Amazon Elastic Kubernetes Service - Amazon Application Recovery Controller (ARC)
Using zonal shift for Amazon Elastic Kubernetes ServiceHow zonal shift works for Amazon Elastic Kubernetes Service

Amazon Elastic Kubernetes Service

Amazon EKS provides features that enable you to make your applications more resilient to events such as the degraded health or impairment of an Availability Zone (AZ). When running your workloads in an Amazon EKS cluster, you can further improve your application environment’s fault tolerance and application recovery using zonal shift or zonal autoshift.

Using zonal shift for Amazon Elastic Kubernetes Service

To enable zonal shift, use one of the following methods For more information, refer to Enable Amazon EKS Zonal Shift to avoid impaired Availability Zones.

Console
To enable zonal shift on a new Amazon EKS cluster (Console)

  1. Find the name and Region of the Amazon EKS cluster that you want to register with ARC.

  2. Open the Amazon EKS console at https://console.aws.amazon.com/eks/home#/clusters.

  3. Select your cluster.

  4. On the Cluster info page, select the Overview tab.

  5. Under the Zonal shift heading, select the Manage button.

  6. Select enable or disable for EKS Zonal Shift.

AWS CLI
To enable zonal shift on a new Amazon EKS cluster (AWS CLI)

  • Enter the following command:

    aws eks create-cluster --name my-eks-cluster --role-arn my-role-arn-to-create-cluster --resources-vpc-config subnetIds=string,string,securityGroupIds=string,string,endpointPublicAccess=boolean,endpointPrivateAccess=boolean,publicAccessCidrs=string,string --zonal-shift-config enabled=true
To enable zonal shift on an existing Amazon EKS cluster (AWS CLI)

  • Enter the following command:

    aws eks update-cluster-config --name my-eks-cluster --zonal-shift-config enabled=true

You can trigger a zonal shift for an Amazon EKS cluster, or you can allow AWS to do it for you by enabling zonal autoshift. Once your Amazon EKS cluster zonal shift enabled with ARC, you can trigger a zonal shift or enable zonal autoshift using the ARC Console, the AWS CLI, or the zonal shift and zonal autoshift APIs.

For more information on triggering a zonal shift, see Starting, updating, or canceling a zonal shift.

For more information on enabling Amazon EKS with zonal shift, refer to the Learn about ARC Zonal Shift in Amazon EKS topic in the Amazon Elastic Kubernetes Service User Guide.

How zonal shift works for Amazon Elastic Kubernetes Service

During an Amazon EKS zonal shift, the following will automatically take place:

  • All the nodes in the impacted AZ will be cordoned. This will prevent the Kubernetes Scheduler from scheduling new Pods onto the nodes in the unhealthy AZ.

  • If you’re using Managed Node Groups, Availability Zone rebalancing will be suspended, and your Auto Scaling Group (ASG) will be updated to ensure that new Amazon EKS Data Plane nodes are only launched in the healthy AZs.

  • The nodes in the unhealthy AZ will not be terminated and the Pods will not be evicted from these nodes. This is to ensure that when a zonal shift expires or gets cancelled, your traffic can be safely returned to the AZ which still has full capacity.

  • The EndpointSlice controller will find all the Pod endpoints in the impaired AZ and remove them from the relevant EndpointSlices. This will ensure that only Pod endpoints in healthy AZs are targeted to receive network traffic. When a zonal shift is cancelled or expires, the EndpointSlice controller will update the EndpointSlices to include the endpoints in the restored AZ.

For more information, refer to the AWS Containers blog.