Add sentinel redis support

Redis client has an ability to connect to Redis server
using Sentinel[1] (especially important for Redis clusters),
but this ability was missing here.

Allow to pass 'sentinel' variable to Redis conf, extend
_make_client to use sentinel for that case.

[1] - https://github.com/andymccurdy/redis-py#sentinel-support

Change-Id: Ia8cc98e701435fd0231da3724f5d7108fc4f96f4

releasenotes/notes/add-sentinel-redis-support-9fd16e2a5dd5c0c9.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    Allow to use Sentinel for Redis connections. New variable *sentinel* can be
+    passed to Redis jobboard. It is None by default, Sentinel name should be passed
+    to enable this functionality.

taskflow/jobs/backends/impl_redis.py

@@ -29,6 +29,7 @@ from oslo_utils import strutils
 from oslo_utils import timeutils
 from oslo_utils import uuidutils
 from redis import exceptions as redis_exceptions
+from redis import sentinel
 import six
 from six.moves import range as compat_range
 
@@ -567,7 +568,19 @@ return cmsgpack.pack(result)
                     client_conf[key] = value_type_converter(conf[key])
                 else:
                     client_conf[key] = conf[key]
-        return ru.RedisClient(**client_conf)
+        if conf.get('sentinel') is not None:
+            sentinel_conf = {}
+            # sentinel do not have ssl kwargs
+            for key in client_conf:
+                if 'ssl' not in key:
+                    sentinel_conf[key] = client_conf[key]
+            s = sentinel.Sentinel([(sentinel_conf.pop('host'),
+                                    sentinel_conf.pop('port'))],
+                                  sentinel_kwargs=conf.get('sentinel_kwargs'),
+                                  **sentinel_conf)
+            return s.master_for(conf['sentinel'])
+        else:
+            return ru.RedisClient(**client_conf)
 
     def __init__(self, name, conf,
                  client=None, persistence=None):

taskflow/tests/unit/jobs/test_redis_job.py

@@ -15,6 +15,7 @@
 #    under the License.
 
 import time
+from unittest import mock
 
 from oslo_utils import uuidutils
 import six
@@ -102,3 +103,36 @@ class RedisJobboardTest(test.TestCase, base.BoardTestMixin):
     def setUp(self):
         super(RedisJobboardTest, self).setUp()
         self.client, self.board = self.create_board()
+
+    def test__make_client(self):
+        conf = {'host': '127.0.0.1',
+                'port': 6379,
+                'password': 'secret',
+                'namespace': 'test'
+                }
+        test_conf = {
+            'host': '127.0.0.1',
+            'port': 6379,
+            'password': 'secret',
+        }
+        with mock.patch('taskflow.utils.redis_utils.RedisClient') as mock_ru:
+            impl_redis.RedisJobBoard('test-board', conf)
+            mock_ru.assert_called_once_with(**test_conf)
+
+    def test__make_client_sentinel(self):
+        conf = {'host': '127.0.0.1',
+                'port': 26379,
+                'password': 'secret',
+                'namespace': 'test',
+                'sentinel': 'mymaster',
+                'sentinel_kwargs': {'password': 'senitelsecret'}}
+        with mock.patch('redis.sentinel.Sentinel') as mock_sentinel:
+            impl_redis.RedisJobBoard('test-board', conf)
+            test_conf = {
+                'password': 'secret',
+            }
+            mock_sentinel.assert_called_once_with(
+                [('127.0.0.1', 26379)],
+                sentinel_kwargs={'password': 'senitelsecret'},
+                **test_conf)
+            mock_sentinel().master_for.assert_called_once_with('mymaster')