Stop calling get_all_types when service-type is None

If service_type=None makes it all the way here, there is really no need
to call get_all_types.

Story: 2003314
Change-Id: I04a4857a4ba131cc9aa05831ddc0c2d3d67903fd

openstack/config/cloud_region.py

@@ -229,6 +229,9 @@ class CloudRegion(object):
 
         If none of that works, it returns the value in ``default``.
         '''
+        if service_type is None:
+            return self.config.get(key)
+
         for st in self._service_type_manager.get_all_types(service_type):
             value = self.config.get(_make_key(key, st))
             if value is not None:

openstack/tests/unit/config/test_cloud_config.py

@@ -85,6 +85,20 @@ class TestCloudRegion(base.TestCase):
         cc2 = cloud_region.CloudRegion("test1", "region-al", {})
         self.assertNotEqual(cc1, cc2)
 
+    def test_get_config(self):
+        cc = cloud_region.CloudRegion("test1", "region-al", fake_services_dict)
+        self.assertIsNone(cc._get_config('nothing', None))
+        # This is what is happening behind the scenes in get_default_interface.
+        self.assertEqual(
+            fake_services_dict['interface'],
+            cc._get_config('interface', None))
+        # The same call as above, but from one step up the stack
+        self.assertEqual(
+            fake_services_dict['interface'],
+            cc.get_interface())
+        # Which finally is what is called to populate the below
+        self.assertEqual('public', self.cloud.default_interface)
+
     def test_verify(self):
         config_dict = copy.deepcopy(fake_config_dict)
         config_dict['cacert'] = None