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Amazon EKS Auto Mode

Amazon EKS Auto Mode is a variant of Amazon EKS where AWS manages the Kubernetes data plane (nodes, OS, default add-ons, cluster upgrades) in addition to the control plane — extending AWS's shared- responsibility line deeper into what used to be customer-operated infrastructure. Stub page — expand on future Auto Mode sources.

What AWS now manages (beyond standard EKS)

  • Node lifecycle — provisioning, scaling, termination, zone selection, instance-type choice within customer-configured pools. Integrates Karpenter-equivalent capacity planning.
  • Underlying OS — Bottlerocket is the default AMI. AWS publishes a new AMI on a regular cadence (typically weekly per Generali's account); nodes are terminated and replaced to apply it.
  • Default Amazon EKS add-ons — VPC CNI, CoreDNS, kube-proxy, CSI drivers, EBS drivers: AWS owns the version bump, customer does not need to schedule add-on upgrades.
  • Cluster upgrade cadence — the Kubernetes-version-upgrade activity that "usually takes a fair amount of time every quarter" is now AWS-managed.
  • Load balancers and storage configuration — per the AWS documentation cited by Generali: "EKS Auto Mode manages the underlying nodes, load balancers, and storage configuration automatically."

What customers still own

  • Node-pool policy — permitted instance types / sizes, zones, scale bounds (min/max), Spot vs On-Demand mix, taints/tolerations.
  • Workload concerns — Deployments, StatefulSets, HPAs, Services, Ingresses — everything above the node.
  • Custom add-ons — CNCF extensions beyond the default add-on set (Istio, Linkerd, Flux, ArgoCD, etc.) remain customer-managed.
  • Disruption controls — the load-bearing customer responsibility under Auto Mode. Because AWS actively terminates and replaces nodes on its upgrade cadence, the customer must configure:
  • Maintenance windows pinning when node replacement happens (off-peak hours).
  • Pod Disruption Budgets — K8s scheduler must never take down all replicas of a service simultaneously during drain.
  • Node Disruption Budgets bounding how many nodes can be replaced concurrently cluster-wide. Without these three, Auto Mode's managed upgrades become a self-inflicted DDoS on workloads. See patterns/disruption-budget-guarded-upgrades.

Position on the managed-data-plane spectrum

EKS Auto Mode sits alongside AWS's other managed-data-plane offerings: - AWS Lambda — fully serverless, no node concept at all; customer code only. - AWS Fargate — per-pod/per-task serverless containers; no node concept for the customer. - EKS Auto Mode — the customer still sees nodes (for scheduling, taints, resource limits, local ephemeral storage), but doesn't operate them. Nodes are a conceptual unit of resource budgeting, not an operational unit. - Standard EKS (non-Auto) — customer operates nodes directly (self-managed nodegroups, EKS-managed nodegroups with customer AMI control). - Self-hosted Kubernetes on EC2 — customer operates the control plane and data plane.

See concepts/managed-data-plane for the broader pattern.

Operational implications called out by Generali

  • The customer's role shifts from "monitoring the current services and making sure they stay compliant with upcoming Amazon EKS upgrades, an activity that usually takes a fair amount of time every quarter" to "focus on supporting their application teams."
  • The pattern rewards stateless-only discipline — because nodes are actively churned by the platform, any stateful pod on a node becomes a migration problem. Generali explicitly only runs stateless micro-services on their EKS Auto Mode cluster.
  • Pairs naturally with HPA — pod-level elasticity reacts to traffic while Auto Mode handles node-level provisioning/ right-sizing underneath.

Seen in

  • sources/2026-03-23-aws-generali-malaysia-eks-auto-mode — Generali Malaysia's adoption of EKS Auto Mode across their container-hosted digital + core-insurance applications. Canonical wiki reference for the managed-data-plane-at-K8s-layer pattern, the disruption-budget-guarded-upgrades contract, and the stateless-only compound discipline that Auto Mode rewards.
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