Setting node-specific data with Hiera

In our hierarchy defined in hiera.yaml, we created an entry based on the hostname fact; in this section, we'll create yaml files in the hosts subdirectory of Hiera data with information specific to a particular host.

Getting ready

Install and configure Hiera as in the last section and use the hierarchy defined in the previous recipe that includes a hosts/%{hostname} entry.

How to do it...

The following are the steps:

1. Create a file at /etc/puppet/hieradata/hosts that is the hostname of your test node. For example if your host is named cookbook-test, then the file would be named cookbook-test.yaml.
2. Insert a specific message in this file:

   message: 'This is the test node for the cookbook'

3. Run Puppet on two different test nodes to note the difference:

   t@ckbk:~$ sudo puppet agent -t
   Info: Caching catalog for cookbook-test
   Notice: Message is This is the test node for the cookbook
   [root@hiera-test ~]# puppet agent -t
   Info: Caching catalog for hiera-test.example.com
   Notice: Message is Default Message
   

How it works...

Hiera searches the hierarchy for files that match the values returned by facter. In this case, the cookbook-test.yaml file is found by substituting the hostname of the node into the search path /etc/puppet/hieradata/hosts/%{hostname}.yaml.

Using Hiera, it is possible to greatly reduce the complexity of your Puppet code. We will use yaml files for separate values, where previously you had large case statements or nested if statements.