file_backend.rb

file_backend.rb

Puppet::Functions.create_function(:'file_backend') do
  dispatch :file_backend do
    param "String", :key
    param "Hash", :options
    param "Puppet::LookupContext", :context
  end
  def file_backend(key, options, context)
    if (options.key?("directory"))
      dir = context.interpolate(options["directory"])
      if (File.exists?("#{dir}/#{key}")
        data = File.read("#{dir}/#{key}")
      else
        context.not_found
      end
    else
      context.not_found
    end
  end
end

hiera.yaml

---
version: 5
defaults:
  datadir: "data"
  data_hash: "yaml_data"
hierarchy:
  - name: "File Backend"
    lookup_key: "file_backend"
    options:
      directory: '/data/hiera'