DevOps: Puppet, Docker, and Kubernetes

Using selectors and case statements

Although you could write any conditional statement using if, Puppet provides a couple of extra forms to help you express conditionals more easily: the selector and the case statement.

How to do it…

Here are some examples of selector and case statements:

1. Add the following code to your manifest:

   $systemtype = $::operatingsystem ? {
     'Ubuntu' => 'debianlike',
     'Debian' => 'debianlike',
     'RedHat' => 'redhatlike',
     'Fedora' => 'redhatlike',
     'CentOS' => 'redhatlike',
     default  => 'unknown',
   }
   
   notify { "You have a ${systemtype} system": }

2. Add the following code to your manifest:

   class debianlike { notify { 'Special manifest for Debian-like systems': } } class redhatlike { notify { 'Special manifest for RedHat-like systems': } ...