hiera_backend.pp

# replace hiera-file with a custom lookeup_key backend
function profiles::file::hiera_backend(
  String              $key,
  Hash                  $options,
  Puppet::LookupContext $context,
) {
  $contents = inline_template("<%= File.read('${options[path]}/${key}', mode: 'rb') {|f| f.read } if File.exists?('${options[path]}/${key}') %>")
  if $contents == '' or $contents == undef {
    $context.not_found
  }
  $contents
}