Have postfix listen only to loopback interface

gistfile1.pp

  # Keep postfix running
  service { "postfix":
    ensure => 'running',
    enable => 'true',
  }
  # Allow connections from localhost only
  augeas { "postfix_localhost_only":
    context => "/files/etc/postfix/main.cf/",
    changes => [
                "set inet_interfaces 127.0.0.1",
                ],
    notify => Service['postfix'],  # Restart postfix service if configuration changes
  }