The bill arrived on a Tuesday, up 38% on last month, and finance wanted to know why by Friday. The attachment was 2,400 lines of m5.2xlarge , persistent-disk-ssd , network-inter-region-egress . Nothing that mapped to a namespace, a team, or anything anyone in the room recognised.

If you run Kubernetes in production you've had this week, or you will. And the thing that makes it hard isn't the size of the number. It's that the cloud bill and the cluster are describing two entirely different systems in two entirely different languages, and the translation is your problem.

Right-sizing requests is where most of the advice lands, and it's not wrong, just downstream. You can't fix what you can't attribute. So before getting into tuning, it's worth looking at where the money actually goes, and why each category tends to quietly grow without anyone noticing.

Compute is the obvious one, usually 60 to 75% of the bill, and almost none of it is spent on the thing you'd expect.…