Nginx Server Block Generator

In Nginx, a server block (the equivalent of an Apache "virtual host") is a configuration unit defined with the server { ... } directive that handles requests matching a given server_name/listen combination. On Debian/Ubuntu-based systems these blocks are typically written as files under /etc/nginx/sites-available/, and only the ones symlinked into /etc/nginx/sites-enabled/ are actually active.

The difference between serving a static site and reverse proxying is how the request is fulfilled. In static mode, Nginx reads files directly from the directory specified by root and serves them via try_files — there is no application server in between. In reverse proxy mode, Nginx doesn't handle the request itself; it forwards it with proxy_pass to an application server running in the background (e.g. a Node.js/Express app listening on 127.0.0.1:3000) and relays the response back to the client. This lets Nginx take care of TLS termination, compression, static-asset caching and load balancing, separate from the application.

The line proxy_set_header X-Forwarded-Proto $scheme; matters in particular: even though Nginx talks to the client over HTTPS, it usually forwards the request to the backend as plain HTTP. Without this header, the application may think the request arrived unencrypted, which can prevent secure cookies from being set, cause it to generate http:// redirects instead of https://, or trigger mixed-content errors. Most frameworks (Express, Django, Rails, etc.) read this header to determine the request's real protocol — though the app side also needs a "trust proxy"-style setting enabled for it to take effect.

Once you've generated the config, save it as /etc/nginx/sites-available/<domain>, then enable it with sudo ln -s /etc/nginx/sites-available/<domain> /etc/nginx/sites-enabled/. Before going live, always test the syntax with sudo nginx -t; if it reports no errors, apply the change with sudo systemctl reload nginx (reload, not restart, reapplies the configuration without dropping active connections).