{
  "id": 5470961,
  "title": "Can My AWS EKS Cluster Handle 100,000 Users? Load Testing + Autoscaling, Proven Live",
  "url": "https://urgent.news/2026/09/04/can-my-aws-eks-cluster-handle-100-000-users-load-testing-autoscaling",
  "topic": "tech",
  "section": "Tech",
  "published": "2026-09-04T02:08:58.000Z",
  "source": {
    "name": "Dev.to",
    "slug": "dev-to",
    "url": "https://dev.to/vijaya_bollu/can-my-aws-eks-cluster-handle-100000-users-load-testing-autoscaling-proven-live-274e"
  },
  "original_language": "en",
  "account": "The article details the results of load testing Amazon Web Services Elastic Kubernetes Service (EKS) clusters to determine if they can handle 100,000 users. The setup used a fixed 2-node EKS cluster running Google's Online Boutique with 11 services and no autoscaling. The new build introduced HorizontalPodAutoscaler (HPA) and metrics-server add-on, which were verified to be running before scaling. Karpenter was also introduced to provision new nodes when needed, eliminating the fixed node-group ceiling.\n\nDuring the load test, k6 was run in-cluster with 3,000 virtual users (VUs) rather than the full 100,000, to avoid exceeding the free-tier-eligible node ceiling. The HPA replicas climbed live as CPU/memory percentages exceeded target thresholds, while Karpenter watched for pending pods and provisioned new nodes as needed. Once the load test finished, Karpenter consolidated idle nodes back to the original 2 nodes.\n\nThe key takeaways from the article are:\n1. Verify metrics-server before trusting HPA, as an HPA without a metrics source doesn't scale and only appears as \"unknown\" targets.\n2. Karpenter removes the node-group ceiling, but EC2NodeClass constraints still need to match what the account is allowed to provision.\n3. Watching the load test end-to-end is crucial, as HPA config and node pool definition alone don't prove autoscaling works.\n4. Be honest about scale-down results; the test used 3,000 VUs rather than the full 100,000.\n\nThe article concludes by asking whether to use Karpenter or Cluster Autoscaler for EKS in 2026.",
  "summary": "Part 2 of a 4-part series — this article covers the repo at tag v2.0-load-testing-autoscaling. Part 1 (EKS deployment, tag v1.0-eks-deployment) is here . The Setup Last build: Google's Online Boutique running on a fixed 2-node AWS EKS cluster — 11 services, one Helm release, no autoscaling. The question this time: what actually happens under load? Not \"the YAML looks right\" — actually driven,…",
  "key_points": [
    "Verified metrics-server before trusting HPA for scaling",
    "Karpenter removes node-group ceiling but requires EC2NodeClass constraints",
    "Watching load test end-to-end crucial for autoscaling validation"
  ],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}