feat: manage externaldns bind (#428)

- add module to manage externaldns bind for k8s
- add infra::dns::externaldns role
- add 198.18.19.20 as anycast for k8s external-dns service

Reviewed-on: #428

modules/externaldns/manifests/slave.pp

@@ -0,0 +1,36 @@
+# ExternalDNS BIND slave server class
+class externaldns::slave inherits externaldns {
+
+  include bind
+
+  # Query PuppetDB for master server IP address
+  $query = "inventory[facts.networking.ip] { certname = '${externaldns::bind_master_hostname}' }"
+  $master_ip = puppetdb_query($query)[0]['facts.networking.ip']
+
+  # Create TSIG key for zone transfers (same as master)
+  bind::key { 'externaldns-key':
+    algorithm => $externaldns::externaldns_key_algorithm,
+    secret    => $externaldns::externaldns_key_secret,
+  }
+
+  # Create ACL for master server
+  bind::acl { 'dns-master':
+    addresses => [$master_ip],
+  }
+
+  # Create slave zones for each Kubernetes domain
+  $externaldns::k8s_zones.each |$zone| {
+    bind::zone { $zone:
+      zone_type    => 'slave',
+      masters      => [$master_ip],
+      allow_notify => ['dns-master'],
+      ns_notify    => false,
+    }
+  }
+
+  # Create default view to include the zones
+  bind::view { 'externaldns':
+    recursion => false,
+    zones     => $externaldns::k8s_zones,
+  }
+}