add ssl support for redis with sentinel (#1327)

* add tls support for redis when using sentinel+redis

* fix non ssl case

flower/utils/broker.py

@@ -159,11 +159,12 @@ class RedisSentinel(RedisBase):
     def __init__(self, broker_url, *args, **kwargs):
         super().__init__(broker_url, *args, **kwargs)
         broker_options = kwargs.get('broker_options', {})
+        broker_use_ssl = kwargs.get('broker_use_ssl', None)
         self.host = self.host or 'localhost'
         self.port = self.port or 26379
         self.vhost = self._prepare_virtual_host(self.vhost)
         self.master_name = self._prepare_master_name(broker_options)
-        self.redis = self._get_redis_client(broker_options)
+        self.redis = self._get_redis_client(broker_options, broker_use_ssl)
 
     def _prepare_virtual_host(self, vhost):
         if not isinstance(vhost, numbers.Integral):
@@ -184,11 +185,14 @@ def _prepare_master_name(self, broker_options):
             raise ValueError('master_name is required for Sentinel broker') from exc
         return master_name
 
-    def _get_redis_client(self, broker_options):
+    def _get_redis_client(self, broker_options, broker_use_ssl):
         connection_kwargs = {
             'password': self.password,
             'sentinel_kwargs': broker_options.get('sentinel_kwargs')
         }
+        if isinstance(broker_use_ssl, dict):
+            connection_kwargs['ssl'] = True
+            connection_kwargs.update(broker_use_ssl)
         # get all sentinel hosts from Celery App config and use them to initialize Sentinel
         sentinel = redis.sentinel.Sentinel(
             [(self.host, self.port)], **connection_kwargs)