Auto-scaling reacts too slow or flaps back and forth
Three calibrations: warming time, scale-out must be faster than scale-in, and pick the right metric. Default CPU target rarely works for modern apps.
Try this first
- 1Set scale-out aggressive, scale-in conservative. E.g. scale-out at 60 percent CPU for 2 minutes, scale-in at 30 percent for 15. Otherwise you flap.
- 2Pick a metric that reflects your real bottleneck. For web that's often ALB target-tracking on request count, not CPU.
- 3Set cooldown or warm pool. If instance startup is 3 minutes, a 1-minute evaluation interval is pointless.
- 4For predictable workloads (e-commerce, office-hour spike): predictive scaling based on pattern. Pre-fills for the spike.
- 5Load-test scaling with k6 or Locust. A config never tested will fall over during the first peak.
When to bring us in
If you breach SLA during peaks despite scaling, a short performance review is worth it. The fix usually sits in pool warmup or the app, not the auto-scaling config.
See also
- Everyone logs in with the AWS root accountRoot is for emergencies and billing. Day-to-day work belongs in IAM users or SSO.
- Every developer has AdministratorAccessAdministratorAccess everywhere is convenient now, painful later. Start with role-based policies.
- Everyone has individual IAM users with their own passwordIdentity Center (formerly AWS SSO) links to your IdP and issues temporary credentials per session.
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