Service group drivers forced_down flag utilization

Actual usage of the forced_down flag in case of usage of is_up() method. If
forced_down flag is set (i.e. have value True) than is_up unconditionally
return False - means service is down.

Partially-Implements: blueprint mark-host-down

Change-Id: Ia8ae49c5a38b217f19632a1ac40343ec9e608796

nova/servicegroup/api.py

@@ -88,6 +88,9 @@ class API(object):
         """Check if the given member is up."""
         # NOTE(johngarbutt) no logging in this method,
         # so this doesn't slow down the scheduler
+        if member.get('forced_down'):
+            return False
+
         return self._driver.is_up(member)
 
     def get_all(self, group_id):

nova/tests/unit/servicegroup/test_api.py

@@ -0,0 +1,71 @@
+# Copyright 2015 Intel Corp.
+#
+# 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 the base class for the servicegroup API
+"""
+import mock
+
+from nova import servicegroup
+from nova import test
+
+
+class ServiceGroupApiTestCase(test.NoDBTestCase):
+
+    def setUp(self):
+        super(ServiceGroupApiTestCase, self).setUp()
+        self.flags(servicegroup_driver='db')
+        self.servicegroup_api = servicegroup.API()
+        self.driver = self.servicegroup_api._driver
+
+    def test_join(self):
+        """"""
+        member = {'host': "fake-host", "topic": "compute"}
+        group = "group"
+
+        self.driver.join = mock.MagicMock(return_value=None)
+
+        result = self.servicegroup_api.join(member, group)
+        self.assertIsNone(result)
+        self.driver.join.assert_called_with(member, group, None)
+
+    def test_get_all(self):
+        result = "fake response"
+        group_id = 1
+
+        self.driver.get_all = mock.MagicMock(return_value=result)
+
+        members = self.servicegroup_api.get_all(group_id)
+        self.assertEqual(members, result)
+        self.driver.get_all.assert_called_with(group_id)
+
+    def test_service_is_up(self):
+        """"""
+        member = {"host": "fake-host",
+                  "topic": "compute",
+                  "forced_down": False}
+
+        for retval in (True, False):
+            driver = self.servicegroup_api._driver
+            driver.is_up = mock.MagicMock(return_value=retval)
+            result = self.servicegroup_api.service_is_up(member)
+
+            self.assertIs(result, retval)
+            driver.is_up.assert_called_with(member)
+
+        member["forced_down"] = True
+        for retval in (True, False):
+            driver = self.servicegroup_api._driver
+            result = self.servicegroup_api.service_is_up(member)
+            self.assertIs(result, False)