dns: Determine Livermore presence based on IP, not parameter

We know the three large IP address blocks that exist in Livermore, and we now
have an ip_in_cidr() function, so we are using that to tell if a system is in
Livermore.

This code will need updating only if the large network blocks in Livermore are
changed.

NEWS

 Unreleased
 
+    [dns] Changes Livermore detection to use the system's primary IP address, 
+    instead of using a manually-set parameter. (akkornel)
 
 release/004.053 (2015-07-28)
 

manifests/dns.pp

@@ -7,14 +7,24 @@
 # If you use a DNS cache, you can change base::dns::dns_cache in Hiera to true, 
 # and 127.0.0.1 will be set as the first nameserver.
 
-# For Livermore sites, change base::dns::livermore to true, and the Livermore
-# DNS server will be added above the standard DNS servers.  If dns_cache is 
-# also true, Livermore DNS will be second (right below 127.0.0.1).
+# If the system's primary interface's IP address is in a known Livermore
+# network, then the Livermore DNS will be added above the standard DNS servers.
+# If dns_cache is also true, the Livermore DNS server will be second (right
+# below 127.0.0.1).
 class base::dns(
   $no_resolv_conf = false,
   $dns_cache      = 'NONE',
-  $livermore      = false,
 ) {
+
+  # Check if we are in Livermore, based on IP address
+  if (   ip_in_cidr($::ipaddress, '204.63.224.0/21')
+      or ip_in_cidr($::ipaddress, '172.20.224.0/21')
+  ) {
+    $livermore = true
+  } else {
+    $livermore = false
+  }
+
   if !$no_resolv_conf {
     base::dns::resolv_conf { $::fqdn_lc:
       ensure    => present,