A working demo of Hiera with YAML and Puppet backends.

This demo consists of:

• A NTP module that has defaults for pool.ntp.org servers
• A common data module where module users can create override data in pp files
• A YAML data source in etc/hieradb where users can override data in yaml files
• A couple of users modules that just notify the fact that they are being included
• In Hiera data files a key called classes that decides what to include on a node

Below various usage scenarios can be tested using this module.

The examples below assume you have Hiera already installed and that you have hiera-puppet cloned from github and running these commands in hiera-puppet/example as cwd.

Module from forge with module defaults

• Move the modules/data directory to modules/data.bak to avoid overrides used further in the example
• Run puppet, creates /etc/ntp.conf with ntp.org addresses
• The hiera_include() function includes just users::common

$ mv modules/data modules/data.bak
$ puppet apply --config etc/puppet.conf site.pp
notice: /Stage[main]/Ntp::Config/File[/tmp/ntp.conf]/ensure: defined content as '{md5}7045121976147a932a66c7671939a9ad'
notice: /Stage[main]/Users::Common/Notify[Adding users::common]/message: defined 'message' as 'Adding users::common'
$ cat /tmp/ntp.conf
server 1.pool.ntp.org
server 2.pool.ntp.org

Site wide override data in data::common

• Restore the modules/data directory that has a class data::common that declares site wide overrides
• The hiera_include() function includes just users::common

$ mv modules/data.bak modules/data
$ puppet apply --config etc/puppet.conf site.pp
notice: /Stage[main]/Ntp::Config/File[/tmp/ntp.conf]/content: content changed '{md5}7045121976147a932a66c7671939a9addc2' to '{md5}8f9039fe1989a278a0a8e1836acb8d23'
notice: /Stage[main]/Users::Common/Notify[Adding users::common]/message: defined 'message' as 'Adding users::common'
$ cat /tmp/ntp.conf
server ntp1.example.com
server ntp2.example.com

Fact driven overrides for location=dc1

• Set a fact location=dc1 that uses the YAML data in etc/hieradb/dc1.yaml to override
• Show that machines in dc2 would use site-wide defaults
• The hiera_include() function includes users::common and users::dc1 as the data file for dc1 adds that

$ FACTER_location=dc1 puppet apply --config etc/puppet.conf site.pp
notice: /Stage[main]/Ntp::Config/File[/tmp/ntp.conf]/content: content changed '{md5}8f9039fe1989a278a0a8e1836acb8d23' to '{md5}074d0e2ac727f6cb9afe3345d574b578'
notice: /Stage[main]/Users::Common/Notify[Adding users::common]/message: defined 'message' as 'Adding users::common'
notice: /Stage[main]/Users::Dc1/Notify[Adding users::dc1]/message: defined 'message' as 'Adding users::dc1'
$ cat /tmp/ntp.conf
server ntp1.dc1.example.com
server ntp2.dc1.example.com

Now simulate a machine in dc2, because there is no data for dc2 it uses the site wide defaults and does not include the users::dc1 class anymore

$ FACTER_location=dc2 puppet apply --config etc/puppet.conf site.pp
warning: Could not find class data::dc2 for nephilim.ml.org
notice: /Stage[main]/Ntp::Config/File[/tmp/ntp.conf]/content: content changed '{md5}074d0e2ac727f6cb9afe3345d574b578' to '{md5}8f9039fe1989a278a0a8e1836acb8d23'
notice: /Stage[main]/Users::Common/Notify[Adding users::common]/message: defined 'message' as 'Adding users::common'
$ cat /tmp/ntp.conf
server ntp1.example.com
server ntp2.example.com

You could create override data in the following places for a machine in location=dc2, they will be searched in this order and the first one with data will match.

• file etc/hieradb/dc2.yaml
• file etc/hieradb/common.yaml
• class data::dc2
• class data::production
• class data::common
• class ntp::config::data
• class ntp::data

In this example due to the presence of common.yaml that declares ntpservers the classes will never be searched, it will have precedence.