scram-vendored feature

[sproberts92]

sasl2-sys now has a separate feature for SCRAM without krb5. We'd like to expose this as a feature so we can use it downstream in https://github.com/vectordotdev/vector.

See the issue in that project for more context.

Credit to @Ilmarii in that issue for figuring out what is actually needed here.

[Neustradamus]

Thanks a lot @sproberts92!

[benesch]

I don't think this works quite the way you think! SASL SCRAM authentication is enabled by the ssl or ssl-vendored features. The reason is that librdkafka actually has a built-in implementation of SASL SCRAM authentication, but it requires the base64 encoding routines from OpenSSL. So you need to enable SSL in order to get access to that built-in implementation.

librdkafka only uses libsasl2 for Kerberos authentication. That's why it's gated here under gssapi, rather than libsasl2.

tl;dr you probably just need to enable the ssl-vendored feature on Windows in Vector.

[sproberts92]

@benesch thank you for your insight! I did not realise that librdkafka contained its own implementation for SCRAM, but indeed I now see it in there when I look through confluentinc/librdkafka.

I'll close this for now and discuss with the others what we need back on our Vector issue.