Autoscaler crashes if it cannot connect to Redis

[willgraf]

Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/redis/connection.py", line 492, in connect
    sock = self._connect()
  File "/usr/local/lib/python3.6/site-packages/redis/connection.py", line 520, in _connect
    socket.SOCK_STREAM):
  File "/usr/local/lib/python3.6/socket.py", line 745, in getaddrinfo
    for res in _socket.getaddrinfo(host, port, family, type, proto, flags):
socket.gaierror: [Errno -2] Name does not resolve

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "scale.py", line 76, in <module>
    backoff=decouple.config('REDIS_INTERVAL', default=1, cast=int))
  File "/usr/src/app/autoscaler/redis.py", line 133, in __init__
    self._update_masters_and_slaves()
  File "/usr/src/app/autoscaler/redis.py", line 137, in _update_masters_and_slaves
    self._sentinel.sentinel_masters()
  File "/usr/local/lib/python3.6/site-packages/redis/client.py", line 1062, in sentinel_masters
    return self.execute_command('SENTINEL MASTERS')
  File "/usr/local/lib/python3.6/site-packages/redis/client.py", line 772, in execute_command
    connection = pool.get_connection(command_name, **options)
  File "/usr/local/lib/python3.6/site-packages/redis/connection.py", line 994, in get_connection
    connection.connect()
  File "/usr/local/lib/python3.6/site-packages/redis/connection.py", line 497, in connect
    raise ConnectionError(self._error_message(e))
redis.exceptions.ConnectionError: Error -2 connecting to redis:26379. Name does not resolve.

Probably the same root cause as vanvalenlab/kiosk-redis-janitor#17

[leekiaxnn]

look like your redis service can not connect. connecting to redis:26379. Name does not resolve. . make sure that your cluster have redis and its service