# Autoscaling Surprise Bills — Target Tracking + Budget Checklist (July 2026)

## Scaling policy hygiene

- [ ] Prefer **target tracking** over asymmetric step scale-out / scale-in thresholds
- [ ] Set **max capacity** (EC2 ASG / ECS service / App Auto Scaling) to a real cost ceiling
- [ ] Cooldown / stabilization window reviewed after last peak (not default forever)
- [ ] Scale on the metric that tracks **cost drivers** (CPU ≠ request volume for I/O-bound apps)

## Lambda / Spot extras

- [ ] Lambda reserved concurrency + tight timeout + DLQ on queue consumers
- [ ] Spot: diversification + On-Demand baseline; watch replacement storms in DesiredCapacity

## Budgets that act

- [ ] Budget at 80% forecast → alert
- [ ] Budget Action at 100–120% → IAM deny launch / freeze ASG max / custom Lambda
- [ ] Cost Anomaly Detection / FinOps Agent on the same account as the ASG

## Monday diagnostic

```bash
# Inspect DesiredCapacity history (console or CLI) vs request/CPU metrics
# Flag: DesiredCapacity elevated >3× longer than the traffic peak
```