Place the below file in /lib/systemd/system/jupyterhub.service.
Then, run systemctl daemon-reload and start the service with service jupyterhub start. This will need to be done as root.
The file below runs as root, but you'll likely want to specify a more restricted User and WorkingDirectory. You may also need to add to the path in the Environment arg.
Additional environmental variables, like "GITHUB_CLIENT_ID", can be added with more Environment="VAR=value" lines.