KubeCon + CloudNativeCon North America 2019

Building a custom controller or operator to manage your Kubernetes applications is becoming easier, with the help of libraries and tools such as controller-runtime and Kubebuilder. Putting together an initial working prototype is fairly straightforward, but devil is in the details.

This talk focuses on lessons learned while writing Kubernetes controllers for stateful workloads with the help of controller-runtime. It covers some of the "hard parts".

The operator lives in the past: how to deal with resources cache inconsistencies? Why does idempotency matter? What can you do when StatefulSets are not good enough for the orchestration you need? How to empower advanced users but still provide good defaults? What namespace(s) should the operator have access to? How to test that monster you ended up building? These are questions engineers at Elastic had to answer.