Varnish Cache is an open-source, elite HTTP accelerator agent. It stores the cache in memory ensuring that web server resources are not wasted in creating the same web page over and over again when requested by a client. Here we are going to look at how a varnish cache can be installed and configured to act as a front-end to Apache HTTP server.
Prerequisites:
- CentOS 7
- A root user or user with sudo privileges
Step 1: Installing Apache Web Server
[root@server ~]# yum install httpd
Step 2: Once Apache is installed start it for time being and enable it to start automatically at system boot.
[root@server ~]# systemctl start httpd [root@server ~]# systemctl enable httpd [root@server ~]# systemctl status httpd
httpd.service – The Apache HTTP Server
Loaded: loaded (/usr/lib/systemd/system/httpd.service; enabled; vendor preset: disabled)
Active: active (running) since Fri 2019-03-01 07:22:15 EST; 1h 15min ago
Step 3: Enable the EPEL repository to install several dependency packages
yum install -y epel-release
Step 4: Install pygpgme, a package for handling GPG signatures and yum-utils, a collection of useful utilities that extend yum’s native features in various ways.
yum install pygpgme yum-utils
Step 5: Create a file named /etc/yum.repos.d/varnish5.repo and add the below configurations
[varnishcache_varnish5] name=varnishcache_varnish5 baseurl=https://packagecloud.io/varnishcache/varnish5/el/7/$basearch repo_gpgcheck=1 gpgcheck=0 enabled=1 gpgkey=https://packagecloud.io/varnishcache/varnish5/gpgkey sslverify=1 sslcacert=/etc/pki/tls/certs/ca-bundle.crt metadata_expire=300 [varnishcache_varnish5-source] name=varnishcache_varnish5-source baseurl=https://packagecloud.io/varnishcache/varnish5/el/7/SRPMS repo_gpgcheck=1 gpgcheck=0 enabled=1 gpgkey=https://packagecloud.io/varnishcache/varnish5/gpgkey sslverify=1 sslcacert=/etc/pki/tls/certs/ca-bundle.crt metadata_expire=300
Make sure to replace el and 7 in the config below with your Linux distribution and version:
Step 6: Update local yum cache
yum -q makecache -y --disablerepo='*' --enablerepo='varnishcache_varnish5'
Step 7: Install Varnish Cache
yum install varnish
varnish configuration files are located in /etc/varnish/ [root@server ~]# cd /etc/varnish/ [root@server varnish]# ll total 12 -rw-r--r-- 1 root root 1231 Mar 1 07:20 default.vcl -rw------- 1 root root 37 Mar 1 07:12 secret -rw-r--r-- 1 root root 1347 Mar 1 07:18 varnish.params
– /etc/varnish/varnish.params – This is the varnish environment configuration file.
-/etc/varnish/default.vcl – This is the main varnish configuration file. It is written using varnish configuration language(VCL).
– /etc/varnish/secret – This is varnish secret file.
Step 8: Confirm Varnish installation by seeing the location of the Varnish executable and version installed on your system.
[root@server varnish]# which varnishd /usr/sbin/varnishd [root@server varnish]# varnishd -V varnishd (varnish-5.2.1 revision 67e562482) Copyright (c) 2006 Verdens Gang AS Copyright (c) 2006-2015 Varnish Software AS
Step 9 : Configuring Apache to Work With Varnish Cache
Apache usually listens to port 80 by default. In order to ensure that Apache runs behind varnish, change the default httpd port to 8080. This can be done easily by using the sed command.
sed -i "s/Listen 80/Listen 8080/" /etc/httpd/conf/httpd.conf
Step 10: Open the varnish environment configuration file (/etc/varnish/varnish.params) and find the parameter VARNISH_LISTEN_PORT which specifies the port Varnish listens on, and change its value from 6081 to 80.
vi /etc/varnish/varnish.params
# Default address and port to bind to. Blank address means all IPv4
# and IPv6 interfaces, otherwise specify a host name, an IPv4 dotted
# quad, or an IPv6 address in brackets.
# VARNISH_LISTEN_ADDRESS=192.168.1.5
VARNISH_LISTEN_PORT=80
Step 11: Setup Apache as a backend server for Varnish proxy
Edit the main varnish configuration file (/etc/varnish/default.vcl). By default it is shown below.
Below is the default backend configuration, set this to point to your actual content server.
backend default {
.host = "127.0.0.1";
.port = "8080";
}
Set this to point to your content server.
backend default {
.host = "136.243.201.227";
.port = "8080";
}
Step 11: Restart httpd and Varnish cache to effect the above changes.
systemctl restart httpd systemctl start varnish systemctl enable varnish systemctl status varnish
Step 12: Test Varnish Cache on Apache
[root@server ~]# curl -I server.training5.com
Date: Fri, 01 Mar 2019 14:28:42 GMT
Server: Apache/2.4.6 (CentOS)
Last-Modified: Thu, 16 Oct 2014 13:20:58 GMT
ETag: “1321-5058a1e728280”
Accept-Ranges: bytes
Content-Length: 4897
Content-Type: text/html; charset=UTF-8
X-Varnish: 32776
Age: 0
Via: 1.1 varnish (Varnish/5.2)
Connection: keep-alive
