Hiera is a built-in key-value configuration data lookup system, used for separating data from Puppet code. About HieraPuppet’s strength is in reusable code. Code that serves many needs must be configurable: put site-specific information in external configuration data files, rather than in the code itself.Getting started with HieraThis page introduces the basic concepts and tasks to get you started with Hiera, including how to create a hiera.yaml config file and write data. It is the foundation for understanding the more advanced topics described in the rest of the Hiera documentation.Configuring HieraThe Hiera configuration file is called hiera.yaml. It configures the hierarchy for a given layer of data.Creating and editing dataImportant aspects of using Hiera are merge behavior and interpolation.Looking up data with HieraWriting new data backendsYou can extend Hiera to look up values in data sources, for example, a PostgreSQL database table, a custom web app, or a new kind of structured data file.Upgrading to Hiera 5Upgrading to Hiera 5 offers some major advantages. A real environment data layer means changes to your hierarchy are now routine and testable, using multiple backends in your hierarchy is easier and you can make a custom backend.