eks

type: skill name: eks description: AWS EKS Kubernetes management for clusters, node groups, and workloads. Use when creating clusters, configuring IRSA, managing node groups, deploying applications, or integrating with AWS services. last_updated: "2026-01-07" doc_source: https://docs.aws.amazon.com/eks/latest/userguide/

AWS EKS

Amazon Elastic Kubernetes Service (EKS) runs Kubernetes without installing and operating your own control plane. EKS manages the control plane and integrates with AWS services.

Table of Contents

• Core Concepts
• Common Patterns
• CLI Reference
• Best Practices
• Troubleshooting
• Security Checks
• External Accessibility Probe
• References

Core Concepts

Control Plane

Managed by AWS. Runs Kubernetes API server, etcd, and controllers across multiple AZs.

Node Groups

IRSA (IAM Roles for Service Accounts)

Associates Kubernetes service accounts with IAM roles for fine-grained AWS permissions.

Add-ons

Operational software: CoreDNS, kube-proxy, VPC CNI, EBS CSI driver.

Common Patterns

Create a Cluster

AWS CLI:

# Create cluster role
aws iam create-role \
  --role-name eks-cluster-role \
  --assume-role-policy-document '{
    "Version": "2012-10-17",
    "Statement": [{
      "Effect": "Allow",
      "Principal": {"Service": "eks.amazonaws.com"},
      "Action": "sts:AssumeRole"
    }]
  }'

aws iam attach-role-policy \
  --role-name eks-cluster-role \
  --policy-arn arn:aws:iam::aws:policy/AmazonEKSClusterPolicy

# Create cluster
aws eks create-cluster \
  --name my-cluster \
  --role-arn arn:aws:iam::123456789012:role/eks-cluster-role \
  --resources-vpc-config subnetIds=subnet-12345678,subnet-87654321,securityGroupIds=sg-12345678

# Wait for cluster
aws eks wait cluster-active --name my-cluster

# Update kubeconfig
aws eks update-kubeconfig --name my-cluster --region us-east-1

eksctl (Recommended):

# Create cluster with managed node group
eksctl create cluster \
  --name my-cluster \
  --region us-east-1 \
  --version 1.29 \
  --nodegroup-name standard-workers \
  --node-type t3.medium \
  --nodes 3 \
  --nodes-min 1 \
  --nodes-max 5 \
  --managed

Add Managed Node Group

# Create node role
aws iam create-role \
  --role-name eks-node-role \
  --assume-role-policy-document '{
    "Version": "2012-10-17",
    "Statement": [{
      "Effect": "Allow",
      "Principal": {"Service": "ec2.amazonaws.com"},
      "Action": "sts:AssumeRole"
    }]
  }'

aws iam attach-role-policy --role-name eks-node-role --policy-arn arn:aws:iam::aws:policy/AmazonEKSWorkerNodePolicy
aws iam attach-role-policy --role-name eks-node-role --policy-arn arn:aws:iam::aws:policy/AmazonEC2ContainerRegistryReadOnly
aws iam attach-role-policy --role-name eks-node-role --policy-arn arn:aws:iam::aws:policy/AmazonEKS_CNI_Policy

# Create node group
aws eks create-nodegroup \
  --cluster-name my-cluster \
  --nodegroup-name standard-workers \
  --node-role arn:aws:iam::123456789012:role/eks-node-role \
  --subnets subnet-12345678 subnet-87654321 \
  --instance-types t3.medium \
  --scaling-config minSize=1,maxSize=5,desiredSize=3 \
  --ami-type AL2_x86_64

Configure IRSA

# Enable OIDC provider
eksctl utils associate-iam-oidc-provider \
  --cluster my-cluster \
  --approve

# Create IAM role for service account
eksctl create iamserviceaccount \
  --cluster my-cluster \
  --namespace default \
  --name my-app-sa \
  --attach-policy-arn arn:aws:iam::aws:policy/AmazonS3ReadOnlyAccess \
  --approve

Manual IRSA setup:

# Get OIDC issuer
OIDC_ISSUER=$(aws eks describe-cluster --name my-cluster --query "cluster.identity.oidc.issuer" --output text)
OIDC_ID=${OIDC_ISSUER##*/}

# Create trust policy
cat > trust-policy.json << EOF
{
  "Version": "2012-10-17",
  "Statement": [{
    "Effect": "Allow",
    "Principal": {
      "Federated": "arn:aws:iam::123456789012:oidc-provider/oidc.eks.us-east-1.amazonaws.com/id/${OIDC_ID}"
    },
    "Action": "sts:AssumeRoleWithWebIdentity",
    "Condition": {
      "StringEquals": {
        "oidc.eks.us-east-1.amazonaws.com/id/${OIDC_ID}:sub": "system:serviceaccount:default:my-app-sa",
        "oidc.eks.us-east-1.amazonaws.com/id/${OIDC_ID}:aud": "sts.amazonaws.com"
      }
    }
  }]
}
EOF

aws iam create-role --role-name my-app-role --assume-role-policy-document file://trust-policy.json

Kubernetes Service Account

apiVersion: v1
kind: ServiceAccount
metadata:
  name: my-app-sa
  namespace: default
  annotations:
    eks.amazonaws.com/role-arn: arn:aws:iam::123456789012:role/my-app-role

Install Add-ons

# CoreDNS
aws eks create-addon \
  --cluster-name my-cluster \
  --addon-name coredns \
  --addon-version v1.11.1-eksbuild.4

# VPC CNI
aws eks create-addon \
  --cluster-name my-cluster \
  --addon-name vpc-cni \
  --addon-version v1.16.0-eksbuild.1

# kube-proxy
aws eks create-addon \
  --cluster-name my-cluster \
  --addon-name kube-proxy \
  --addon-version v1.29.0-eksbuild.1

# EBS CSI Driver
aws eks create-addon \
  --cluster-name my-cluster \
  --addon-name aws-ebs-csi-driver \
  --addon-version v1.27.0-eksbuild.1 \
  --service-account-role-arn arn:aws:iam::123456789012:role/ebs-csi-role

Deploy Application

# deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  replicas: 3
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      serviceAccountName: my-app-sa
      containers:
      - name: app
        image: 123456789012.dkr.ecr.us-east-1.amazonaws.com/my-app:latest
        ports:
        - containerPort: 8080
        resources:
          requests:
            cpu: 100m
            memory: 128Mi
          limits:
            cpu: 500m
            memory: 512Mi
---
apiVersion: v1
kind: Service
metadata:
  name: my-app
  annotations:
    service.beta.kubernetes.io/aws-load-balancer-type: nlb
spec:
  type: LoadBalancer
  ports:
  - port: 80
    targetPort: 8080
  selector:
    app: my-app

CLI Reference

Cluster Management

Node Groups

Add-ons

Best Practices

Security

• Use IRSA for pod-level AWS permissions
• Enable cluster encryption with KMS
• Use private endpoint for API server
• Enable audit logging to CloudWatch
• Use security groups for pods
• Implement network policies

# Enable secrets encryption
aws eks create-cluster \
  --name my-cluster \
  --encryption-config '[{
    "provider": {"keyArn": "arn:aws:kms:us-east-1:123456789012:key/..."},
    "resources": ["secrets"]
  }]' \
  ...

High Availability

• Deploy across multiple AZs
• Use managed node groups
• Set pod disruption budgets
• Configure horizontal pod autoscaling

Cost Optimization

• Use Spot instances for non-critical workloads
• Right-size nodes and pods
• Use Fargate for variable workloads
• Implement cluster autoscaler
• Use Karpenter for efficient scaling

Troubleshooting

Cannot Connect to Cluster

# Verify kubeconfig
aws eks update-kubeconfig --name my-cluster --region us-east-1

# Check IAM identity
aws sts get-caller-identity

# Verify cluster status
aws eks describe-cluster --name my-cluster --query 'cluster.status'

Nodes Not Joining

Check:

• Node IAM role has required policies
• Security groups allow node-to-control-plane communication
• Nodes have network access to API server

# Check node status
kubectl get nodes

# Check aws-auth ConfigMap
kubectl describe configmap aws-auth -n kube-system

# Check node logs (SSH to node)
journalctl -u kubelet

Pod Cannot Access AWS Services

# Verify IRSA setup
kubectl describe sa my-app-sa

# Check pod environment
kubectl exec my-pod -- env | grep AWS

# Test credentials
kubectl exec my-pod -- aws sts get-caller-identity

DNS Issues

# Check CoreDNS pods
kubectl get pods -n kube-system -l k8s-app=kube-dns

# Test DNS resolution
kubectl run test --image=busybox:1.28 --rm -it -- nslookup kubernetes

# Check CoreDNS logs
kubectl logs -n kube-system -l k8s-app=kube-dns

Security Checks

Key security controls to validate for EKS clusters:

External Accessibility Probe

Use when the question is "is this EKS cluster API server publicly accessible?" Tests the Kubernetes API endpoint from outside.

Step 1 — Discover cluster endpoint and access configuration:

aws eks describe-cluster \
  --name {{cluster}} \
  --region {{region}} \
  --query 'cluster.{Endpoint:endpoint,PublicAccess:resourcesVpcConfig.endpointPublicAccess,PublicCIDRs:resourcesVpcConfig.publicAccessCidrs,Version:version}' \
  --output json

If endpointPublicAccess: false → API server is private only. Probe not applicable from outside VPC. If endpointPublicAccess: true → proceed to probe.

Step 2 — Probe the API server endpoint:

curl -sI --max-time 10 {{endpoint}}

Note: A 401 or 403 means the API server is on the public internet. The finding severity depends on the public CIDR restriction (0.0.0.0/0 is critical; restricted CIDRs may be acceptable).

Step 3 — TLS/SSL validation:

# Extract hostname from endpoint URL
testssl.sh {{endpoint_hostname}}

The EKS API server endpoint is in the format https://{{id}}.gr7.{{region}}.eks.amazonaws.com. Extract the hostname for testssl.sh.

Scoring: Public endpoint + 0.0.0.0/0 CIDR + curl confirms reachability → Score 5. Public endpoint with restricted CIDRs + confirmed from allowed IP → Score 4. CLI config only (no probe) → Score 3.

References

• EKS User Guide
• EKS API Reference
• EKS CLI Reference
• eksctl
• EKS Best Practices Guide