Sunday, October 12, 2014

Installing Varnish With Virtualmin

Varnish Logo

What is Varnish

Varnish is an HTTP accelerator and a reverse proxy caching web application.

Varnish is usually installed in front of the webserver such as Apache and Nginx, and cache their content in order to deliver it fast when a request is made.

I couldn't find any good tutorial on installing varnish with virtualmin so I decided to test and post about it.
Varnish Explanation

Installing dependencies

yum install -y gcc make automake autoconf libtool ncurses-devel libxslt groff pcre-devel libedit libedit-devel

Varnish 4 requires jemalloc to work
rpm -Uvh

Installing Varnish

The below is for CentOS 6. Varnish for other distros can be found on

Login to SSH, and issue the following commands:

rpm -Uvh
yum install varnish

Configuring varnish

Varnish is installed in front of the webserver, so it should listen on port 80 to accept the web requests.
vi /etc/sysconfig/varnish

Varnish Listening Port

Since varnish will be listening on port 80, the webserver will have to listen on a different port. In this tutorial, I will use port 8080.

So varnish will fetch the content from the webserver, and cache it. In order for varnish to know which port the webserver is listening to, we modify /etc/varnish/default.vcl
vi /etc/varnish/default.vcl
And set the port to 8080. Then set the IP to your server's external IP. Setting it to will not work on virtualmin by default, since virtualmin uses the external IP when creating a virtual host.
(Replace by your external IP)
Apache and Varnish listening ports

Changing Virtualhosts to new Web server port (8080)

If you already have virtualhosts created, you will have to modify them all, one by one, by going to:
Virtual Server => Server Configuration => Change IP Address => Set New HTTP port to 8080
changing the port of virtualhost in virtualmin for varnish

Change the port the webserver is listening to:

Webmin => Servers => Apache Webserver => Make sure all the virtual hosts are not listening on port 80
Go to Global Configuration Tab => Network and Configuration => Remove ALL the entries that has port 80 in it.
Make sure is your IP Address

Restart the Servers:

service httpd restart
service varnish restart

All your sites should now be running.

Configure Varnish to Start after a Reboot

Go to Webmin => System => Bootup and Shutdown => Choose Varnish => Click Start on Boot
Configuring varnish to start after a reboot

Edit Server Templates

Edit the Server templates, so that the next time you create a new virtual host, it will be listening on port 80.
Virtualmin => System Settings => Server Templates => Default Settings => Apache Website => Change "Port number for virtual hosts" to 8080 and then click "Save".

Editing virtualmin template for apache in order for varnish to work

If you have more custom templates, you will need to edit them all.

Check Varnish Performance

In SSH type:

In this tutorial, I'm using Apache as a webserver, but it should work well on Nginx or any other webserver.

Any questions? Please let me know!