Runaway Cloud Spend During Healthy Traffic

A cost-anomaly alert has fired: infrastructure spend is materially elevated versus the trailing baseline, following a recent deployment. Request latency, error rate, and throughput are all healthy right now and stay healthy throughout — there is no outage and no traffic spike here, only an economic problem. Three independent leftover misconfigurations are each contributing real, separate waste: the Autoscaler's target utilization was left at a conservative setting, the minimum replica count was raised during an unrelated past traffic-spike incident and never lowered back, and the idle-capacity policy never lets the fleet scale down during quiet periods. Five business invariants govern every decision here: (1) customer SLOs must remain within the authored bound at all times; (2) critical redundancy may not be removed below the stated safety floor, no matter how healthy traffic currently looks; (3) rightsizing may occur gradually, not instantly; (4) a temporary small latency increase is acceptable if it stays inside SLO; (5) cost reduction is a PRIMARY objective here, not a secondary bonus. The central trap: dropping the replica floor (or the idle-capacity drain policy) below the safety floor produces the cheapest infrastructure cost anywhere in this scenario while every customer-facing metric stays exactly as healthy as before. That apparent win is not real — it destroys redundancy headroom and creates a permanent, non-resetting historical record of how long the floor was breached that restoring it afterward does not erase. Decide how to right-size spend without ever trading away the redundancy this fleet exists to provide.

Difficulty

Senior Staff

Expected Time

~18 min

Category

Infrastructure & Capacity