class { 'jails':
  defaults => {
    'interface'   => 'em0',
    'allow_mount' => true,
    'exec_start'  => '/bin/sh /etc/rc',
    'exec_stop'   => '/bin/sh /etc/rc.shutdown',
    'exec_clean'  => true,
    'mount_devfs' => true,
  }
}

jails::jail { 'webserver0':
  path          => '/jails/webserver0',
  ip4_addr      => '192.168.0.5',
  host_hostname => 'webserver0.example.org',
}