KEDA 3.0 Scale-to-Zero: How We Cut Intermittent Kubernetes Workload Costs to Almost Nothing

KEDA 3.0 just landed, and the headline feature is the one I care about most as someone who watches a cloud bill: event-driven autoscaling now covers 80+ event sources (Kafka, RabbitMQ, and a long list more) with proper scale-to-zero. If you run workloads that sit idle most of the day and spike when work arrives, this is the difference between paying for capacity you use and paying for capacity that waits. I have been moving our intermittent workloads onto this pattern, so here is what scale-to-zero actually does to the bill, where it helps, and the sharp edges nobody mentions. The problem: HPA scales to one, not to zero Standard Horizontal Pod Autoscaler has a floor. minReplicas cannot be zero, so a workload that processes a queue twice a day still keeps at least one pod (and often the node under it) running 24/7. For a consumer that is busy 2 hours a day, you are paying for 22 hours of nothing. KEDA changes the shape of the question. Instead of "how many replicas does current CPU justify," it asks "are there events waiting." No events, zero pods. Events arrive, it scales from zero up to whatever the load needs. That floor of zero is the whole game for intermittent work. Where scale-to-zero actually pays off Not every workload benefits. The ones that do share a profile: bursty, event-triggered, and tolerant of a short cold start. In our environment the clear wins were: Queue consumers. A worker draining an SQS or RabbitMQ queue that fills a few times a day. Idle 80%+ of the time, now scales to zero between bursts. Kafka stream processors for low-volume topics that only see traffic during business hours. Scheduled batch jobs dressed up as long-running services because nobody wanted to re-architect them. Scale-to-zero gets most of the savings without the rewrite. Dev and staging consumers that had no reason to run overnight and did anyway. A rough sizing rule I use: if a workload is idle more than half the day and an extra few seconds of latency on the first event is