add docker env for integration testing

core/core/settings.py

@@ -207,7 +207,7 @@ CHANNEL_LAYERS = {
     'default': {
         'BACKEND': 'channels_redis.core.RedisChannelLayer',
         'CONFIG': {
-            'hosts': [('localhost', 6379)],
+            'hosts': [(os.getenv('REDIS_HOST', 'localhost'), 6379)],
         },
     }