kubelet-tracer

README

Kubelet Tracer

This is a fork of github.com/markusthoemmes/kubelet-tracer.

As the name suggests, kubelet-tracer is a little tool that analyzes the logs of the kubelet for a specific pod to be able to reason about what exactly is going on in the kubelet for that respective pod. The tool has a focus on the timing of the kubelet's actions to be able to potentially improve the kubelet's pod/container bringup time and to reason about performance gaps.

This tastes really good in conjunction with podspeed to reason about pod startup timing.

kind "integration"

Since my workflow is currently centered around kind, there's a few helpers here that make iterating on Kubernetes changes a breeze.

rekind.sh

This script builds a node image from a fresh Kubernetes source (located at ~/go/src/k8s.io/kubernetes) and deploys a kind cluster with it. The kind configuration in kind.yaml makes sure, that the newly built image is used and that the kubelet logging is configured accordingly (JSON logging and log level raised to the max). The script is idempotent (hence the "re" prefix).

analyze_kind.sh

This script takes the pod you want to analyze as an argument (in the form of $ns/$name) and then takes care of exporting the respective logs from kind, piping them into kubelet-tracer and cleaning up after itself.

Streaming

docker exec verbose-control-plane journalctl -u kubelet -n100000 -f -o cat | kubelet-tracer --stop-after-deletion --pod startup-test-ygpvpxrv