Reverse proxy to your API

📘What it really is

• Your Node.js API listens only on the server itself (127.0.0.1:3001); Nginx forwards API requests to it:

location /v1/ {
    proxy_pass http://127.0.0.1:3001;
    proxy_set_header Host $host;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;
}

• Benefits:
• the frontend and API share one domain, so no CORS and simpler cookies (Module 50, Lesson 2);
• only Nginx faces the internet; the API's port stays closed to the outside (Lesson 5);

• Nginx handles HTTPS, slow clients and limits, so Node.js doesn't have to.

• Trust proxy: the app now sees every request coming from Nginx (127.0.0.1). Set Express's app.set("trust proxy", 1) so it reads the real visitor address from X-Forwarded-For, which rate limiting (Module 48) and logs need. Only trust headers from your own proxy.

• Nginx can also load balance across several copies of the app (upstream blocks), useful later (Module 70).

• WebSockets (real-time features) need two extra headers (Upgrade and Connection); add them if your app uses them.