Hi Raphael,
You can use 'pm2' (
https://www.npmjs.com/package/pm2) to manage your node processes.
1. Start the node applications from pm2 instead of vanilla node
pm2 start server.js --name=someName
2. Use the startup command (
http://pm2.keymetrics.io/docs/usage/startup/) to create a startup script with
pm2 startup
3. The above command will give you a new command (depending on your OS) to execute as sudo. Just copy, paste and execute that command
4. After this freeze your node process with
pm2 dump
This should do it!