Varnish is a web application accelerator. You install it in front of your web application to cache generated HTML files and serve them faster. It will take a lot of burden from your web application and can even provide you with extended uptime—covering up for application failures through its cache while you are fixing your application.
Let's see how to install Varnish.
You need a web server running on your node at port 8080. We'll set up Varnish to use localhost:8080 as its backend host and port. You can achieve this by installing a Ruby on Rails application on your node as described in the Managing Ruby on Rails applications recipe.
Make sure that you have a cookbook called my_cookbook and that the run_list of your node includes my_cookbook as described in the Creating and using cookbooks recipe in Chapter 1, Chef Infrastructure.
Create Berksfile in your Chef repository including my_cookbook:
mma@laptop:~/chef-repo $ subl Berksfile
cookbook 'my_cookbook', path...