What is EKS Automode?

Instead of predefining specific node groups, instance types, or scaling rules, EKS Automode automatically selects the best instance types and sizes based on the real-time resource requests of your workloads. It ensures that your cluster always has the right compute resources—no more guessing, tweaking, or overprovisioning.

Think of it as letting EKS handle the heavy lifting of node scaling so you can focus on running your workloads.

Why Was EKS Automode Introduced?

Traditionally, managing EKS node groups requires a lot of manual work:

• Picking instance types.
• Setting scaling rules.
• Managing node group configurations.
• Balancing between On-Demand and Spot Instances.

This can get messy, especially as your workloads change or grow unpredictably.

EKS Automode solves this by:

• Removing the need for static node group definitions.
• Automatically adjusting compute capacity based on pod needs.
• Optimizing for cost and availability in real time.

How Does EKS Automode Work?

When you enable Automode on your EKS cluster, here’s what happens:

1. Pod Scheduling Request
   When your workloads (pods) are deployed, they declare resource requests (CPU, memory, GPU, etc.).
2. Capacity Evaluation
   EKS Automode checks the current nodes. If none have room for the new pods, Automode steps in.
3. Dynamic Node Provisioning
   EKS automatically selects the most suitable EC2 instance types to satisfy the pod requirements—factoring in things like availability zones, price (including Spot and On-Demand), and hardware requirements.
4. Automatic Node Cleanup
   When nodes become idle (no pods scheduled), Automode scales them down to keep costs optimized.

EKS Automode vs. Karpenter: Are They the Same?

They are similar but not identical.

In short: EKS Automode is for teams who want “set it and forget it” and Karpenter is for teams who want more control and customization.

Benefits

• No node group management – AWS handles it behind the scenes.
• Optimized scaling – Matches resources to workload demand in real time.
• Cost-aware – Uses a smart mix of Spot and On-Demand instances.
• Automatic instance type selection – No need to predefine or guess.
• Simplified operations – Perfect for teams who want to offload infrastructure tuning.

Limitations

• Less customization – You can’t fine-tune node provisioning like you can with Karpenter.
• AWS-driven decisions – You have to trust AWS’s choices on instance types and scaling behavior.
• Works only on EKS – It’s tightly coupled with Amazon’s managed service, not portable like Karpenter.
• Newer feature – As of 2024, it’s still maturing and might not cover edge cases in complex environments.

When Should You Use EKS Automode?

EKS Automode is ideal if:

• You want to eliminate manual node group management.
• You have variable workloads with unpredictable scaling patterns.
• You prefer AWS to handle scaling logic for you.
• You want cost optimization without deep tuning.
• You’re running production workloads and want minimal maintenance overhead.

But if you need fine-grained control, like:

• Custom Spot allocation strategies.
• Special node constraints.
• Custom taints, labels, and topology control.

…then Karpenter might still be a better fit.

How to Enable EKS Automode

It’s simple to enable when creating a new EKS cluster via the AWS Console, CLI, or infrastructure-as-code tools like Terraform.

Example using AWS CLI:

aws eks create-cluster \
  --name my-cluster \
  --region us-east-1 \
  --kubernetes-version 1.28 \
  --resources-vpc-config subnetIds=subnet-12345678,subnet-87654321 \
  --auto-mode-enabled
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For existing clusters, you can enable Automode through cluster updates in the AWS Console or CLI.

Similar Concepts

References

• AWS Documentation
• AWS Blog
• Cluster Autoscaler on EKS