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
• References

Core Concepts

Control Plane

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

Node Groups

Type	Description
Managed	AWS manages provisioning, updates
Self-managed	You manage EC2 instances
Fargate	Serverless, per-pod compute

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

Command	Description
aws eks create-cluster	Create cluster
aws eks describe-cluster	Get cluster details
aws eks update-cluster-config	Update cluster settings
aws eks delete-cluster	Delete cluster
aws eks update-kubeconfig	Configure kubectl

Node Groups

Command	Description
aws eks create-nodegroup	Create node group
aws eks describe-nodegroup	Get node group details
aws eks update-nodegroup-config	Update node group
aws eks delete-nodegroup	Delete node group

Add-ons

Command	Description
aws eks create-addon	Install add-on
aws eks describe-addon	Get add-on details
aws eks update-addon	Update add-on
aws eks delete-addon	Remove add-on

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

References

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