Distinguish a bad --redis-password from any other Redis error (#11893)

python/ray/_private/services.py

@@ -608,6 +608,17 @@ def wait_for_redis_to_start(redis_ip_address, redis_port, password=None):
                 "Waiting for redis server at {}:{} to respond...".format(
                     redis_ip_address, redis_port))
             redis_client.client_list()
+        # If the Redis service is delayed getting set up for any reason, we may
+        # get a redis.ConnectionError: Error 111 connecting to host:port.
+        # Connection refused.
+        # Unfortunately, redis.ConnectionError is also the base class of
+        # redis.AuthenticationError. We *don't* want to obscure a
+        # redis.AuthenticationError, because that indicates the user provided a
+        # bad password. Thus a double except clause to ensure a
+        # redis.AuthenticationError isn't trapped here.
+        except redis.AuthenticationError as authEx:
+            raise RuntimeError("Unable to connect to Redis at {}:{}.".format(
+                redis_ip_address, redis_port)) from authEx
         except redis.ConnectionError:
             # Wait a little bit.
             time.sleep(delay)