class apt::preferences {

  $pref_contents = $custom_preferences ? {
    '' => $operatingsystem ? {
      'debian' => template("apt/${operatingsystem}/preferences_${codename}.erb"),
      'ubuntu' => template("apt/${operatingsystem}/preferences_${codename}.erb"),
    },
    default => $custom_preferences
  }

  file { '/etc/apt/preferences':
    ensure => present,
    alias => 'apt_config',
    # only update together
    content => $pref_contents,
    require => File["/etc/apt/sources.list"],
    owner => root, group => 0, mode => 0644;
  }

}