Kubernetes/Container Runtimes OCI

Overview

CRI Container Runtime Interface

Introduced in K8s in 2016, uses gRPC to expose the interface, can talk to different runtimes through the same API

containerd

Running in Kubernetes, execute on every node. You point kubelet to unix socket, that listens for gRPC/CRI calls.

systemctl start containerd
kubelet --containre-runtime=remote --runtime-request-timeout=15m \
        --containre-runtime-endpoint=unix:///run/containerd/containerd.sock

# Service unit
[Service]
Environment="KUBELET_EXTRA_ARGS=--containre-runtime=remote --runtime-request-timeout=15m 
--containre-runtime-endpoint=unix:///run/containerd/containerd.sock"

Worth to note:

• when you restart containerd daemon all your containers also get restarted

Resources

• Container runtimes part1 Read it first!, published in 2017
• Runtimes

CRI-O

Start it up, by pointing to a socket that listens for gRPC/CRI calls.

systemctl start crio
kubelet --container-runtime=remote --runtime-request-timeout=15m \
        --container-runtime-endpoint /var/run/crio/crio.sock ...

Worth to note:

• restarting the cri-o daemon won't cause container restart