorn.socket to fix some problems
• sudo systemctl status gunicorn - Active: inactive (dead)
• curl --unix-socket /run/gunicorn.sock localhost - output should be some html
• sudo systemctl status gunicorn - Active: active (running), if some issues, check sudo journalctl -u gunicorn and /etc/systemd/system/gunicorn.service and if you will make any changes, reload the daemon sudo systemctl daemon-reload and sudo systemctl restart gunicorn

Resources:

➡️https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-django-with-postgres-nginx-and-gunicorn

➡️https://www.digitalocean.com/community/tutorials/how-to-deploy-a-local-django-app-to-a-vps

➡️https://docs.gunicorn.org/

➡️http://rahmonov.me/posts/run-a-django-app-with-nginx-and-gunicorn/

➡️https://www.digitalocean.com/community/tutorials/how-to-set-up-django-with-postgres-nginx-and-gunicorn-on-debian-9