Connecting to Google-hosted Redis with StackExchange not working with AuthString

Hello!

We are using StackExchange.Redis version 2.2.79 in a .NET Core 5.0 project, to connect to a Google Cloud Platform Redis instance (a.k.a Memorystore).

We are not using SSL for the connections, we just use what Google calls AuthString which is practically the password. We face issues when we are trying to connect to our instance using the library, while with redis-cli -a <password> the connection succeeds and we are able to see the contents.

The exception that we get in the code is:

StackExchange.Redis.RedisConnectionException: It was not possible to connect to the redis server(s). There was an authentication failure; check that passwords (or client certificates) are configured correctly.
   at StackExchange.Redis.ConnectionMultiplexer.ConnectImpl(ConfigurationOptions configuration, TextWriter log) in /_/src/StackExchange.Redis/ConnectionMultiplexer.cs:line 1194
   at StackExchange.Redis.ConnectionMultiplexer.Connect(ConfigurationOptions configuration, TextWriter log) in /_/src/StackExchange.Redis/ConnectionMultiplexer.cs:line 1061
   at StackExchange.Redis.ConnectionMultiplexer.Connect(String configuration, TextWriter log) in /_/src/StackExchange.Redis/ConnectionMultiplexer.cs:line 1036

For the connection through the library, we are using the following settings:

  ConfigurationOptions options = ConfigurationOptions.Parse("127.0.0.1:6379");
  options.Password = "auth-string-provided-from-gcp";
  options.AbortOnConnectFail = false;
  options.Ssl = false;
  _redisConnection = ConnectionMultiplexer.Connect(options);

P.S: If we disable authentication in GCP for our Redis instance, the connection through the library succeeds.

Start by reproducing the failure with StackExchange.Redis 2.2.79 using ConfigurationOptions.Parse, Password, Ssl=false, and ConnectionMultiplexer.Connect, then compare it with the successful redis-cli -a connection. Trace the authentication path from ConnectionMultiplexer.ConnectImpl and determine what is needed for Google Memorystore AuthString authentication; done means the configured connection authenticates successfully while authentication remains enabled.