Introduction to Hiera and Hiera Data Structures. I presented this as the DevOps Tech In Motion Meetup in San Francisco on 9/26.

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

2. 2 © Jive confidential
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