code: def wait_for_redis_to_start(redis_ip_address,
                              redis_port,
                              password=None,
                              num_retries=5):
      
      redis_client = redis.StrictRedis(
          host=redis_ip_address, port=redis_port, password=password)
      # Wait for the Redis server to start.
      counter = 0
      while counter < num_retries:
          try:
              # Run some random command and see if it worked.
              logger.info(
                  "Waiting for redis server at {}:{} to respond...".format(
                      redis_ip_address, redis_port))
              redis_client.client_list()
          except redis.ConnectionError:
              # Wait a little bit.
              time.sleep(1)
              logger.info("Failed to connect to the redis server, retrying.")
              counter += 1
          else:
              break
      if counter == num_retries:
          raise Exception("Unable to connect to Redis. If the Redis instance is "
                          "on a different machine, check that your firewall is "
                          "configured properly.")
docs: Wait for a Redis server to be available.
  
      This is accomplished by creating a Redis client and sending a random
      command to the server until the command gets through.
  
      Args:
          redis_ip_address (str): The IP address of the redis server.
          redis_port (int): The port of the redis server.
          password (str): The password of the redis server.
          num_retries (int): The number of times to try connecting with redis.
              The client will sleep for one second between attempts.
  
      Raises:
          Exception: An exception is raised if we could not connect with Redis.