EKS interview question · Most asked
How do you upgrade an EKS cluster, and what are standard and extended support?
Summary
Upgrade one Kubernetes minor version at a time: check for removed APIs and add-on compatibility (EKS upgrade insights help), upgrade the control plane, then the EKS add-ons (VPC CNI, CoreDNS, kube-proxy, EBS CSI), then the nodes (new AMIs for managed node groups, Karpenter drift replacement, or Auto Mode handling it). EKS offers about 14 months of standard support per version, then an optional 12 months of extended support at a higher cluster fee.
Longer Answer
Control-plane upgrades cannot be rolled back, so test in a lower environment first. Node upgrades replace instances, so workloads need multiple replicas, PodDisruptionBudgets and graceful shutdown. Some teams use blue/green clusters for major changes, shifting traffic between an old and new cluster instead of upgrading in place.
Running versions into extended support raises costs, and once extended support ends EKS upgrades the cluster automatically, so treat upgrades as a regular cadence (a few times a year).
Key Points
- One minor version at a time.
- Check removed APIs and add-ons first.
- Control plane, add-ons, nodes.
- Standard ~14 months, extended +12 at higher cost.
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