Under the Hood: Kubernetes QoS Classes

It is 3 a.m. and a node in your production cluster runs low on memory. When the dust settles, your payment service has been killed and restarted twice. The nightly batch job on the same node, the one nobody would miss for an hour, sailed through untouched. Nothing in the dashboards says why, and nobody made that choice on purpose. Except somebody did. Months earlier, someone wrote requests and limits into two manifests. The batch job got requests… Read More

Architecture: Docker

You ship a service that works perfectly on your laptop. It hits staging and dies immediately. The stack trace points at a shared library your machine had and the staging box did not. Someone on the team says the words every engineer has heard: "works on my machine." The old fix was a virtual machine. Package the whole operating system, ship the image, run it anywhere. It works, but you are shipping gigabytes of kernel and userland to so… Read More