Everything You Ever Wanted to Know About CNIs (Container Network Interface) and ...
summary
Describes how Kubernetes networking actually works at the CNI level: kube-apiserver writes the Pod spec, kubelet asks containerd, containerd creates the pod network namespace and runs CNI binaries (via environment variables and stdin JSON) in sequence (loopback then a plugin like Flannel), the plugin configures eth0 and routes and returns a JSON result which containerd passes back to kubelet so the Pod becomes Running. Shows a wrapper script that pauses and logs CNI calls, warns that nodes can be marked Ready just because a CNI config JSON exists (even if networking is broken), gives the practical debugging tip of using nsenter into the pod network namespace to run tcpdump, and notes the CNI API is evolving toward gRPC.
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chapters (7)
- 0:00Introduction
- 4:33Installing and verifying CNI
- 12:52Creating a pod and running CNI
- 23:30Internal workings summary
- 25:34Debugging tips and tricks
- 28:43Future evolutions and summary
- 29:45Q&A
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