EKS interview question · Most asked
How do you reduce EKS costs?
Summary
Right-size pod requests, scale nodes with Karpenter (consolidation, many instance types), use Spot for tolerant workloads and Graviton (ARM) instances where images support them, buy Savings Plans for the steady baseline, cut NAT and cross-AZ data transfer (VPC endpoints, topology-aware routing), share load balancers, keep clusters on standard-support versions, and allocate costs per team.
Longer Answer
Hidden costs often surprise people: NAT gateway data processing for image pulls (use ECR VPC endpoints), cross-AZ traffic between chatty services, CloudWatch log ingestion, idle non-production clusters (scale them down at night), and many small clusters each paying the control-plane fee and add-on overhead. Split cost allocation data for EKS in AWS Cost and Usage Reports, or tools such as Kubecost/OpenCost, attribute spend to namespaces and teams.
Key Points
- Right-size requests; Karpenter consolidation.
- Spot, Graviton, Savings Plans.
- Cut NAT and cross-AZ transfer.
- Stay in standard support; allocate costs.
More most-asked EKS questions
- What is Amazon EKS, and what does AWS manage versus what do you manage?
- Compare the EKS compute options: managed node groups, self-managed nodes, Fargate, Karpenter and EKS Auto Mode.
- How does the Amazon VPC CNI work, and why do EKS clusters run out of IP addresses?
- IRSA or EKS Pod Identity: how do pods get AWS permissions?
- How do you expose services on EKS? Explain the AWS Load Balancer Controller.
- How do you upgrade an EKS cluster, and what are standard and extended support?
- Why is Karpenter popular on EKS, and how does it differ from the Cluster Autoscaler?
- How do you secure an EKS cluster end to end?