A working demo of Hiera with YAML backend.

This demo consists of:

• A NTP module that has defaults for pool.ntp.org servers
• A YAML data source in the data/ directory where users can override data in yaml files
• A Users module that has a few manifests that simply notify 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 the puppet-agent already installed
• You have this repository cloned from github
• Are running these commands from within the examples/hiera directory as cwd.

Module from forge with module defaults

• Comment out lines 6-8 of data/common.yaml to avoid overrides used further in the example
• Run a puppet apply to create a /tmp/ntp.conf file containing the two pool.ntp.org addresses
• The users::common class should also be present in your catalog

$ sed -i '6,8 s/^/#/' data/common.yaml
$ puppet apply site.pp --hiera_config=hiera.yaml --modulepath=modules
Notice: Compiled catalog for node.corp.com in environment production in 0.04 seconds
Notice: Adding users::common
Notice: /Stage[main]/Users::Common/Notify[Adding users::common]/message: defined 'message' as 'Adding users::common'
Notice: /Stage[main]/Ntp::Config/File[/tmp/ntp.conf]/ensure: defined content as '{sha256}949c7247dbe0870258c921418cc8b270afcc57e1aa6f9d9933f306009ede60d0'
Notice: Applied catalog in 0.02 seconds
$ cat /tmp/ntp.conf
server 1.pool.ntp.org
server 2.pool.ntp.org

Site wide override data in data::common

• Remove the comments on lines 6-8 of data/common.yaml
• Run a puppet apply to update /tmp/ntp.conf to contain the two ntp.example.com addresses
• The users::common class should also be present in your catalog

$ sed -i '6,8 s/^#//' data/common.yaml
$ puppet apply site.pp --hiera_config=hiera.yaml --modulepath=modules
Notice: Compiled catalog for node.corp.com in environment production in 0.04 seconds
Notice: Adding users::common
Notice: /Stage[main]/Users::Common/Notify[Adding users::common]/message: defined 'message' as 'Adding users::common'
Notice: /Stage[main]/Ntp::Config/File[/tmp/ntp.conf]/content: content changed '{sha256}949c7247dbe0870258c921418cc8b270afcc57e1aa6f9d9933f306009ede60d0' to '{sha256}28ced955a8ed9efd7514b2364fe378ba645ab947f26e8c0b4d84e8368f1257a0'
Notice: Applied catalog in 0.02 seconds
$ cat /tmp/ntp.conf
server ntp1.example.com
server ntp2.example.com

Fact driven overrides for location=dc1

• Override the location fact to dc1 to demonstrate data/dc1.yaml overrides the ntp::config::ntpservers values in data/common.yaml
• dc1 nodes will
  • have the users::common and users::dc1 in their catalogs
  • /tmp/ntp.conf will contain the two ntp.dc1.example.com addresses
• Show that the nodes in dc2 would use the site-wide defaults

$ FACTER_location=dc1 puppet apply site.pp --hiera_config=hiera.yaml --modulepath=modules
Notice: Compiled catalog for node.corp.com in environment production in 0.04 seconds
Notice: Adding users::dc1
Notice: /Stage[main]/Users::Dc1/Notify[Adding users::dc1]/message: defined 'message' as 'Adding users::dc1'
Notice: Adding users::common
Notice: /Stage[main]/Users::Common/Notify[Adding users::common]/message: defined 'message' as 'Adding users::common'
Notice: /Stage[main]/Ntp::Config/File[/tmp/ntp.conf]/content: content changed '{sha256}28ced955a8ed9efd7514b2364fe378ba645ab947f26e8c0b4d84e8368f1257a0' to '{sha256}39227f1cf8d09623d2e66b6622af2e8db01ab26f77a5a2e6d6e058d0977f369b'
Notice: Applied catalog in 0.02 seconds
$ 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 site.pp --hiera_config=hiera.yaml --modulepath=modules
Notice: Compiled catalog for node.corp.com in environment production in 0.04 seconds
Notice: Adding users::common
Notice: /Stage[main]/Users::Common/Notify[Adding users::common]/message: defined 'message' as 'Adding users::common'
Notice: /Stage[main]/Ntp::Config/File[/tmp/ntp.conf]/content: content changed '{sha256}39227f1cf8d09623d2e66b6622af2e8db01ab26f77a5a2e6d6e058d0977f369b' to '{sha256}28ced955a8ed9efd7514b2364fe378ba645ab947f26e8c0b4d84e8368f1257a0'
Notice: Applied catalog in 0.02 seconds
$ 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 data/dc2.yaml
• file data/<environment>.yaml
• file data/common.yaml

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