file resource purge.

gistfile1.pp

define mytype {                                                                                                                                                                     

  # resource type that I don't want file to purge:
  # vhost { $name: ... }

  file { "/tmp/www/${name}":
  }
}

file { '/tmp/www':
  ensure => directory,
  purge => true,
}

# puppet won't touch the file /tmp/www/site_a or /tmp/www/site_b
mytype { 'site_a':
}

mytype { 'site_b':
}