Provide context for castellan config validation

When starting the API we validate castellan's config. That bit might
require a context if you have use_barbican_key_manager = true. Adding a
context to keep config checking happy.

Change-Id: I63ea1d801339afb0bf861a0a480c408aaca2e25e
Closes-Bug: #1641897

sahara/main.py

@@ -13,6 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import contextlib
 import os
 
 from oslo_config import cfg
@@ -25,6 +26,7 @@ import stevedore
 from sahara.api import acl
 from sahara.common import config as common_config
 from sahara import config
+from sahara import context
 from sahara.i18n import _LI
 from sahara.plugins import base as plugins_base
 from sahara.service import api
@@ -77,7 +79,7 @@ def setup_common(possible_topdir, service_name):
 
     # Validate other configurations (that may produce logs) here
     cinder.validate_config()
-    castellan.validate_config()
+    validate_castellan_config()
 
     messaging.setup(service_name)
 
@@ -86,6 +88,11 @@ def setup_common(possible_topdir, service_name):
     LOG.info(_LI('Sahara {service} started').format(service=service_name))
 
 
+def validate_castellan_config():
+    with admin_context():
+        castellan.validate_config()
+
+
 def setup_sahara_api(mode):
     ops = _get_ops_driver(mode)
 
@@ -149,3 +156,13 @@ def launch_api_service(launcher, service):
     launcher.launch_service(service, workers=CONF.api_workers)
     service.start()
     launcher.wait()
+
+
+@contextlib.contextmanager
+def admin_context():
+    ctx = context.get_admin_context()
+    context.set_ctx(ctx)
+    try:
+        yield
+    finally:
+        context.set_ctx(None)

sahara/tests/unit/test_main.py

@@ -0,0 +1,60 @@
+# Copyright (c) 2016 SUSE LINUX Products GmbH
+#
+# 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.
+
+import mock
+import testtools
+
+from sahara import context
+from sahara import main
+
+
+def mock_validate_config():
+    return mock.patch(
+        'sahara.service.castellan.config.validate_config')
+
+
+class SomeException(Exception):
+    pass
+
+
+class ValidateCastellanTest(testtools.TestCase):
+
+    def test_castellan_validate_config_called(self):
+        with mock_validate_config() as validate_config:
+            main.validate_castellan_config()
+
+        validate_config.assert_called_once_with()
+
+    def test_context_present_when_calling_validate_config(self):
+
+        def check_context():
+            self.assertTrue(context.has_ctx())
+
+        with mock_validate_config() as validate_config:
+            validate_config.side_effect = check_context
+            main.validate_castellan_config()
+
+    def test_context_cleared(self):
+        with mock_validate_config():
+            main.validate_castellan_config()
+
+        self.assertFalse(context.has_ctx())
+
+    def test_context_cleared_in_case_of_exception(self):
+        with mock_validate_config() as validate_config:
+            validate_config.side_effect = SomeException
+            self.assertRaises(SomeException, main.validate_castellan_config)
+
+        self.assertFalse(context.has_ctx())