Continuing with my basic learning of Apache Kafka, and after the introductory course, I've recently finished also the second course in the series, Kafka Connect Hands-on Learning. Where the first one introduced the basics of producers, consumers, workers, topics, etc., here we learn about Source Connectors (inputs), Sink Connectors (outputs), what is a Kafka Connect Cluster, how to write your own connectors and how to deploy them.
The course has practical examples: Reading real-time Tweets into Kafka topics using a source connector, transform data from Kafka into Elasticsearch via a sink connector, and writing a connector that hooks into GitHub. Oh, and how to use the REST API to manage the connectors and their configurations.
Short one (4 hours, which easily you can follow at 1.25x speed) but well explained, with clear diagrams and interesting examples.