From ca1646d394793f760185debab01578b47a7acafe Mon Sep 17 00:00:00 2001
From: Franziska Kunsmann <hi@kunsmann.eu>
Date: Fri, 16 Oct 2020 23:02:47 +0200
Subject: [PATCH] bundles/powerdns: add support for zone transfers

---
 bundles/powerdns/files/pdns.conf | 15 +++++++++
 bundles/powerdns/items.py        |  2 ++
 bundles/powerdns/metadata.py     | 55 ++++++++++++++++++++++++++++++++
 groups/features.py               |  2 ++
 nodes/gce/bind01.py              |  4 +++
 5 files changed, 78 insertions(+)

diff --git a/bundles/powerdns/files/pdns.conf b/bundles/powerdns/files/pdns.conf
index 4b64c72..dc67064 100644
--- a/bundles/powerdns/files/pdns.conf
+++ b/bundles/powerdns/files/pdns.conf
@@ -16,3 +16,18 @@ security-poll-suffix=
 server-id=${node.name}
 
 default-ttl=86400
+
+% if is_secondary:
+# Primary server: ${my_primary_server['node']}
+slave=yes
+superslave=yes
+allow-notify-from=${','.join(my_primary_server['ips'])}
+% else:
+allow-notify-from=
+% endif
+
+% if node.metadata['powerdns'].get('my_secondary_servers'):
+# This server is a primary server for the following nodes:
+# ${', '.join(node.metadata['powerdns']['my_secondary_servers'])}
+master=yes
+% endif
diff --git a/bundles/powerdns/items.py b/bundles/powerdns/items.py
index 414290e..02d7f0e 100644
--- a/bundles/powerdns/items.py
+++ b/bundles/powerdns/items.py
@@ -53,6 +53,8 @@ files = {
         'content_type': 'mako',
         'context': {
             'api_key': node.metadata['powerdns']['api_key'],
+            'is_secondary': node.metadata['powerdns'].get('is_secondary', False),
+            'my_primary_server': node.metadata['powerdns'].get('my_primary_server', {}),
         },
         'needs': {
             'pkg_apt:pdns-server',
diff --git a/bundles/powerdns/metadata.py b/bundles/powerdns/metadata.py
index 4e18293..3c28c97 100644
--- a/bundles/powerdns/metadata.py
+++ b/bundles/powerdns/metadata.py
@@ -1,3 +1,5 @@
+from bundlewrap.exceptions import NoSuchGroup
+
 defaults = {
     'apt': {
         'packages': {
@@ -23,3 +25,56 @@ defaults = {
         },
     },
 }
+
+
+@metadata_reactor
+def get_ips_of_secondary_nameservers(metadata):
+    # Secondary Nameservers can't be a primary nameserver at the same
+    # time. Return early if this is a secondary server.
+    if metadata.get('powerdns/is_secondary', False):
+        return {}
+
+    try:
+        nameservers = repo.nodes_in_group(metadata.get('powerdns/secondary_nameservers', ''))
+    except NoSuchGroup:
+        # This probably is no primary nameserver, either. Should be fine.
+        return {}
+
+    nodes = set()
+    for rnode in nameservers:
+        if rnode.name == node.name:
+            # We can't be primary and secondary at the same time
+            continue
+
+        nodes.add(rnode.name)
+
+    return {
+        'powerdns': {
+            'my_secondary_servers': nodes,
+        },
+    }
+
+
+@metadata_reactor
+def get_ips_of_primary_nameserver(metadata):
+    if not metadata.get('powerdns/is_secondary', False):
+        return {}
+
+    ips = set()
+    for rnode in repo.nodes:
+        if not node.has_bundle('powerdns'):
+            continue
+
+        if node.name in rnode.metadata.get('powerdns/my_secondary_servers', set()):
+            return {
+                'powerdns': {
+                    'my_primary_server': {
+                        'ips': {
+                            str(ip) for ip in repo.libs.tools.resolve_identifier(repo, rnode.name)
+                        },
+                        'node': rnode.name,
+                    },
+                },
+            }
+
+    return {}
diff --git a/groups/features.py b/groups/features.py
index 796369b..4605270 100644
--- a/groups/features.py
+++ b/groups/features.py
@@ -16,6 +16,8 @@ groups['dns'] = {
                 'bind': True,
                 'pgsql': True,
             },
+            # Overridden in node metadata for primary server
+            'is_secondary': True,
         },
     },
 }
diff --git a/nodes/gce/bind01.py b/nodes/gce/bind01.py
index e1f29ad..dc6ae76 100644
--- a/nodes/gce/bind01.py
+++ b/nodes/gce/bind01.py
@@ -31,6 +31,10 @@ nodes['gce.bind01'] = {
                 },
             },
         },
+        'powerdns': {
+            'is_secondary': False,
+            'secondary_nameservers': 'dns',
+        },
         'vm': {
             'cpu': 1,
             'ram': 1,