Although Debezium makes it easy to capture database changes and record them in Kafka, one of the more important decisions you have to make is how those change events will be serialized in Kafka. Every message in Kafka has a key and a value, and to Kafka these are opaque byte arrays. But when you set up Kafka Connect, you have to say how the Debezium event keys and values should be serialized to a binary form, and your consumers will also have to deserialize them back into a usable form.
Debezium event keys and values are both structured, so JSON is certainly a reasonable option — it’s flexible, ubiquitous, and language agnostic, but on the other hand it’s quite verbose. One alternative is Avro, which is also flexible and language agnostic, but also faster and results in smaller binary representations. Using Avro requires a bit more setup effort on your part and some additional software, but the advantages are often worth it.
Our Debezium Tutorial walks you step by step through using Debezium by installing, starting, and linking together all of the Docker containers running on a single host machine. Of course, you can use things like Docker Compose or your own scripts to make this easier, although that would just automating running all the containers on a single machine. What you really want is to run the containers on a cluster of machines. In this blog, we’ll run Debezium using a container cluster manager from Red Hat and Google called Kubernetes.
Kubernetes is a container (Docker/Rocket/Hyper.sh) cluster management tool. Like many other popular cluster management and compute resource scheduling platforms, Kubernetes' roots are in Google, who is no stranger to running containers at scale. They start, stop, and cluster 2 billion containers per week and they contributed a lot of the Linux kernel underpinnings that make containers possible. One of their famous papers talks about an internal cluster manager named Borg. With Kubernetes, Google got tired of everyone implementing their papers in Java so they decided to implement this one themselves :)
Kubernetes is written in Go-lang and is quickly becoming the de-facto API for scheduling, managing, and clustering containers at scale. This blog isn’t intended to be a primer on Kubernetes, so we recommend heading over to the Getting Started docs to learn more about Kubernetes.