Hiera allows you to create a hierarchy of node information. Using Hiera, you can separate your variables and data from your modules. You start by defining what that hierarchy will be, by ordering lookups in the main configuration file,
hiera.yaml. The hierarchy is based on facts. Any fact can be used, even your own custom facts may be used. The values of the facts are then used as values for the YAML files stored in a directory, usually called
hieradata. More information on Hiera can be found on the Puppet Labs website at http://docs.puppetlabs.com/hiera/latest.
Facts are case sensitive in Hiera and templates. This could be important when writing your
Hiera only needs to be installed on your Puppet master ...