I’ve been poking around recently with capturing Wi-Fi packet data and streaming it into Apache Kafka, from where I’m processing and analysing it. Kafka itself is rock-solid - because I’m using ☁️Confluent Cloud and someone else worries about provisioning it, scaling it, and keeping it running for me. But whilst Kafka works just great, my side of the setup—tshark running on a Raspberry Pi—is less than stable. For whatever reason it sometimes stalls and I have to restart the Raspberry Pi and restart the capture process.

ksqlDB 0.7 will add support for message keys as primitive data types beyond just STRING (which is all we’ve had to date). That means that Kafka messages are going to be much easier to work with, and require less wrangling to get into the form in which you need them. Take an example of a database table that you’ve ingested into a Kafka topic, and want to join to a stream of events. Previously you’d have had to take the Kafka topic into which the table had been ingested and run a ksqlDB processor to re-key the messages such that ksqlDB could join on them. Friends, I am here to tell you that this is no longer needed!

You can download the InfluxDB connector for Kafka Connect here. Documentation for it is here.

When a message from your source Kafka topic is written to InfluxDB the InfluxDB values are set thus:

This is based on using Confluent Cloud to provide your managed Kafka and Schema Registry. All that you run yourself is the Kafka Connect worker.

Optionally, you can use this Docker Compose to run the worker and a sample MySQL database.

Kafka Connect has as REST API through which all config should be done, including removing connectors that have been created. Sometimes though, you might have reason to want to manually do this—and since Kafka Connect running in distributed mode uses Kafka as its persistent data store, you can achieve this by manually writing to the topic yourself.