Root CNAMEs are not allowed

octodns/record.py

@@ -400,6 +400,14 @@ class AliasRecord(_ValueMixin, Record):
 class CnameRecord(_ValueMixin, Record):
     _type = 'CNAME'
 
+    @classmethod
+    def validate(cls, name, data):
+        reasons = []
+        if name == '':
+            reasons.append('root CNAME not allowed')
+        reasons.extend(super(CnameRecord, cls).validate(name, data))
+        return reasons
+
     @classmethod
     def _validate_value(cls, value):
         reasons = []

tests/test_octodns_provider_route53.py

@@ -1260,8 +1260,10 @@ class TestRoute53Records(TestCase):
                            False)
         self.assertEquals(c, c)
         d = _Route53Record(None, Record.new(existing, '',
-                                            {'ttl': 42, 'type': 'CNAME',
-                                             'value': 'foo.bar.'}),
+                                            {'ttl': 42, 'type': 'MX',
+                                             'value': {
+                                                 'priority': 10,
+                                                 'value': 'foo.bar.'}}),
                            False)
         self.assertEquals(d, d)
 

tests/test_octodns_record.py

@@ -859,15 +859,24 @@ class TestRecordValidation(TestCase):
 
     def test_CNAME(self):
         # doesn't blow up
-        Record.new(self.zone, '', {
+        Record.new(self.zone, 'www', {
             'type': 'CNAME',
             'ttl': 600,
             'value': 'foo.bar.com.',
         })
 
-        # missing trailing .
+        # root cname is a no-no
         with self.assertRaises(ValidationError) as ctx:
             Record.new(self.zone, '', {
+                'type': 'CNAME',
+                'ttl': 600,
+                'value': 'foo.bar.com.',
+            })
+        self.assertEquals(['root CNAME not allowed'], ctx.exception.reasons)
+
+        # missing trailing .
+        with self.assertRaises(ValidationError) as ctx:
+            Record.new(self.zone, 'www', {
                 'type': 'CNAME',
                 'ttl': 600,
                 'value': 'foo.bar.com',