Librdkafka is a C library implementation of the Apache Kafka protocol, containing both Producer and Consumer support. Most modern client libraries use librdkafka as the underlying implementation and are just a thin wrapper around it. You can read more about librdkafka here https://github.com/edenhill/librdkafka.
We use SASL SCRAM for authentication for our Apache Kafka cluster so it is important that librdkafka has the SSL and SASL SCRAM feature enabled to work with CloudKarafka.
You need to have OpenSSL / libcrypto installed for SSL and SASL SCRAM to work properly. Since Apple has deprecated their OpenSSL bundle, the easiest way is to install it via Homebrew
brew install openssl librdkafka
On Debian and Ubuntu, install librdkafka from the Confluent APT repositories, see instructions here and then install librdkafka:
apt-get install libssl-dev librdkafka-dev
Don't hesitate to contact us at support@cloudkarafka.com if you got any questions!