Add support for Vault Namespaces

Vault Namespaces [0] is a feature available in Vault Enterprise that
can be considered as a more advanced isolation feature on top of current
KV Mountpoint option in Castellan Vault plugin.

Passing a namespace in all request headers (including Auth) allows to organize
Vault-in-Vault style of isolation, with clients using the same simple URI path
but accessing separate sets of entities in Vault.

[0] https://www.vaultproject.io/docs/enterprise/namespaces

Change-Id: I627c20002bb2a0a1b346b57e824f87f856eca4c9

castellan/tests/unit/key_manager/test_vault_key_manager.py

@@ -0,0 +1,66 @@
+# Copyright (c) 2021 Mirantis Inc
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+"""
+Test cases for Vault key manager.
+"""
+import requests_mock
+
+from castellan.key_manager import vault_key_manager
+from castellan.tests.unit.key_manager import test_key_manager
+
+
+class VaultKeyManagerTestCase(test_key_manager.KeyManagerTestCase):
+
+    def _create_key_manager(self):
+        return vault_key_manager.VaultKeyManager(self.conf)
+
+    def test_auth_headers_root_token(self):
+        self.key_mgr._root_token_id = "spam"
+        expected_headers = {"X-Vault-Token": "spam"}
+        self.assertEqual(expected_headers,
+                         self.key_mgr._build_auth_headers())
+
+    def test_auth_headers_root_token_with_namespace(self):
+        self.key_mgr._root_token_id = "spam"
+        self.key_mgr._namespace = "ham"
+        expected_headers = {"X-Vault-Token": "spam",
+                            "X-Vault-Namespace": "ham"}
+        self.assertEqual(expected_headers,
+                         self.key_mgr._build_auth_headers())
+
+    @requests_mock.Mocker()
+    def test_auth_headers_app_role(self, m):
+        self.key_mgr._approle_role_id = "spam"
+        self.key_mgr._approle_secret_id = "secret"
+        m.post(
+            "http://127.0.0.1:8200/v1/auth/approle/login",
+            json={"auth": {"client_token": "token", "lease_duration": 3600}}
+        )
+        expected_headers = {"X-Vault-Token": "token"}
+        self.assertEqual(expected_headers, self.key_mgr._build_auth_headers())
+
+    @requests_mock.Mocker()
+    def test_auth_headers_app_role_with_namespace(self, m):
+        self.key_mgr._approle_role_id = "spam"
+        self.key_mgr._approle_secret_id = "secret"
+        self.key_mgr._namespace = "ham"
+        m.post(
+            "http://127.0.0.1:8200/v1/auth/approle/login",
+            json={"auth": {"client_token": "token", "lease_duration": 3600}}
+        )
+        expected_headers = {"X-Vault-Token": "token",
+                            "X-Vault-Namespace": "ham"}
+        self.assertEqual(expected_headers, self.key_mgr._build_auth_headers())