Master Nginx: Custom Error Pages, Status Monitoring, and Performance Tuning

Nginx is a high‑performance web and reverse‑proxy server that consumes little memory and handles high concurrency, making it a popular alternative to Apache for large Chinese internet companies such as Taobao, JD, Baidu, Sina, NetEase, and Tencent.

1. Customizing the 404 error page

Before optimization, accessing a non‑existent URL returns the default "404 Not Found" page. To define a custom error page, edit /usr/local/nginx/conf/nginx.conf and add error_page 404 /404.html;, then create the 404.html file and reload Nginx.

2. Viewing server status information

Compile Nginx with --with-http_stub_status_module to enable the status page. After enabling, add a location block:

location /status {
    stub_status on;
    #allow IP;
    #deny IP;
}

Reload Nginx and query curl http://<em>IP</em>/status to see active connections, accepts, handled, requests, reading, writing, and waiting counts.

3. Increasing concurrency

Run an ab load test and observe "Too many open files" errors. Increase worker_processes (typically to the number of CPU cores) and worker_connections 65535; in the events block, then reload.

Adjust Linux limits with ulimit -Hn 100000 and ulimit -Sn 100000, and persist them in /etc/security/limits.conf by setting * soft nofile 100000 and * hard nofile 100000.

4. Expanding client header buffers

When a long URL triggers a "414 Request‑URI Too Large" error, increase the buffers in the http block:

client_header_buffer_size 1k;
large_client_header_buffers 4 4k;

Reload Nginx and re‑run the script to verify the request succeeds.

5. Browser‑side static file caching

In Firefox, view the cache via about:cache. To set caching for static assets, add a location block matching common file extensions and specify expires 30d;:

location ~* \.(jpg|jpeg|gif|png|css|js|ico|xml)$ {
    expires 30d;
}

Place a test image in /usr/local/nginx/html, reload, and verify the cache headers in the browser.