noop.pp

# set a global variable $::noop to true or false (without quotes) using an External Node Classifier
case "${::noop}" {
  'true','false': {
    ini_setting { "puppet.conf agent:noop=${::noop}":
      ensure  => present,
      path    => "${::settings::confdir}/puppet.conf",
      section => 'agent',
      setting => 'noop',
      value   => "${::noop}",
      noop    => false,
    }
  }
}