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/init.pp

@@ -0,0 +1,15 @@
+# ExternalDNS BIND module - automatically configures master or slave
+class externaldns (
+  Stdlib::Fqdn $bind_master_hostname,
+  Array[Stdlib::Fqdn] $k8s_zones = [],
+  Array[Stdlib::Fqdn] $slave_servers = [],
+  String $externaldns_key_secret = '',
+  String $externaldns_key_algorithm = 'hmac-sha256',
+) {
+
+  if $trusted['certname'] == $bind_master_hostname {
+    include externaldns::master
+  } else {
+    include externaldns::slave
+  }
+}

modules/externaldns/manifests/master.pp

@@ -0,0 +1,45 @@
+# ExternalDNS BIND master server class
+class externaldns::master inherits externaldns {
+
+  include bind
+
+  # Query PuppetDB for slave server IP addresses
+  $slave_ips = $externaldns::slave_servers.map |$fqdn| {
+    puppetdb_query("inventory[facts.networking.ip] { certname = '${fqdn}' }")[0]['facts.networking.ip']
+  }.filter |$ip| { $ip != undef }
+
+  # Create TSIG key for ExternalDNS authentication
+  bind::key { 'externaldns-key':
+    algorithm => $externaldns::externaldns_key_algorithm,
+    secret    => $externaldns::externaldns_key_secret,
+  }
+
+  # Create ACL for slave servers
+  if !empty($slave_ips) {
+    bind::acl { 'dns-slaves':
+      addresses => $slave_ips,
+    }
+  }
+
+  # Create master zones for each Kubernetes domain
+  $externaldns::k8s_zones.each |$zone| {
+    bind::zone { $zone:
+      zone_type       => 'master',
+      dynamic         => true,
+      allow_updates   => ['key externaldns-key'],
+      allow_transfers => empty($slave_ips) ? {
+        true  => [],
+        false => ['dns-slaves'],
+      },
+      ns_notify       => !empty($slave_ips),
+      also_notify     => $slave_ips,
+      dnssec          => false,
+    }
+  }
+
+  # Create default view to include the zones
+  bind::view { 'externaldns':
+    recursion => false,
+    zones     => $externaldns::k8s_zones,
+  }
+}

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,
+  }
+}