bundles/icinga2: use ip addresses for monitoring instead of hostnames

bundles/icinga2/items.py

@@ -340,11 +340,33 @@ for rnode in repo.nodes:
     if rnode.metadata.get('icinga_options/exclude_from_monitoring', False):
         continue
 
+    host_ips = repo.libs.tools.resolve_identifier(repo, rnode.name)
+    icinga_ips = {}
+
+    # XXX for the love of god, PLEASE remove this once DNS is no longer
+    # hosted at GCE
+    if rnode.in_group('gce'):
+        icinga_ips['ipv4'] = rnode.metadata.get('external_ipv4')
+    else:
+        for ip_type in ('ipv4', 'ipv6'):
+            for ip in sorted(host_ips[ip_type]):
+                if ip.is_private and not ip.is_link_local:
+                    icinga_ips[ip_type] = str(ip)
+                    break
+            else:
+                if host_ips[ip_type]:
+                    icinga_ips[ip_type] = sorted(host_ips[ip_type])[0]
+
+    if not icinga_ips:
+        raise ValueError(f'{rnode.name} requests monitoring, but has neither IPv4 nor IPv6 addresses!')
+
     files[f'/etc/icinga2/conf.d/hosts/{rnode.name}.conf'] = {
         'source': 'icinga2/hosts_template.conf',
         'content_type': 'mako',
         'context': {
             'rnode': rnode,
+            'address4': icinga_ips.get('ipv4', None),
+            'address6': icinga_ips.get('ipv6', None),
         },
         'owner': 'nagios',
         'group': 'nagios',