CNAME cannot coexist with other records on a node

octodns/zone.py

@@ -19,6 +19,10 @@ class DuplicateRecordException(Exception):
     pass
 
 
+class InvalidNodeException(Exception):
+    pass
+
+
 def _is_eligible(record):
     # Should this record be considered when computing changes
     # We ignore all top-level NS records
@@ -59,9 +63,17 @@ class Zone(object):
                 raise SubzoneRecordException('Record {} a managed sub-zone '
                                              'and not of type NS'
                                              .format(record.fqdn))
-        if record in self.records:
-            raise DuplicateRecordException('Duplicate record {}, type {}'
-                                           .format(record.fqdn, record._type))
+        for existing in self.records:
+            if record == existing:
+                raise DuplicateRecordException('Duplicate record {}, type {}'
+                                               .format(record.fqdn,
+                                                       record._type))
+            elif name == existing.name and (record._type == 'CNAME' or
+                                            existing._type == 'CNAME'):
+                raise InvalidNodeException('Invalid state, CNAME at {} '
+                                           'cannot coexist with other records'
+                                           .format(record.fqdn))
+
         self.records.add(record)
 
     def changes(self, desired, target):

tests/test_octodns_zone.py

@@ -8,7 +8,8 @@ from __future__ import absolute_import, division, print_function, \
 from unittest import TestCase
 
 from octodns.record import ARecord, AaaaRecord, Create, Delete, Record, Update
-from octodns.zone import DuplicateRecordException, SubzoneRecordException, Zone
+from octodns.zone import DuplicateRecordException, InvalidNodeException, \
+    SubzoneRecordException, Zone
 
 from helpers import SimpleProvider
 
@@ -205,3 +206,27 @@ class TestZone(TestCase):
 
         self.assertTrue(zone_missing.changes(zone_normal, provider))
         self.assertFalse(zone_missing.changes(zone_ignored, provider))
+
+    def test_cname_coexisting(self):
+        zone = Zone('unit.tests.', [])
+        a = Record.new(zone, 'www', {
+            'ttl': 60,
+            'type': 'A',
+            'value': '9.9.9.9',
+        })
+        cname = Record.new(zone, 'www', {
+            'ttl': 60,
+            'type': 'CNAME',
+            'value': 'foo.bar.com.',
+        })
+
+        # add cname to a
+        zone.add_record(a)
+        with self.assertRaises(InvalidNodeException):
+            zone.add_record(cname)
+
+        # add a to cname
+        zone = Zone('unit.tests.', [])
+        zone.add_record(cname)
+        with self.assertRaises(InvalidNodeException):
+            zone.add_record(a)