The Container Runtime Interface (CRI) was first introduced in Kubernetes v1.5 in 2016 and has been a crucial part of the system ever since. CRI lets you build Kubernetes in a container runtime agnostic manner. This talk goes into the details of how the CRI works and how you can work with the CRI to add new features with the example of KEP 4960: Container Stop Signals

This KEP added the StopSignal field to container lifecycle allowing users to set custom stop signals to their containers from the deployment spec. Previously it was only possible to configure this from the container image. As part of this KEP I had to learn how the CRI works, how we can develop and test changes to the CRI and different container runtimes locally and how you can build and test Kubernetes locally with these changes. This will be useful for anyone interested to start contributing to the kubelet and CRI areas of Kubernetes.

This talk will be my newly updated version of the talk I presented at KCD Taipei 2025