Scope

This skill covers the software layer — what runs inside a machine. For infrastructure (provisioning VMs, SSH hardening, firewalls, backups), use the vps skill.

When to Use

• Configuring nginx, Caddy, or Apache
• Deploying Node.js, Python, Go, or other apps
• Docker and Docker Compose setups
• SSL/TLS certificates with Let's Encrypt
• Reverse proxy and load balancing
• Process management (pm2, systemd services)
• Troubleshooting port conflicts, CORS, connection errors
• Self-hosting (Plex, Nextcloud, game servers)
• Local development servers (Vite, webpack-dev-server)

Common Pitfalls

• Port already in use — Check with lsof -i :PORT or ss -tlnp | grep PORT, kill stale processes
• CORS in development — Proxy through your dev server or configure backend headers, don't disable in production
• SSL certificate issues — Certbot needs port 80/443 open, use --standalone or --webroot mode appropriately
• nginx config not loading — Always run nginx -t before systemctl reload nginx
• Docker container can't reach host — Use host.docker.internal (Docker Desktop) or 172.17.0.1 (Linux)
• Process dies after SSH disconnect — Use systemd, pm2, or run inside tmux/screen
• Wrong permissions on mounted volumes — Match container user UID with host file ownership

Patterns by Use Case

For framework-specific configs, see configs.md. For Docker Compose patterns, see docker.md.

Debugging Checklist

1. Is the process running? systemctl status or docker ps
2. Is it listening? ss -tlnp | grep PORT
3. Can you reach it locally? curl localhost:PORT
4. Firewall blocking? Check ufw status or cloud security groups
5. Reverse proxy misconfigured? Check nginx logs: /var/log/nginx/error.log
6. DNS pointing correctly? dig domain.com or nslookup