Building an IPC bus for Kubernetes sidecars: WAL, DLQ, and ring-buffer backpressure

If you put two sidecars in a pod and ask them to talk to each other over HTTP, sooner or later one of them crashes mid-request and you lose a message. If you do it enough times, you reinvent a message bus. This post is about the small in-pod message bus we ended up writing for k8s4claw, a Kubernetes