22 Feb

How to enable Varnish in cPanel server

Varnish is a caching technology. Varnish is a web accelerator and also referred as HTTP accelerator or reverse HTTP proxy, which will significantly enhance the performance of your website. Varnish cache is really fast thereby, speed up the delivery depending on your architecture.

Varnish enhance your website’s performance. Varnish stores a copy of the page which is served by the web server the first time a user visits the website. Next time, when the user requests for the same page, varnish will serve the copy instead of serving it from the web server. Thus, your webserver needs to handle only less traffic and there by increase the website performance and also reduce the server load.

 

Working of Varnish Cache

Once Varnish is installed in your server, it will listen in the port 80. Make Apache to listen in any other port other than 80. When a client requests for a page in your website, Varnish will try to serve the page from its cache memory. This is cache hit. If the page is not in its cache memory, then Varnish will request to HTTP (Apache) to serve the page and caches it for future reference.

Features of Varnish

1. Reduces the server load
2. High speed (cache + stored in RAM)
3. Useful to gain more visitors

Installation

1. Make Apache listen in any other port other than 80. Here I am making Apache to listen in port 8080. It can be done in two ways. Either editing the httpd.conf file or editing the Tweak settings in WHM

a) Editing httpd.conf file

# vi /usr/local/apache/conf/httpd.conf

Locate the following line in /usr/local/apache/conf/httpd.conf file and change the port from 80 to 8080

Listen 0.0.0.0:80

Once edited, the Apache config file for “Listen” should be as follows:

# grep -iw listen /usr/local/apache/conf/httpd.conf
Listen 0.0.0.0:8080

OR

b) Editing WHM – Tweak settings

WHM > Tweak Settings > Apache non-SSL IP/port

Set the port to 8080 and save the settings.

# grep VARNISH_LISTEN_PORT /etc/sysconfig/varnish
VARNISH_LISTEN_PORT=80

5. Edit Varnish config: /etc/varnish/default.vcl . Correct the IP address in this file to your IP address and port to 80

backend default {
  .host = "YOUR IP ADDRESS";
  .port = "80";
}

6. Start Varnish service on your server

# chkconfig varnish on
# service varnish start
# service varnish start
Starting Varnish Cache:                                    [  OK  ]

That’s it!!

You can check this by using the netstat command.

#netstat -plan | grep :80

Example:

# netstat -plan | grep :80
tcp        0      0 0.0.0.0:80                  0.0.0.0:*                   LISTEN      15129/varnishd      
tcp        0      0 0.0.0.0:8080                0.0.0.0:*                   LISTEN      12897/httpd        

Now, you can start monitor your Varnish with varnishstat

 

If you need to change your Varnish configuration file and you can test the configuration before restarting Varnish service by

# varnishd -C -f /etc/varnish/default.vcl

Note: While doing “yum install varnish” if you are getting libedit error, then follow the steps below:

varnish-3.0.5-1.el5.centos.x86_64 from varnish-3.0 has depsolving problems
  --> Missing Dependency: libedit.so.0()(64bit) is needed by package varnish-3.0.5-1.el5.centos.x86_64 (varnish-3.0)
Error: Missing Dependency: libedit.so.0()(64bit) is needed by package varnish-3.0.5-1.el5.centos.x86_64 (varnish-3.0)
 You could try using --skip-broken to work around the problem
 You could try running: package-cleanup --problems
                        package-cleanup --dupes
                        rpm -Va --nofiles --nodigest
The program package-cleanup is found in the yum-utils package.

In this case, you need to install the libedit rpm which is suitable for your architecture. You can find the rpm from http://rpmfind.net/linux/rpm2html

# wget ftp://rpmfind.net/linux/dag/redhat/el5/en/x86_64/dag/RPMS/libedit-20090923-3.0_1.el5.rf.x86_64.rpm
# rpm -ivh libedit-20090923-3.0_1.el5.rf.x86_64.rpm

Example:

# rpm -ivh libedit-20090923-3.0_1.el5.rf.x86_64.rpm
warning: libedit-20090923-3.0_1.el5.rf.x86_64.rpm: Header V3 DSA signature: NOKEY, key ID 6b8d79e6
Preparing...                ########################################### [100%]
   1:libedit                ########################################### [100%]

Done!!!

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