This guide explains how to install and configure Varnish Cache on EL9-based systems when using CWP (CentOS Web Panel) with the Apache + Nginx + Varnish stack.

⚠️ Important Note

On AlmaLinux 9 / RockyLinux 9 / RHEL 9, Varnish may not install automatically via CWP.
This guide provides a manual workaround to install and configure it correctly.

✅ Step 1: Install Web Server Stack from CWP

Login to CWP Admin Panel

Go to:

WebServer Settings → Select WebServers

Choose:

Apache + Nginx + Varnish

Click Save & Rebuild Configuration

👉 At this stage, Varnish may appear as missing — proceed to Step 2.

✅ Step 2: Install Varnish Manually

Run the following commands:

dnf install -y epel-release
curl -s https://packagecloud.io/install/repositories/varnishcache/varnish66/script.rpm.sh | sudo bash
dnf install -y varnish

✅ Step 3: Change Varnish Port (6081 → 82)

Edit the Varnish systemd service file:

nano /usr/lib/systemd/system/varnish.service

🔍 Find this line:

ExecStart=/usr/sbin/varnishd -a :6081 ...

✏️ Replace with:

ExecStart=/usr/sbin/varnishd -a :82 -f /etc/varnish/default.vcl -s malloc,256m

✅ Step 4: Reload & Start Varnish

Run:

systemctl daemon-reexec
systemctl daemon-reload
setenforce 0
systemctl restart varnish

🔍 Verify Varnish is running:

ss -tulnp | grep varnish
systemctl status varnish

🔒 (Optional) Protect Configuration File

Lock the service file to prevent CWP overwriting:

chattr +i /usr/lib/systemd/system/varnish.service

To unlock later:

chattr -i /usr/lib/systemd/system/varnish.service

✅ Step 5: Fix Backend Configuration (Important)

If your website shows 503 Backend fetch failed, update Varnish backend.

Edit:

nano /etc/varnish/default.vcl

🔍 Replace this:

backend default {
    .host = "127.0.0.1";
    .port = "8080";
}

✅ With your server IP and Apache port:

backend default {
    .host = "YOUR_SERVER_IP";
    .port = "8181";
}

Example:

.host = "109.50.345.14";

🔒 (Optional) Protect VCL file:

chattr +i /etc/varnish/default.vcl

Unlock if needed:

chattr -i /etc/varnish/default.vcl

✅ Step 6: Restart Varnish

systemctl restart varnish

✅ Step 7: Test Your Website

Visit your website in a browser.

✔ Website should load normally
✔ No more 503 Backend fetch failed errors

🧪 Optional: Verify Varnish is Working

curl -I http://yourdomain.com

Look for:

Via: 1.1 varnish

🔥 Final Architecture

⚠️ Troubleshooting Tips

Ensure Apache is running on port 8181

Disable SELinux temporarily if issues occur:

setenforce 0

Check logs:

systemctl status varnish
journalctl -xe

✅ Conclusion

By following this guide, you can successfully install and configure Varnish Cache on EL9 systems with CWP, even though it is not fully supported natively.