EKS interview question · Most asked
EKS or ECS: how would you choose?
Summary
ECS is AWS's own container orchestrator: simpler, deeply integrated with AWS, no control-plane fee, and less to operate, especially with Fargate. EKS is standard Kubernetes: portable, with a huge ecosystem (Helm, operators, GitOps tools, service meshes), but more complex to run.
Longer Answer
Choose ECS when the team wants the simplest path to running containers on AWS, has no Kubernetes expertise, and does not need Kubernetes-specific tooling. Choose EKS when you need portability across clouds or on-premises, already have Kubernetes skills and tooling, rely on CNCF ecosystem components, or run complex platforms (many teams, custom controllers, GPU/ML scheduling). Cost differences come mostly from operations effort, not the EKS cluster fee.
Key Points
- ECS: simpler, AWS-native.
- EKS: portable, rich ecosystem, more complex.
- Team skills and ecosystem needs decide.
- Operational effort dominates cost.
Explanation
What interviewers look for
Matching the tool to team and requirements rather than defaulting to Kubernetes.
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?