README.md

Lab 11.1: Configure hiera

Hiera is a data separation layer that allows you to write classes that can easily adapt to customizations per node, per operating system, per environment, or any other facts. This allows the class logic to be straightforward and transparent, while still allowing extreme customizability. Even more so, it allows the end user to simply classify each node and specify parameters using Hiera rules, making the classification process less complicated.

Hiera is a tool that runs on the Puppet master, but it is useful to have a representative data configuration on your local dev workstation for testing. In the classroom, we've set up a local Hiera configuration to pull data from /etc/puppetlabs/code/hieradata/. In this lab, you configure the Hiera hierarchy and create datasources; observing how data retrieval works.

Looking up data with puppet lookup passes the local scope (facts for the local node) for us automatically. To look up data for another node, simply specify that node's name with the --node <node name> argument.

Customers on the Long Term Support release can use puppet apply -e '(notice(lookup("keyname")))' to perform a similar local lookup.

As the final step to this lab, you will commit your datasources to your repository, then push them to the Puppet master. Test that the data retrieval functions still works when running the Puppet agent.

Steps

Configure Hiera with a common datasource

1. Edit the hiera configuration file.
   • cd /etc/puppetlabs/puppet
   • Edit hiera.yaml
   • set the hierarchy to query trusted.certname, environment, common
2. Edit common.yaml in the Hiera datadir.
   • cd /etc/puppetlabs/code
   • Edit hieradata/common.yaml
   • Take note of the value of the message key, or edit as desired.

Retrieve data from Hiera

1. Use the puppet lookup command to display the value of that key

   puppet lookup message

Configure more levels in the hierarchy

You can retrieve your hostname using Facter

`facter hostname`

Your output should look similar to this `1954nix0.classroom.puppet.com`

1. Create a studentN.yaml in the Hiera datadir.
   • Edit control-repo/data/studentN.yaml
   • Add a message key and set its value to value from StudentN
   • Test the hierarchy override by executing the same Puppet code as before.
2. Create hostname in the hiera datadir.
   • Edit control-repo/data/nodes/hostname.yaml
   • Add a message key and set the value to hostname
   • Test the hierarchy override by running the same lookup command as before.

Deploy and test your datasources

1. Windows Instructions: migrate your datasources to your control repository
   • Copy & paste each file into the corresponding file in your control repository.
   • Edit [control-repo]/hieradata/common.yaml
   • Edit [control-repo]/hieradata/nodes/hostname.yaml
2. Add a notify resource to your site.pp to display the message.
   • Edit ~/control-repo/manifests/site.pp
3. Deploy your code.
4. Validate the output of your message.
   • puppet agent -t
   • You should observe the same message output.

Solution

Example file ~/control-repo/hiera.yaml

---
version: 5

defaults:
  datadir: "data"
hierarchy: 
  - name: Yaml data
    data_hash: yaml_data
    paths:
      - "nodes/%{::trusted.certname}.yaml"
      - "%{environment}.yaml"
      - "common.yaml"

Note: an equivalent Hiera3 file for LTS versions would be:

---
:backends:
    - yaml

:yaml:
    :datadir: /etc/puppetlabs/code/hieradata

:hierarchy:
    - "%{::trusted.certname}"
    - "%{environment}"
    - common

Example file ~/control-repo/hieradata/common.yaml

---
message: 'value from common'

Example file: ~/control-repo/hieradata/studentN.yaml

---
message: 'value from StudentN'

Example file: ~/control-repo/hieradata/hostname.yaml

---
message: 'value from hostname'

Example file: ~/control-repo/manifests/site.pp

node default {
  # ...
  $message = lookup('message')
  notify { $message: }
}

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