This document introduces Hiera, a key/pair lookup tool for Puppet that helps manage node data hierarchically and reduces data repetition. It provides an overview of Hiera's installation, configuration (hiera.yaml), and data structures including variables, arrays, and hashes. The presentation aims to clarify Hiera's role within Puppet and demonstrate practical examples for setting it up effectively.

1. Introduction to Hiera &
Basic Hiera Data
Structures
David Kramer, RHCA
Sr. DevOps Manager

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Introduction to Hiera Agenda
• Quick intro about myself
• What is this presentation and what isn’t it?
• Overview of Puppet
• Overview of Hiera
• Overview of Hiera Data Structures
• Tying it all together

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Overview of Puppet
• What is Puppet?
– Should I mention facter?
• How do we manage nodes in Puppet?
– Every node always gets a node object
• Nodes.pp
• ENC
– Node_terminus
• Hiera
• Common question Im asked, can you have
multiple ENC’s? Yes you can!

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What is Hiera?
• Hiera is a Key/Pair lookup tool
• Provides an Environment Hierarchy within
your data roles
• Reduces data repetition
– Write data for most scenarios
– Allows you to focus on difference data!
• Allows you to specify node specific data
– Provides Hierarchical Overriding

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Brief Installation Overview of Hiera
• Package Info
– Hiera Gem
– Puppet 2.7.x needs hiera-puppet package installed.
– Puppet 3.0+ does not need hiera-puppet, hiera is
native!
• /etc/puppet/hiera.yaml
– Role Hierarchy definitions
• Modify your sites.pp to be hiera aware!
– classes: - hiera_include('classes')
– parameterized_classes: –
hiera_hash(‘parameterized_classes’ )

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Walking thru the hiera.yaml
• :backends:
– Yaml
– Json
• :datadir:
– :yaml /etc/puppet/hieradata
• :gpg:
– Tired of storing secret information in the clear?
• :hierarchy:
– %{::clientcert}
– roles/%{role}

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Hierarchy for your Environments
• Meta Data, Meta Data, Meta Data
– Custom Facts using Facter.add
• This is all up to you!!
• Some Jivin examples:
– Data Center
– Deployment Environment –Your SDLC!
– Roles

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Overview of Hiera Data Structures
• Hiera Variable
– hiera(‘variable name’,’empty’)
• Hiera Array
– hiera_array( ‘array name’, ‘empty’)
• Hiera Hashes
– hiera_hash(‘hash name’, ‘empty’)

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Yaml Data Structure Examples
• Yaml Variable:
• Yaml Array:

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Yaml Data Structure Examples
• Yaml Hash:

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Hooking your Yaml into your Puppet 
• Tying all of this together by making your
Puppet Class Hiera aware:

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Questions?

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http://docs.puppetlabs.
com/hiera/1/index.html
http://www.yaml.org/YA
ML_for_ruby.html#sim
ple_sequence
Resources