HELLO 3 behavior breaks lettuce

[romange]

Based on private communication. Lettuce client stopped connecting to DF.

From reading this logic:
https://github.com/lettuce-io/lettuce-core/blob/5d3310d79967a580d172af7f6d9718ec9ed0325f/src/main/java/io/lettuce/core/RedisHandshake.java#L97

we should not return NOPROTO error upon "hello 3" command because the client code expects a ERR unknown command response.

[romange]

@alisaifee can you ptal? if you do not have the capacity, I will send a PR next week.

[alisaifee]

Ouch, that's unfortunate.

Initially when I looked at the expectation in the lettuce implementation it felt like a bit of a stretch to return the 'unknown command' family of errors. However, technically the current implementation of HELLO in df is a bit of a lie still since you could pass the authentication / set name arguments and the response would be (incorrectly) "OK".

Given that, what do you think of:

• accept only no arguments or protover=2 and return OK
• for all other arguments return `unknown command "HELLO", with args beginning with: ...."

[romange]

you mean - return the 12-item array and not "OK", right?
I agree, I think we should support "hello [2]". we can even support "hello 2 setname foo" since this functionality already exists.
For all other cases - return "unknown command..."

[alisaifee]

you mean - return the 12-item array and not "OK", right?

Apologies, my mind said HELLO RESPONSE but my fingers typed 'OK' ... not enough ☕, but yes.

[alisaifee]

Resolved in #129