config: Fix persist_config flag and function calls

The persist_config flag was setting the kwargs['config_persister'] to
the result of the function kcfg.save_changes and not the function
kcfg.save_changes itself.

Once this is fixed, the second problem was that the function was called
with an argument when it's defined without argument so an exception was
raised.

config/kube_config.py

@@ -336,7 +336,7 @@ def _refresh_azure_token(self, config):
         provider.value['access-token'] = token_response['accessToken']
         provider.value['expires-on'] = token_response['expiresOn']
         if self._config_persister:
-            self._config_persister(self._config.value)
+            self._config_persister()
 
     def _load_gcp_token(self, provider):
         if (('config' not in provider) or
@@ -357,7 +357,7 @@ def _refresh_gcp_token(self):
         provider.value['access-token'] = credentials.token
         provider.value['expiry'] = format_rfc3339(credentials.expiry)
         if self._config_persister:
-            self._config_persister(self._config.value)
+            self._config_persister()
 
     def _load_oid_token(self, provider):
         if 'config' not in provider:
@@ -398,7 +398,7 @@ def _load_oid_token(self, provider):
             self._refresh_oidc(provider)
 
             if self._config_persister:
-                self._config_persister(self._config.value)
+                self._config_persister()
 
         self.token = "Bearer %s" % provider['config']['id-token']
 
@@ -691,7 +691,7 @@ def _get_kube_config_loader_for_yaml_file(
 
     kcfg = KubeConfigMerger(filename)
     if persist_config and 'config_persister' not in kwargs:
-        kwargs['config_persister'] = kcfg.save_changes()
+        kwargs['config_persister'] = kcfg.save_changes
 
     if kcfg.config is None:
         raise ConfigException(

config/kube_config_test.py

@@ -33,6 +33,7 @@
                           ConfigNode, FileOrData, KubeConfigLoader,
                           KubeConfigMerger, _cleanup_temp_files,
                           _create_temp_file_with_content,
+                          _get_kube_config_loader_for_yaml_file,
                           list_kube_config_contexts, load_kube_config,
                           new_client_from_config)
 
@@ -1388,6 +1389,24 @@ def test_user_cmd_path_with_scope(self):
             "scopes can only be used when kubectl is using "
             "a gcp service account key")
 
+    def test__get_kube_config_loader_for_yaml_file_no_persist(self):
+        expected = FakeConfig(host=TEST_HOST,
+                              token=BEARER_TOKEN_FORMAT % TEST_DATA_BASE64)
+        config_file = self._create_temp_file(
+            yaml.safe_dump(self.TEST_KUBE_CONFIG))
+        actual = _get_kube_config_loader_for_yaml_file(config_file)
+        self.assertIsNone(actual._config_persister)
+
+    def test__get_kube_config_loader_for_yaml_file_persist(self):
+        expected = FakeConfig(host=TEST_HOST,
+                              token=BEARER_TOKEN_FORMAT % TEST_DATA_BASE64)
+        config_file = self._create_temp_file(
+            yaml.safe_dump(self.TEST_KUBE_CONFIG))
+        actual = _get_kube_config_loader_for_yaml_file(config_file,
+                                                       persist_config=True)
+        self.assertTrue(callable(actual._config_persister))
+        self.assertEquals(actual._config_persister.__name__, "save_changes")
+
 
 class TestKubernetesClientConfiguration(BaseTestCase):
     # Verifies properties of kubernetes.client.Configuration.