remove required idp-certificate-authority-data in kubeconfig for oidc toke refresh, kubernetes-client/python#493

fix pep8 style
add unit test

config/kube_config.py

@@ -255,22 +255,27 @@ class KubeConfigLoader(object):
         return self.token
 
     def _refresh_oidc(self, provider):
-        ca_cert = tempfile.NamedTemporaryFile(delete=True)
-
-        if PY3:
-            cert = base64.b64decode(
-                provider['config']['idp-certificate-authority-data']
-            ).decode('utf-8')
-        else:
-            cert = base64.b64decode(
-                provider['config']['idp-certificate-authority-data'] + "=="
-            )
-
-        with open(ca_cert.name, 'w') as fh:
-            fh.write(cert)
-
         config = Configuration()
-        config.ssl_ca_cert = ca_cert.name
+
+        if 'idp-certificate-authority-data' in provider['config']:
+            ca_cert = tempfile.NamedTemporaryFile(delete=True)
+
+            if PY3:
+                cert = base64.b64decode(
+                    provider['config']['idp-certificate-authority-data']
+                ).decode('utf-8')
+            else:
+                cert = base64.b64decode(
+                    provider['config']['idp-certificate-authority-data'] + "=="
+                )
+
+            with open(ca_cert.name, 'w') as fh:
+                fh.write(cert)
+
+            config.ssl_ca_cert = ca_cert.name
+
+        else:
+            config.verify_ssl = False
 
         client = ApiClient(configuration=config)
 
@@ -301,7 +306,7 @@ class KubeConfigLoader(object):
                 refresh_token=provider['config']['refresh-token'],
                 auth=(provider['config']['client-id'],
                       provider['config']['client-secret']),
-                verify=ca_cert.name
+                verify=config.ssl_ca_cert if config.verify_ssl else None
             )
         except oauthlib.oauth2.rfc6749.errors.InvalidClientIdError:
             return

config/kube_config_test.py

@@ -373,6 +373,13 @@ class TestKubeConfigLoader(BaseTestCase):
                     "user": "expired_oidc"
                 }
             },
+            {
+                "name": "expired_oidc_nocert",
+                "context": {
+                    "cluster": "default",
+                    "user": "expired_oidc_nocert"
+                }
+            },
             {
                 "name": "user_pass",
                 "context": {
@@ -519,6 +526,22 @@ class TestKubeConfigLoader(BaseTestCase):
                     }
                 }
             },
+            {
+                "name": "expired_oidc_nocert",
+                "user": {
+                    "auth-provider": {
+                        "name": "oidc",
+                        "config": {
+                            "client-id": "tectonic-kubectl",
+                            "client-secret": "FAKE_SECRET",
+                            "id-token": TEST_OIDC_EXPIRED_LOGIN,
+                            "idp-issuer-url": "https://example.org/identity",
+                            "refresh-token":
+                                "lucWJjEhlxZW01cXI3YmVlcYnpxNGhzk"
+                        }
+                    }
+                }
+            },
             {
                 "name": "user_pass",
                 "user": {
@@ -649,6 +672,32 @@ class TestKubeConfigLoader(BaseTestCase):
         self.assertTrue(loader._load_oid_token())
         self.assertEqual("Bearer abc123", loader.token)
 
+    @mock.patch('kubernetes.config.kube_config.OAuth2Session.refresh_token')
+    @mock.patch('kubernetes.config.kube_config.ApiClient.request')
+    def test_oidc_with_refresh_nocert(
+            self, mock_ApiClient, mock_OAuth2Session):
+        mock_response = mock.MagicMock()
+        type(mock_response).status = mock.PropertyMock(
+            return_value=200
+        )
+        type(mock_response).data = mock.PropertyMock(
+            return_value=json.dumps({
+                "token_endpoint": "https://example.org/identity/token"
+            })
+        )
+
+        mock_ApiClient.return_value = mock_response
+
+        mock_OAuth2Session.return_value = {"id_token": "abc123",
+                                           "refresh_token": "newtoken123"}
+
+        loader = KubeConfigLoader(
+            config_dict=self.TEST_KUBE_CONFIG,
+            active_context="expired_oidc_nocert",
+        )
+        self.assertTrue(loader._load_oid_token())
+        self.assertEqual("Bearer abc123", loader.token)
+
     def test_user_pass(self):
         expected = FakeConfig(host=TEST_HOST, token=TEST_BASIC_TOKEN)
         actual = FakeConfig()