Imported from terminalskills/skills (skills/nginx/SKILL.md). Install upstream with npx skills add terminalskills/skills --skill nginx. Copyright stays with the author (Apache-2.0).

Nginx

Overview

Nginx is a high-performance web server and reverse proxy that serves static files, proxies requests to application servers, load balances across backends, terminates TLS, and caches responses. It handles thousands of concurrent connections with minimal resource usage through an event-driven, non-blocking architecture.

Instructions

• When configuring server blocks, define virtual hosts with server_name for domain matching and listen for ports, using separate blocks for HTTP (port 80, redirect to HTTPS) and HTTPS (port 443 with SSL and HTTP/2).
• When setting up reverse proxying, use proxy_pass to forward to upstream servers and set proxy_set_header for Host, X-Real-IP, X-Forwarded-For, and X-Forwarded-Proto to preserve client information.
• When load balancing, define upstream blocks with multiple servers and choose the strategy: round-robin (default), least_conn, ip_hash for sticky sessions, or weighted distribution.
• When configuring TLS, set modern protocols (TLSv1.2 TLSv1.3), enable ssl_stapling and session caching, and integrate with Let's Encrypt via certbot for automatic certificate renewal.
• When serving static files, enable gzip compression for text-based content, set expires 1y for hashed assets, use sendfile on for efficient transfer, and try_files for SPA fallback routing.
• When adding security, set headers (X-Frame-Options, X-Content-Type-Options, HSTS, CSP) and configure rate limiting with limit_req_zone to prevent abuse.

Examples

Example 1: Set up Nginx as reverse proxy with TLS for a Node.js app

User request: "Configure Nginx with HTTPS to proxy to my Node.js API on port 3000"

Actions:

1. Create a server block listening on port 443 with SSL certificate paths and HTTP/2
2. Configure proxy_pass http://localhost:3000 with proper header forwarding
3. Add a port 80 server block that redirects all HTTP to HTTPS
4. Enable ssl_stapling, session caching, and modern cipher suites

Output: An Nginx configuration with TLS termination, HTTP-to-HTTPS redirect, and reverse proxy to the Node.js app.

Example 2: Configure load balancing with health checks

User request: "Load balance across three API servers with failover"

Actions:

1. Define an upstream block with three backend servers and least_conn strategy
2. Set max_fails=3 fail_timeout=30s for automatic health checking
3. Add a backup server that activates only when primary servers are down
4. Configure proxy caching for GET requests to reduce backend load

Output: A load-balanced setup with automatic failover, health checks, and response caching.

Guidelines

• Use server_name with specific domains; avoid the _ catch-all in production for security.
• Always redirect HTTP to HTTPS with return 301 https://$host$request_uri on the port 80 block.
• Set security headers on every server block using an included snippet file for consistency.
• Use try_files for SPA routing instead of rewrite since it is faster and more explicit.
• Rate-limit API endpoints with limit_req zone=api burst=20 nodelay to prevent abuse without affecting normal traffic.
• Cache static assets aggressively: expires 1y for hashed filenames and expires 1h for HTML.
• Always test config before reload: nginx -t && nginx -s reload to prevent downtime from syntax errors.