Optimizing Gzip and Brotli Compression on VPS with EA-Nginx: The Complete Admin Guide for CloudLinux + cPanel Servers Print

🚀 Ultimate Guide to Enabling Gzip & Brotli Compression on VPS with EA-Nginx (CloudLinux + cPanel)

A practical, copy‑paste friendly guide for VPS admins running CloudLinux + cPanel/WHM with EA‑Nginx reverse proxy. Covers global gzip/Brotli, cache purge, verification, CDN interplay, and a full troubleshooting checklist.

📝 TL;DR (Admin Quick Start)

# 1) Enable proxy‑layer gzip (safe types only)
cat >/etc/nginx/conf.d/zz-gzip.conf <<'NGX'
# Global gzip for text assets (safe, server-wide)
gzip on;
gzip_disable "msie6";
gzip_comp_level 5;
gzip_min_length 512;
gzip_vary on;
gzip_proxied any;
# Only text-based types (do NOT include images or woff2)
gzip_types text/plain text/css text/xml text/javascript \
  application/javascript application/x-javascript application/json \
  application/xml application/rss+xml application/ld+json image/svg+xml \
  application/vnd.ms-fontobject application/x-font-ttf application/x-font-opentype \
  application/font-woff font/ttf font/otf;
NGX

# 2) (Optional) Enable Brotli (if modules present)
ls -1 /usr/lib64/nginx/modules/ | egrep 'brotli_(filter|static)_module\.so' || true
if ! nginx -T 2>/dev/null | grep -q 'ngx_http_brotli_filter_module'; then
  cp -a /etc/nginx/nginx.conf{,.bak-$(date +%F-%H%M%S)}
  sed -i '1iload_module modules/ngx_http_brotli_static_module.so;' /etc/nginx/nginx.conf
  sed -i '1iload_module modules/ngx_http_brotli_filter_module.so;' /etc/nginx/nginx.conf
fi
cat >/etc/nginx/conf.d/zz-brotli.conf <<'NGX'
brotli on;
brotli_comp_level 4;
brotli_static on;  # if .br files exist; harmless otherwise
brotli_types text/plain text/css application/json application/javascript \
  text/xml application/xml application/rss+xml image/svg+xml;
NGX

# 3) Test & reload Nginx
nginx -t && (/scripts/restartsrv_nginx || systemctl reload nginx)

# 4) Purge proxy cache once (paths may vary)
CACHE_DIR=$(nginx -T 2>/dev/null | awk '/proxy_cache_path/ {print $2}' | sed 's/;.*//')
[ -n "$CACHE_DIR" ] && rm -rf "$CACHE_DIR"/* 2>/dev/null || rm -rf /var/cache/nginx/* 2>/dev/null
/scripts/restartsrv_nginx || systemctl reload nginx

# 5) Verify (HTML + real CSS/JS)
for url in \
  https://example.com/ \
  https://example.com/wp-includes/css/dist/block-library/style.min.css
do
  echo -e "\n==> $url"; curl -sI -H 'Accept-Encoding: gzip,br' "$url" | egrep -i 'HTTP/|server:|content-type:|content-encoding:|vary:'; done

Expect: Content-Encoding: br or gzip + Vary: Accept-Encoding.

🔍 Why .htaccess Isn’t Enough in EA-Nginx

Apache's DEFLATE via .htaccess only applies if Apache handles the response. EA-Nginx often caches and serves content without Apache, making .htaccess ineffective.

✅ Solution: Enable Nginx-level compression and purge the proxy cache.

🤖 Stack Detection & Brotli Availability

Check:

/scripts/restartsrv_nginx --status || systemctl status nginx
nginx -V 2>&1 | egrep -i 'nginx version|brotli|modules'

Look for:

• EA-Nginx present: /scripts/restartsrv_nginx works

• Brotli: modules exist under /usr/lib64/nginx/modules/

🛠️ Enable Gzip & Brotli Compression (Safe Types)

• Create /etc/nginx/conf.d/zz-gzip.conf and /zz-brotli.conf

• Load Brotli modules if available

• Reload Nginx safely

• Purge proxy cache

Compression Levels:

• gzip_comp_level 4-5

• brotli_comp_level 3-5

Never compress binary types (images, WOFF2, archives).

🔎 Verification Methods

cURL

curl -I -H 'Accept-Encoding: gzip,br' https://example.com/

Check for:

• Content-Encoding: br/gzip

• Vary: Accept-Encoding

Browser

• DevTools → Network Tab

• Look for headers in HTML/CSS/JS

🤔 Common Pitfalls

• gzip off; in later includes: nginx -T | grep -n 'gzip\s\+(on|off);'

• CDN like Cloudflare overriding with its compression: enable Speed → Brotli

• Testing 404s or binary files: always verify real, existing assets

📊 Performance Notes

• Compression is cached = minimal CPU impact

• Only for text-based assets

• Vary: Accept-Encoding ensures CDN/client compatibility

🚀 Rollout & Rollback Procedures

Rollout

# Add .conf files
# Load brotli modules (if needed)
# Reload nginx
# Purge cache

Monitoring

top -o %CPU
journalctl -u nginx -n 200 --no-pager

Rollback (Instant)

mv /etc/nginx/conf.d/zz-brotli.conf{,.disabled}
mv /etc/nginx/conf.d/zz-gzip.conf{,.disabled}
sed -i '/load_module modules\/ngx_http_brotli_.*_module.so;/d' /etc/nginx/nginx.conf
nginx -t && (/scripts/restartsrv_nginx || systemctl reload nginx)

🔧 Troubleshooting Checklist

1. Confirm Nginx serving (check Server: header)

2. Test real assets (avoid 404s/images)

3. Ensure Content-Encoding and Vary present

4. Purge proxy cache

5. Check for gzip off; in config includes

6. Validate CDN settings (Cloudflare Brotli, etc.)

7. Check app/plugin compression overrides

8. Confirm correct subdomain docroots

9. Set gzip_comp_level 1 temporarily if needed

10. Inspect Nginx logs

🖊️ One-Liner: Verify Any Domain

domain=example.com
for u in "https://$domain/" \
         "https://$domain/wp-includes/css/dist/block-library/style.min.css"; do
  echo "$u";
  curl -sI -H 'Accept-Encoding: gzip,br' "$u" | egrep -i 'HTTP/|server:|content-type:|content-encoding:|vary:';
  echo;
done

🌐 Appendix: "Optimize Website" in cPanel

It’s safe to keep Apache DEFLATE enabled in cPanel, but EA-Nginx compression is what actually matters for client performance.