KubeCon + CloudNative North America 2022

The Node Resource Interface (NRI) was started as a subproject of containerd to provide OCI hook-like extensions as plugins which can perform extra actions outside the scope of CRI. This idea has since evolved into providing a common infrastructure for plugging extensions into CRI runtimes. Our proposed revision, which hopefully gets merged by the time of this presentation, turns NRI into a common runtime agnostic extension interface for plugging custom container adjustment logic into runtimes. It defines NRI using a formal protobuf protocol description and implements it as a set of ttRPC services. This improves the efficiency of plugin-runtime communication and enables straightforward implementation of stateful plugins. Our additions also expand the original scope of NRI, by allowing plugins to hook into virtually any of the pod and container life-cycle events and adjust a carefully chosen subset of container parameters. Integration to both containerd and CRI-O is available as experimental features. In this talk we'll take a closer look at how NRI and the plugins fit into runtimes, then cover some common and novel use cases, and example plugins for OCI hook injection and custom resource assignment.