Container Runtime Interface (CRI)

The Container Runtime Interface (CRI) is an API for container runtimes to integrate with kubelet.

Stuff you wanna know:

1. Kubelets always use CRI (except for using the rktnetes integration). The old, pre-CRI Docker integration was removed in 1.7.
2. Prior to the existence of CRI, container runtimes (e.g., docker, rkt) were integrated with kubelet through implementing an internal, high-level interface in kubelet.

More stuff:

• CRI installation documentation — https://kubernetes.io/docs/setup/production-environment/container-runtimes/
• On Github — https://github.com/kubernetes/community/blob/master/contributors/devel/sig-node/container-runtime-interface.md