If you operate a Kafka cluster, hopefully you upgrade your brokers occasionally. Each release of Apache Kafka® includes detailed documentation that describes a tested procedure for doing a rolling upgrade of your cluster. Couldn’t be easier, right? Well, what if you have to do it with hundreds or thousands of brokers, such as you’d have to do if you were running Confluent Cloud? Today, Gwen Shapira shares some of the lessons she’s learned doing just that.