How I Cut AWS Compute Costs by 70% with a Multi-Arch EKS Cluster and Karpenter

Faced with slow Kubernetes scaling and rising AWS bills, I replaced the Cluster Autoscaler with Karpenter, built a multi-architecture EKS cluster (AMD64 + ARM64) using Terraform, and shifted 70% of workloads to Spot Instances. The result: 70% lower compute costs, sub-20-second scaling, and significantly better resource utilization in production.

After watching our monthly AWS bill climb steadily as our Kubernetes workloads grew, I knew we needed a smarter approach to node provisioning. Traditional cluster autoscaling was burning through our budget with over-provisioned nodes sitting idle, while still taking forever to scale up when I needed capacity.

I’d heard of Karpenter, but I hadn’t tried it. That incident pushed me to finally give it a shot. In this guide, I'll share how I built a production-ready, multi-architecture EKS cluster that cut our compute costs by 70% while making scaling nearly instantaneous.

• Switched from ...