Add warnings and safety checks and documentation

The changes in the `redhat-default-zones` branch, when released, may cause
upgrade difficulties for Red Hat system administrators. Try to ease the
transition.

manifests/defaults.pp

@@ -12,6 +12,7 @@ class bind::defaults (
     $bind_service           = undef,
     $nsupdate_package       = undef,
     $managed_keys_directory = undef,
+    $default_zones_warning  = undef,
 ) {
     unless is_bool($supported) {
         fail('Please ensure that the dependencies of the bind module are installed and working correctly')

manifests/init.pp

@@ -1,13 +1,14 @@
 # ex: syntax=puppet si ts=4 sw=4 et
 
 class bind (
-    $forwarders      = '',
-    $dnssec          = true,
-    $version         = '',
-    $rndc            = undef,
-    $statistics_port = undef,
-    $auth_nxdomain   = false,
-    $include_local   = false,
+    $forwarders            = '',
+    $dnssec                = true,
+    $version               = '',
+    $rndc                  = undef,
+    $statistics_port       = undef,
+    $auth_nxdomain         = false,
+    $include_local         = false,
+    $include_default_zones = true,
 ) inherits bind::defaults {
 
     File {

manifests/zone.pp

@@ -22,14 +22,20 @@ define bind::zone (
     # where there is a zone, there is a server
     include bind
 
-    # Pull some platform defaults into the local scope
+    # Pull some platform defaults and `bind` class parameters into the local scope
     $cachedir = $::bind::defaults::cachedir
     $random_device = $::bind::defaults::random_device
     $bind_user = $::bind::defaults::bind_user
     $bind_group = $::bind::defaults::bind_group
+    $default_zones_warning = $::bind::defaults::default_zones_warning
+    $include_default_zones = $::bind::include_default_zones
 
     $_domain = pick($domain, $name)
 
+    if $include_default_zones and $default_zones_warning and member(['.', 'localhost', '127.in-addr.arpa', '0.in-addr.arpa', '255.in-addr.arpa'], $_domain) {
+        warning("The bind module will include a default definition for zone \"${_domain}\" starting in version 6.0.0. Please see https://github.com/inkblot/puppet-bind/blob/master/DEFAULT_ZONES.md for more information about how this will affect your configuration.")
+    }
+
     unless !($masters != '' and ! member(['slave', 'stub'], $zone_type)) {
         fail("masters may only be provided for bind::zone resources with zone_type 'slave' or 'stub'")
     }