Generate the zone name following the spec of Google Cloud DNS

Zone name must begin with a letter, end with a letter or digit, and only contain lowercase letters, digits or dashes, and be 63 characters or less.
For instance, a reverse zone of IPv6 may violate the spec on the first character and the length of the zone name.

octodns/provider/googlecloud.py

@@ -127,9 +127,12 @@ class GoogleCloudProvider(BaseProvider):
             :type return: new google.cloud.dns.ManagedZone
         """
         # Zone name must begin with a letter, end with a letter or digit,
-        # and only contain lowercase letters, digits or dashes
+        # and only contain lowercase letters, digits or dashes,
+        # and be 63 characters or less
         zone_name = '{}-{}'.format(
-            dns_name[:-1].replace('.', '-'), uuid4().hex)
+            dns_name.replace('.', '-'), uuid4().hex)[:63]
+        if not zone_name[:1].isalpha():
+            zone_name = 'zone-{}'.format(zone_name[:58])
 
         gcloud_zone = self.gcloud_client.zone(
             name=zone_name,

tests/test_octodns_provider_googlecloud.py

@@ -427,3 +427,18 @@ class TestGoogleCloudProvider(TestCase):
 
         mock_zone.create.assert_called()
         provider.gcloud_client.zone.assert_called()
+
+    def test__create_zone_ip6_arpa(self):
+        def _create_dummy_zone(name, dns_name):
+            return DummyGoogleCloudZone(name=name, dns_name=dns_name)
+
+        provider = self._get_provider()
+
+        provider.gcloud_client = Mock()
+        provider.gcloud_client.zone = Mock(side_effect=_create_dummy_zone)
+
+        mock_zone = \
+            provider._create_gcloud_zone('0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa')
+
+        self.assertRegexpMatches(mock_zone.name, '^[a-z][a-z0-9-]*[a-z0-9]$')
+        self.assertEqual(len(mock_zone.name), 63)