Transactions are not well supported in Envoy Redis proxy scenario

[KirilNN]

Hello folks!

We are using SE.Redis client to connect to Envoy Redis proxy. We recently stumbled upon the following issue where our transactions started failing with an error. The minimum repro code is here:

var transaction = cache.CreateTransaction();
            
transaction.AddCondition(Condition.StringEqual("some_key", 1));
            
_ = transaction.StringIncrementAsync("some_key");
_ = transaction.StringSetAsync("some_key", + 1);
var result = await transaction.ExecuteAsync();

When the above is execute against Envoy Redis proxy we observe the following error

Unhandled exception. System.AggregateException: One or more errors occurred. (This operation has been disabled in the command-map and cannot be used: UNWATCH)

The problem comes from the fact that Envoy does not support the UNWATCH command, so maybe this can be replaced by DISCARD in the client, in order to make it compatible with Envoy? Will this be a viable option?

Any help is appreciated!

[dbarbosapn]

We'll try this one out envoyproxy/envoy#37620 and if it's viable, we can close this issue 😃

[dbarbosapn]

Quick update on this: After further investigation, DISCARD won't be a solution. Because: MULTI\r\nDISCARD\r\n does not get propagated to the underlying Redis cluster from Envoy, while WATCH does.

Meaning:
WATCH <key> <-- sent to Redis
MULTI <-- Not sent
DISCARD/EXEC <-- Not sent

will not clear the watch unless there is at least one operation inside the transaction.

[mgravell]

Ah yes, I can understand why they would do that; so: I think this is additional fuel for "this needs to be fixed in Envoy"