Puppet 5 Beginner's Guide - Third Edition

The hierarchy

So far, we've only used a single Hiera data source (common.yaml). Actually, you can have as many data sources as you like. Each usually corresponds to a YAML file, and they are listed in the hierarchy section of the hiera.yaml file, with the highest-priority source first and the lowest last:

hierarchy:
  ...
  - name: "Host-specific data"
    path: "nodes/%{facts.hostname}.yaml"
  - name: "OS release-specific data"
    path: "os/%{facts.os.release.major}.yaml"
  - name: "OS distro-specific data"
    path: "os/%{facts.os.distro.codename}.yaml"
  - name: "Common defaults"
    path: "common.yaml"

In general, though, you should keep as much data as possible in the common.yaml file, simply because it's easier to find and maintain data if it's in one place, rather ...