DevOps: Puppet, Docker, and Kubernetes

Iterating over multiple items

Arrays are a powerful feature in Puppet; wherever you want to perform the same operation on a list of things, an array may be able to help. You can create an array just by putting its content in square brackets:

$lunch = [ 'franks', 'beans', 'mustard' ]

How to do it…

Here's a common example of how arrays are used:

1. Add the following code to your manifest:

   $packages = [ 'ruby1.8-dev',
     'ruby1.8',
     'ri1.8',
     'rdoc1.8',
     'irb1.8',
     'libreadline-ruby1.8',
     'libruby1.8',
     'libopenssl-ruby' ]
   
   package { $packages: ensure => installed }

2. Run Puppet and note that each package should now be installed.

How it works…

Where Puppet encounters an array as the name of a resource, it creates a resource for each element in the array. In the example, ...