About Varnish
Varnish is an HTTP accelerator and a useful tool for speeding up a server, especially during a times when there is high traffic to a site. It works by redirecting visitors to static pages whenever possible and only drawing on the virtual private server itself if there is a need for an active process.
Setup
To perform the steps in this tutorial, you will need to both have a user with sudo privileges and apache installed on your virtual private server.
To create a user with sudo privileges, go through the third and fourth steps of the initial ubuntu server setup tutorial
Apache can be installed on your VPS with a single command from the apt-get repository.
sudo apt-get install apache2
Step One—Install Varnish
The varnish site recommends installing the varnish package through their repository.
You can start that process by grabbing the repository:
sudo curl http://repo.varnish-cache.org/debian/GPG-key.txt | sudo apt-key add -
The next step is to add the repository to the list of apt sources. Go ahead and open up that file.
sudo nano /etc/apt/sources.list
Once inside the file, add the varnish repository to the list of sources.
deb http://repo.varnish-cache.org/ubuntu/ lucid varnish-3.0
Save and exit.
Finally, update apt-get and install varnish.
sudo apt-get update sudo apt-get install varnish
Step Two—Configure Varnish
Once you have both apache and varnish installed, you can start to configure them to ease the load on your server from future visitors.
Varnish will serve the content on port 80, while fetching it from apache which will run on port 8080.
Let’s go ahead and start setting that up by opening the /etc/default/varnish file:
sudo nano /etc/default/varnish
Uncomment all of the lines under “DAEMON_OPTS”—under Alternative 2, and make the configuration match the following code:
DAEMON_OPTS="-a :80 \
-T localhost:6082 \
-f /etc/varnish/default.vcl \
-S /etc/varnish/secret \
-s malloc,256m"
Once you save and exit out of that file, open up the default.vcl file:
sudo nano /etc/varnish/default.vcl
This file tells varnish where to look for the webserver content. Although Apache listens on port 80 by default, we will change the settings for it later. Within this file, we will tell varnish to look for the content on port 8080. The configuration should like this:
backend default {
.host = "127.0.0.1";
.port = "8080";
}
Step Three—Configure Apache
So far we have told varnish that apache ports will be running on 8080. However the default settings for apache are still on port 80. We will correct the discrepancy now.
Open up the apache ports file:
sudo nano /etc/apache2/ports.conf
Change the port number for both the NameVirtualHost and the Listen line to port 8080, and the virtual host should only be accessible from the localhost. The configuration should look like this:
NameVirtualHost 127.0.0.1:8080 Listen 127.0.0.1:8080
Change these settings in the default virtual host file as well:
sudo nano /etc/apache2/sites-available/default
The Virtual Host should also be set to port 8080, and updated line looks like this:
<VirtualHost 127.0.0.1:8080>
Save and exit the file and proceed to restart Apache and Varnish to make the changes effective.
sudo service apache2 restart sudo service varnish restart
Accessing your domain should instantly take you to the varnish cached version, and you can see the details of varnish’s workings with this command:
varnishstat
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