This shit doesn't work

common.yaml

---
classes:
  - puppet
puppet::servername:    'hq-ext-puppet.sbgnet.com'
puppet::repository:    'puppetlabs'
puppet::environment:   'dmz'
puppet::environments:
    - 'dmz'

init.pp

class puppet(
  $servername,
  $server = $puppet::params::server,
  $environment = $puppet::params::environment,
  $environments = $puppet::params::environments,
  $daemon = $puppet::params::daemon,
  $repository = $puppet::params::repository,
) inherits puppet::params {

  if ( $servername == '' ) {
    fail('Must set servername => puppetmaster.example.com')
  }
  ...
}

node.pp

node 'puppetmaster' {
  hiera_include('classes')
}