Installing Varnish on CentOS 7.2 is pretty straight forward, start off by adding the epel-release repo.
yum install epel-release
With the repo added install Varnish
yum install varnish
service varnish start
Start Varnish at startup
chkconfig varnish on
That’s it, you’ve installed varnish, started the service and added the service to OS startup.
You’ll now need to configure Varnish, the configurations files are located at /etc/varnish