This is an example to install the newrelic-sysmond package on the Puppet Agent.

class system::newrelic-sysmond ($licensekey) {
  package { "newrelic-sysmond": ensure => installed, }

  exec { 'Insert newrelic license key':
    command => "nrsysmond-config --set license_key=$licensekey",
    require => Package['newrelic-sysmond'],
    creates => '/etc/newrelic/key_added',
  }

  exec { 'Restart newrelic system monitor':
    command => "/etc/init.d/newrelic-sysmond start",
    require => Exec['Insert newrelic license key'],
    creates => '/etc/newrelic/key_added',
  }

  exec { 'Create the key_added file':
    command => "echo key_added > /etc/newrelic/key_added",
    require => Exec['Restart newrelic system monitor'],
    creates => '/etc/newrelic/key_added',
  }
}

Done =)