Nginx reverse proxy to Node.js app with correct headers

When proxying requests from nginx to a Node.js backend, the app sees 127.0.0.1 as the client IP and incorrect protocol/host headers, breaking features that depend on real client information.

Set proxy headers explicitly in the nginx location block:

server {
    listen 80;
    server_name example.com;

    location / {
        proxy_pass http://127.0.0.1:3000;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        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;
        proxy_cache_bypass $http_upgrade;
    }
}

In Express, trust the proxy:

app.set('trust proxy', 1);
// Now req.ip returns the real client IP

Nginx rewrites headers when proxying. Without these headers, the backend cannot determine the real client IP or whether the original request was HTTPS.