nginx Config Builder

A server block defines a virtual host — it listens on a port and matches a domain name. A location block lives inside a server block and matches request paths (e.g. /api/, /static/). You can have multiple location blocks per server block to route different paths to different backends or apply different rules.

Use proxy_pass to forward requests to a backend (Node.js, Python, etc.). Use root to set the base directory for serving static files — the full path is root + URI. Use alias to map a location path to a different filesystem path, replacing the location prefix rather than appending to root.

When nginx acts as a reverse proxy, it forwards requests to your backend. Without extra headers, the backend sees nginx's address, not the real client IP. proxy_set_header X-Real-IP $remote_addr passes the original client IP. Use $http_x_forwarded_for if there's a load balancer in front of nginx.

WebSocket upgrades require two extra headers: proxy_set_header Upgrade $http_upgrade and proxy_set_header Connection 'upgrade'. Also set proxy_http_version 1.1 since WebSockets require HTTP/1.1. Without these, nginx closes the connection and WebSocket handshake fails.

try_files checks a list of files/paths in order. try_files $uri $uri/ /index.html is the classic SPA pattern: try the exact file, then a directory index, then fall back to index.html. This enables client-side routing for React, Vue, Angular apps served from nginx.

Place snippets in /etc/nginx/sites-available/mysite.conf. Then enable: sudo ln -s /etc/nginx/sites-available/mysite.conf /etc/nginx/sites-enabled/. Test: sudo nginx -t. Reload: sudo systemctl reload nginx. On some systems, you include from /etc/nginx/conf.d/ instead.