Transforming hash in Puppet

transform.pp

$data = [
  {
    "certname"   => "server1",
    "parameters" => {
      "port" => 1234,
      "job"  => "job1"
    }
  },
  {
    "certname"   => "server2",
    "parameters" => {
      "port" => 5678,
      "job"  => "job1"
    }
  },
  {
    "certname"   => "server3",
    "parameters" => {
      "port" => 987,
      "job"  => "job2"
    }
  }
]

$output = $data.reduce({}) |$memo, $entry| {
  # Group entries by job
  $job = $entry['parameters']['job']
  $address = "${$entry['certname']}:${$entry['parameters']['port']}"
  if $memo[$job] {
    # Have to merge into the old hash because values are immutable in Puppet
    $memo + { $job => $memo[$job] + [$address] }
  } else {
    $memo + { $job => [$address] }
  }
}.map |$job, $entries| {
  {
    'job'     => $job,
    'entries' => $entries
  }
}

notice($output)