Proxying to Node, and keeping it alive

Get a current Node

apt install nodejs gives you something ancient. Pull the real source first:

curl https://deb.nodesource.com/setup_19.x | sudo -E bash -
sudo apt-get install nodejs
node --version

Stop needing sudo for your own files

/var/www isn't yours, which is why the earlier vi trap happened. Take it:

sudo chown -R $USER:$USER /var/www    # change owner, recursively
mkdir /var/www/app && cd /var/www/app
git init
npm init
touch app.js

The application

This time write straight to the response instead of reading a file:

const http = require("http")

http.createServer(function (req, res) {
    res.write("On the way to being a full stack engineer")
    res.end()
}).listen(3000)

console.log("server started")

res.end() isn't optional. Without it the server never signals that the response is finished, so nothing is sent.

The virtual server

nginx can host any number of virtual servers on one machine. Rather than editing the default config, make your own:

sudo vi /etc/nginx/sites-enabled/fsfe

server_name doesn't matter while this is the catch-all, but it will the moment you add subdomains — that's what nginx matches the incoming request against.

Then point nginx at only this file: edit /etc/nginx/nginx.conf and remove the line including sites-enabled/default, so you're not fighting the default config later.

sudo nginx -t                 # validate before you break anything
sudo service nginx restart

nginx -t checks every config file without applying it. Run it every time. It needs sudo because it touches the log files.

Keep it running

Start the app and it works. Close your terminal and the site goes down — the shell exits and takes the process with it.

sudo npm i -g pm2
pm2 start app.js --watch
pm2 list
pm2 save                      # remember the current process list
pm2 startup                   # prints a command — run it, it registers with systemd

That's the whole chain: a domain, a server you hardened yourself, nginx in front, Node behind it, kept alive across reboots. From here it's npm install and territory you already know.