hosts.pp

class hosts {
  host { $::fqdn:
    ensure       => 'present',
    host_aliases => [$::hostname, 'localhost'],
    ip           => '127.0.0.1',
  }

  @@host { "${::fqdn}_example":
    ensure       => 'present',
    name         => $::fqdn,
    host_aliases => [$::hostname],
    ip           => $::ipaddress,
    tag          => 'example',
  }
  Host <<| title != $::fqdn and tag == 'example' |>>
}