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Karpenter now supports Amazon Application Recovery Controller zonal shift
Amazon EKS and Karpenter now support ARC zonal shift, allowing Kubernetes clusters to automatically move traffic and stop provisioning in impaired AWS Availability Zones during outages.
What: Amazon Elastic Kubernetes Service (EKS) integrates with Amazon Application Recovery Controller (ARC) zonal shift and zonal autoshift when using the open-source Karpenter project for node provisioning. This feature, released on May 12, 2026, allows Karpenter to automatically stop provisioning new compute capacity in an impaired Availability Zone (AZ) and redirect in-cluster network traffic away from it.
Why it matters: This integration enhances the resilience of multi-AZ Kubernetes deployments on AWS by providing an automated mechanism to react to AZ-level outages, reducing manual intervention and improving application availability during disruptions.
Takeaway: If you use Karpenter with Amazon EKS for highly available applications across multiple AZs, enable the ENABLE_ZONAL_SHIFT setting in your Karpenter configuration to automatically mitigate AZ impairments.
Deep dive
- Amazon EKS now supports Amazon Application Recovery Controller (ARC) zonal shift and zonal autoshift.
- This integration is specifically for EKS clusters using the open-source Karpenter project for compute provisioning.
- The feature, launched on May 12, 2026, aims to improve Kubernetes application availability during Availability Zone (AZ) impairments.
- When an ARC zonal shift is activated, Karpenter automatically stops provisioning new compute capacity in the impaired AZ.
- It also halts voluntary disruptions (like consolidation and drift) for nodes already in that AZ.
- Karpenter prevents voluntary disruptions in healthy zones if they would require scheduling pods into the impaired zone.
- Pods with strict scheduling requirements, such as volume affinities tied to the impaired AZ, will not trigger launch attempts.
- When the zonal shift expires or is canceled, Karpenter resumes normal operations.
- This functionality works with both manual zonal shifts and automated zonal autoshifts, which can include practice runs.
- No custom ARC resources are needed as Karpenter integrates directly with existing EKS cluster ARC resources.
- To enable, users need to set the ENABLE_ZONAL_SHIFT setting in their Karpenter configuration.
Decoder
- Amazon EKS (Elastic Kubernetes Service): A managed Kubernetes service that makes it easier to run Kubernetes on AWS without needing to install, operate, and maintain your own Kubernetes control plane.
- Karpenter: An open-source, high-performance Kubernetes node provisioning project that observes pending pods and launches optimally sized nodes to meet their requirements.
- Amazon Application Recovery Controller (ARC): An AWS service designed to help customers manage and coordinate recovery for their applications across AWS Regions and Availability Zones.
- Zonal shift: A feature of ARC that allows you to temporarily redirect network traffic away from an impaired Availability Zone without needing to redeploy or reconfigure your application.
- Zonal autoshift: An automated version of zonal shift where AWS can manage the traffic redirection on your behalf during an AZ impairment, including practice runs to verify functionality.
- Availability Zone (AZ): One or more discrete data centers with redundant power, networking, and connectivity in an AWS Region, isolated from failures in other AZs.
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