🚀 EKS Cluster Upgrade on AWS (EKS) – Best Practices & Key Considerations 🚀

Upgrading your Kubernetes (K8s) cluster might seem intimidating at first, but with the right preparation and process, it can be a breeze. Whether you are managing your own cluster or using Amazon EKS, this guide has the essential best practices and key considerations to help you upgrade seamlessly.

🔧 Pre-Upgrade Checklist (prerequisites)

Before you dive into upgrading your EKS cluster, make sure you are prepared with these essentials:

Cordon Your Nodes
This is your first move—mark your nodes as unschedulable to prevent new pods from being scheduled during the upgrade. Typically, this process takes 1-2 hours, so be sure to inform your team.
Read the Release Notes
Don’t skip this step! Check out the release notes for any new features, bug fixes, or deprecated features (e.g., moving from K8S 1.30 to 1.31).
Test in Lower Environments
Kubernetes upgrades are irreversible, so make sure you’ve tested it thoroughly in a non-production environment. Allow a grace period of up to two weeks to monitor resources for any unusual behavior.
Ensure Version Consistency
Keep your control plane and nodes in sync—both should be running the same Kubernetes version. The kubelet should also match the control plane version for smooth compatibility.
Update the Cluster Auto-Scaler
If you’re using the Cluster Auto-Scaler, make sure it’s updated to the same version as the control plane and nodes for smooth scaling.
Check IP Availability
You’ll need at least 5 available IPs in the same subnet to make sure the upgrade runs smoothly. Don't overlook this!
Backup Your Data
Backup is always a must, especially for critical components like etcd and application data. Tools like eksctl or the AWS Management Console make it easy.

🌐 High Availability & Disaster Recovery

AWS EKS is designed to ensure high availability for your control plane across multiple availability zones. This built-in disaster recovery feature means that even if one zone fails, your cluster will continue to run smoothly.

🔄 The Upgrade Process for Managed K8s (EKS/AKS/GKE)

Here’s a breakdown of the upgrade process for your managed Kubernetes cluster:

Control Plane Upgrade
You can upgrade the control plane via AWS CLI, eksctl, or directly through the AWS Console. Don’t worry about scaling or disaster recovery—the AWS platform has you covered.
Data Plane Upgrade
Now it’s time to upgrade your nodes (or Fargate). Pay close attention to node groups and launch templates to ensure they’re aligned with the upgrade.
Update Your Add-ons
Don’t forget to update important add-ons like kubeproxy and VPC CNI. These are crucial to ensure that everything runs as expected after the upgrade.

⚡ Key Upgrade Considerations

Before hitting the “upgrade” button, here are a few things to keep in mind:

Node Upgrade Strategy
- AWS Node Groups with Launch Templates: AWS will manage the upgrade automatically, ensuring zero downtime by upgrading nodes one by one.
- Self-managed Nodes: You’ll need to cordon and upgrade nodes manually, one at a time, to prevent downtime.
- Hybrid Setups: You can also mix both approaches if you have a hybrid setup.
Managing Controllers
For tools like Helm, ArgoCD, or Prometheus, you don’t necessarily need to stop them during the upgrade. Just make sure you’ve tested everything in a lower environment first to minimize any risks when you go live.

💡 Pro Tip

Know your cluster inside and out. Before upgrading, ensure you understand your K8s components—add-ons, controllers, networking, and everything else. This knowledge will save you time and headaches during the upgrade.

🔍 Final Thought

Upgrading Kubernetes might feel complex, but with thorough preparation, testing, and phased upgrades, you can make the process smooth and stress-free. Backup, test, and upgrade wisely to ensure your production environment is rock-solid post-upgrade.

EKS Cluster upgrade