Kubernetes Cloud Cost Optimization: Reducing EKS Bills with Karpenter

As Kubernetes clusters scale in production, cloud compute infrastructure quickly becomes one of the largest operational expenses for engineering organizations. Traditional Kubernetes Cluster Autoscaler (CA) relies on static AWS Auto Scaling Groups (ASGs), causing slow provisioning delays and inefficient instance sizing.

**Karpenter** is an open-source, high-performance node autoscaler designed specifically for Kubernetes on AWS.

**TL;DR:** Replace fixed ASGs with Karpenter just-in-time provisioning and AWS Spot Instances to lower Amazon EKS compute costs by up to 60% while speeding up pod scheduling latency.

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1. Karpenter NodePool & NodeClaim Architecture

Karpenter evaluates pending pods and provisions the optimal EC2 instance size automatically.

apiVersion: karpenter.sh/v1beta1
kind: NodePool
metadata:
  name: default-nodepool
spec:
  template:
    spec:
      requirements:
        - key: karpenter.sh/capacity-type
          operator: In
          values: ["spot", "on-demand"]
        - key: kubernetes.io/arch
          operator: In
          values: ["amd64", "arm64"] # Enables graviton cost savings
        - key: karpenter.k8s.aws/instance-category
          operator: In
          values: ["c", "m", "r"]
      nodeClassRef:
        apiVersion: karpenter.k8s.aws/v1beta1
        kind: EC2NodeClass
        name: default-nodeclass
  disruption:
    consolidationPolicy: WhenUnderutilized
    expireAfter: 720h # Rotate nodes every 30 days

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2. Infrastructure Cost & Scheduling Comparison