Generate /etc/hosts via usual host class, do not define a custom one

manifests/vagrant.pp

-node default {
-  class {'hosts':
-    hosts => {
-      'localhost' => '127.0.0.1',
-      "${hostname}" => '127.0.0.1',
-      'www.adblockplus.org' => '10.8.0.97',
-      'monitoring.adblockplus.org' => '10.8.0.98',
-      'server_1.adblockplus.org' => '10.8.0.105',
-      'server_3.adblockplus.org' => '10.8.0.99',
-      'server_4.adblockplus.org' => '10.8.0.98',
-      'server_5.adblockplus.org' => '10.8.0.100',
-      'server_6.adblockplus.org' => '10.8.0.101',
-      'server_7.adblockplus.org' => '10.8.0.102',
-      'server_8.adblockplus.org' => '10.8.0.103',
-      'server_9.adblockplus.org' => '10.8.0.104'
-    }
+define hostentry (
+  $host = $title['host'],
+  $ip = $title['ip']
+) {
+  host {$host:
+    ensure => present,
+    ip => $ip,
+    name => $host
   }
 }
+
+node default {
+
+  $hosts = [
+    {host => 'localhost', ip => '127.0.0.1'},
+    {host => $hostname, ip => '127.0.0.1'},
+    {host => 'www.adblockplus.org', ip => '10.8.0.97'},
+    {host => 'monitoring.adblockplus.org', ip => '10.8.0.98'},
+    {host => 'server_1.adblockplus.org', ip => '10.8.0.105'},
+    {host => 'server_3.adblockplus.org', ip => '10.8.0.99'},
+    {host => 'server_4.adblockplus.org', ip => '10.8.0.98'},
+    {host => 'server_5.adblockplus.org', ip => '10.8.0.100'},
+    {host => 'server_6.adblockplus.org', ip => '10.8.0.101'},
+    {host => 'server_7.adblockplus.org', ip => '10.8.0.102'},
+    {host => 'server_8.adblockplus.org', ip => '10.8.0.103'},
+    {host => 'server_9.adblockplus.org', ip => '10.8.0.104'}
+  ]
+
+  hostentry { $hosts: }
+}