Upgrading your Amazon EKS clusters doesn’t have to be stressful. This guide helps DevOps engineers and Kubernetes administrators maintain up-to-date, secure self-managed EKS environments. We’ll walk through the essential upgrade fundamentals, show you how to assess your cluster’s readiness with a pre-upgrade checklist, and provide a detailed process for upgrading both your control plane and worker nodes. Stay current with AWS EKS while minimizing downtime and avoiding common upgrade pitfalls.
Understanding EKS Upgrade Fundamentals
Why regular upgrades matter for security and performance
Skipping EKS upgrades is like ignoring your car’s maintenance schedule. Sure, it’ll run for a while, but you’re asking for trouble down the road.
Security is the obvious big one. Kubernetes regularly patches vulnerabilities that could leave your infrastructure exposed. Remember the CVE-2023-2727 vulnerability? It allowed attackers to bypass authentication in certain scenarios. Companies that delayed upgrades were sitting ducks.
But it’s not just about plugging security holes. Performance improvements come with every release. Kubernetes 1.26 brought significant scheduler enhancements that reduced pod startup latency by nearly 30% in high-scale environments. That’s real money when you’re running hundreds of services.
And here’s what nobody tells you: the longer you wait, the more painful the upgrade becomes. Try jumping three versions at once and watch your weekend disappear debugging compatibility issues.
Key components in an EKS cluster upgrade
Upgrading EKS isn’t a single operation. You’re dealing with multiple moving parts:
- Control Plane – This is AWS’s responsibility but requires your initiation
- Worker Nodes – Your AMIs need updating to match the control plane
- Add-ons – Components like CoreDNS, kube-proxy, and the CNI plugin
- Applications – Your workloads may need adjustments for API changes
The most common mistake? Upgrading the control plane and forgetting about the add-ons. They’re version-specific and can cause mysterious failures if mismatched.
Worker nodes are where most headaches happen. You’ll need to decide between:
| Upgrade Method | Pros | Cons |
|---|---|---|
| In-place upgrades | No new infrastructure needed | Potential downtime |
| Blue/green deployments | Zero downtime | More complex, higher cost |
AWS EKS versioning explained
EKS follows standard Kubernetes versioning with its own twist. The format is simple: 1.XX.Y where XX is the minor version and Y is the patch.
AWS typically supports four Kubernetes minor versions at any time. When version 1.28 comes out, support for 1.24 starts winding down. You get about 14 months of support for each minor version before it’s deprecated.
What most people miss: AWS doesn’t automatically apply patch updates. If a critical security fix comes out as 1.25.6, your 1.25.4 cluster won’t magically update. You still need to trigger that patch upgrade yourself.
And pay attention to the EKS-specific optimizations. AWS often backports critical fixes to older versions, meaning your 1.25 cluster might get security patches not available in vanilla Kubernetes 1.25.
Planning your upgrade timeline strategically
Random upgrades lead to random problems. Smart teams follow a rhythm:
- Start with a non-production environment 4-6 weeks before production
- Test core functionality and monitor for at least a week
- Schedule production upgrades during lower traffic periods
- Build automated testing for post-upgrade verification
The release cadence matters too. Kubernetes drops new minor versions roughly every 4 months. Most mature teams skip every other version to balance stability with staying current. Going from 1.24 → 1.26 → 1.28 gives you more breathing room than chasing every release.
Budget more time than you think you need. Even “smooth” upgrades can reveal subtle application issues days later when traffic patterns change.
Pre-Upgrade Assessment Checklist
A. Evaluating current cluster health and configuration
Upgrading your EKS cluster isn’t something you just dive into on a Monday morning after your second coffee. Before touching anything, you need to know what you’re working with.
Start by running a thorough health check:
kubectl get nodes
kubectl get pods --all-namespaces
Look for any nodes in NotReady state or pods stuck in CrashLoopBackOff. These are red flags you need to address before upgrading.
Next, check your current versions:
aws eks describe-cluster --name your-cluster-name --query "cluster.version"
kubectl version --short
The gap between your control plane and worker nodes matters. If you’re running nodes with Kubernetes 1.23 and planning to jump to 1.26, you might be in for a bumpy ride.
Also examine your custom configurations:
kubectl get configmap -n kube-system
Pay special attention to any admission controllers, webhooks, or custom API resources that might be version-sensitive.
B. Identifying compatibility issues with workloads
Your applications aren’t just along for the ride – they need to work after the upgrade too. Start by auditing your deployments for deprecated APIs:
kubectl get -o yaml deployment,statefulset,daemonset --all-namespaces > all_workloads.yaml
Then search this file for any API versions that will be removed in your target version. The Kubernetes deprecation guide is your best friend here.
Container images are another common issue. Some workloads might have hard dependencies on specific Kubernetes features. Check your images:
kubectl get pods --all-namespaces -o jsonpath="{.items[*].spec.containers[*].image}" | tr -s '[[:space:]]' '\n' | sort | uniq
Older sidecar containers for logging, monitoring, or service mesh implementations often break during upgrades. Update them first if possible.
C. Resource planning for smooth transitions
Upgrades aren’t free – they cost compute resources and time. Your cluster needs extra capacity to handle the transition without disrupting services.
For worker node upgrades, you’ll need:
- At least 10-15% extra capacity to handle pod migrations
- Sufficient IP addresses in your VPC subnets
- Enough CPU/memory to temporarily run duplicate workloads
Create a resource requirement table:
| Resource | Current Usage | Estimated Need During Upgrade | Gap |
|---|---|---|---|
| Nodes | 10 | 12 | +2 |
| vCPUs | 40 | 48 | +8 |
| Memory | 160GB | 192GB | +32GB |
| IP addresses | 50/100 | 65/100 | OK |
If you’re using spot instances, consider switching to on-demand for the upgrade process. Spot terminations during upgrades are a special kind of headache.
D. Creating backup and rollback strategies
Nobody plans to fail, but everybody should plan for failure. Before upgrading, you need solid backups and a clear rollback path.
Backup these critical components:
- etcd data (if using self-managed etcd)
- PersistentVolume data
- Kubernetes resource definitions
Run this to capture your cluster state:
kubectl get all --all-namespaces -o yaml > cluster_backup.yaml
For stateful applications, take snapshots of your volumes. If using EBS, create snapshots through the AWS console or CLI.
Your rollback strategy should include:
- Documented steps to revert to the previous control plane version
- A plan to restore worker nodes to the original AMI/version
- Recovery time objectives for different failure scenarios
Test your backup restoration process before proceeding. A backup you can’t restore is just wishful thinking.
E. Testing upgrade procedures in non-production environments
The upgrade process should never make its debut in production. Create a staging environment that mirrors your production setup as closely as possible.
Start with a clone of your cluster:
- Create a new EKS cluster with the same version as production
- Deploy the same addons and configurations
- Import a subset of your workloads (especially custom or critical ones)
Run through the entire upgrade process and document each step. Watch for:
- Failed pod scheduling
- Broken service connections
- Config map or secret access issues
- API compatibility problems
Time everything. How long did the control plane upgrade take? How about draining and upgrading each node group? These metrics help you plan your production maintenance window.
After testing, create a detailed runbook with commands, expected outputs, and troubleshooting steps. Include time estimates for each phase based on your testing.
Step-by-Step EKS Control Plane Upgrade Process
Using AWS Management Console for upgrades
Upgrading your EKS control plane through the AWS Console is probably the easiest approach if you’re not a CLI power user. Just head over to the EKS console, select your cluster, and hit the “Update” button.
But wait – before you click that button, take a screenshot of your current configuration. Trust me, you’ll thank yourself later if something goes sideways.
The console will show you all available versions to upgrade to. You can only move up one minor version at a time (like 1.22 to 1.23), so don’t expect to jump from 1.20 straight to 1.25 in one go.
Once you confirm the upgrade, AWS handles the heavy lifting behind the scenes. The beauty? Your applications keep running during this process since AWS maintains API server availability.
CLI-based upgrade commands and options
If you’re a command line fan (or need to automate upgrades), the AWS CLI is your friend. The basic command structure is straightforward:
aws eks update-cluster-version --name your-cluster-name --kubernetes-version 1.25
For those who need more control, add these useful flags:
aws eks update-cluster-version \
--name production-cluster \
--kubernetes-version 1.25 \
--client-request-token uniqueID123 \
--profile prod-account
The client-request-token is handy for tracking specific upgrade operations, especially when automating across multiple clusters.
You can also check your upgrade status anytime:
aws eks describe-update --name your-cluster-name --update-id your-update-id
Monitoring control plane health during transitions
During upgrades, keeping tabs on your control plane health isn’t just nice – it’s essential. The control plane metrics to watch include:
- API server response times
- etcd performance
- Request failure rates
- Control plane component health
Set up CloudWatch dashboards before you start the upgrade so you can spot problems early. A spike in API server latency or error rates is often the first warning sign of trouble.
Pro tip: Run a simple polling script checking the /healthz endpoint during the upgrade. Something like:
while true; do
date
kubectl get --raw='/healthz'
sleep 5
done
Troubleshooting common control plane upgrade issues
Upgrades sometimes hit snags. Here are the usual suspects and how to fix them:
Stuck in “Updating” state: If your cluster seems frozen in update mode for more than 30 minutes, check the update status with:
aws eks describe-update --name cluster-name --update-id update-id
Look for error messages in the output.
API connectivity issues: Sometimes right after an upgrade, API connections act flaky. This often resolves within 5-10 minutes as DNS propagates, but you might need to restart the kubectl proxy or reset your kubeconfig.
Version mismatch warnings: If you see warnings about version skew between your control plane and kubectl, update your local tools:
curl -LO "https://dl.k8s.io/release/v1.25.0/bin/linux/amd64/kubectl"
Remember: Most control plane issues are temporary. Wait 10-15 minutes before trying more aggressive troubleshooting.
Worker Node Group Upgrades
A. Choosing between rolling updates and blue/green deployments
Upgrading worker nodes is like remodeling your house while still living in it – tricky but totally doable with the right approach.
Rolling updates are your gradual renovation – replace one node at a time while keeping everything running. The cluster stays operational, and pods get rescheduled as you go. It’s cost-effective but takes longer and could cause capacity hiccups if you’re running close to the edge.
Blue/green deployments are more like building a new house before moving out of the old one. You create an entirely new node group alongside the existing one, then switch traffic over when ready. Zero downtime, instant rollback capabilities, but double the resources during transition.
Here’s a quick comparison:
| Approach | Pros | Cons |
|---|---|---|
| Rolling updates | Lower cost, simpler process | Longer completion time, temporary reduced capacity |
| Blue/green | Zero downtime, easy rollbacks | Higher cost, more complex orchestration |
Pick rolling updates when you’re budget-conscious and your workloads can handle some shifting around. Go with blue/green when downtime is forbidden and you need that safety net of instant rollbacks.
B. Automating node group upgrades with AWS tools
Nobody wants to manually upgrade dozens of nodes at 2 AM. That’s where automation saves your sanity.
AWS provides several tools to make this process painless:
eksctl is your Swiss Army knife for EKS operations. With a simple command like eksctl upgrade nodegroup, you can kick off a smooth rolling update.
eksctl upgrade nodegroup --cluster=my-cluster --name=workers-1.22 --kubernetes-version=1.23
AWS Node Termination Handler watches for EC2 lifecycle events and gracefully drains nodes before termination, preventing those nasty disruptions when instances get recycled.
For the infrastructure-as-code crowd, AWS CloudFormation and Terraform let you declare your desired node group state, then automatically handle the transition from old to new.
The managed node groups feature is perhaps the biggest time-saver – AWS automatically replaces nodes that fail health checks and handles Kubernetes version compatibility for you.
C. Managing custom AMIs in your upgrade strategy
Stock AMIs are convenient but sometimes you need something tailored to your specific needs – that’s where custom AMIs come in.
Building and maintaining custom AMIs adds complexity but gives you control over pre-installed packages, security hardening, and performance tuning. Using Packer with your CI/CD pipeline makes this process repeatable and version-controlled.
The real trick is keeping these custom images current with Kubernetes versions. Each K8s release requires specific container runtime versions and kernel modules. Falling behind can leave you stuck when it’s time to upgrade.
Create a testing schedule for new AMIs. Before promoting to production, verify compatibility with your workloads in a staging environment.
Consider a hybrid approach – use Amazon’s optimized AMIs as your base, then apply your customizations through bootstrap scripts or configuration management tools like Ansible. This gives you the best of both worlds – AWS-maintained Kubernetes compatibility plus your special sauce.
D. Handling stateful workloads during node refreshes
Stateless applications couldn’t care less which node they run on, but stateful workloads get attached to their persistent storage.
PersistentVolumes and StorageClasses are your friends here. Configure your stateful applications to use EBS volumes that detach from the old node and reattach to the new one.
Still, storage reattachment takes time, so plan for temporary unavailability. Set appropriate Pod Disruption Budgets (PDBs) to ensure only one replica of your stateful service goes down at a time:
apiVersion: policy/v1
kind: PodDisruptionBudget
metadata:
name: db-pdb
spec:
maxUnavailable: 1
selector:
matchLabels:
app: database
For databases and other critical stateful services, consider using operators like the AWS Controllers for Kubernetes (ACK) that understand the application lifecycle and can orchestrate proper shutdown and startup sequences.
Drain nodes carefully with kubectl drain --ignore-daemonsets --delete-emptydir-data to give pods time for graceful termination.
Post-Upgrade Validation and Optimization
A. Verifying cluster functionality and performance
You’ve completed the upgrade. Great! But now comes the crucial part – making sure everything actually works. Start with basic health checks:
kubectl get nodes
kubectl get pods --all-namespaces
Look for any nodes not showing “Ready” or pods stuck in “Pending” or “CrashLoopBackOff” states. Run a performance comparison to see if your upgrade helped or hurt:
kubectl top nodes
kubectl top pods --all-namespaces
Compare these metrics with your pre-upgrade baseline. Notice any spikes? That’s a red flag worth investigating.
B. Testing critical workloads and applications
Your infrastructure might look fine, but what about your actual apps? Run through your test suite to verify functionality:
- Deploy a canary version of your application
- Test core functionality paths
- Monitor error rates in your logs and metrics
- Check integration points with external services
Don’t have a test suite? Create one now. Seriously. You’ll thank yourself during the next upgrade.
C. Implementing new version-specific features
Each EKS version brings new goodies. Don’t just upgrade and call it a day – take advantage of them!
For example, newer EKS versions support:
- Enhanced security features
- Improved autoscaling mechanisms
- Better networking capabilities
- More efficient resource management
Check the release notes for your specific version jump and pick one or two features to implement right away.
D. Documenting the upgrade process for future iterations
The upgrade went smoothly? Document exactly what you did while it’s fresh:
- Commands executed
- Issues encountered and how you solved them
- Time required for each step
- Team members involved and their roles
- Version-specific quirks
This isn’t busywork – it’s your survival guide for next time. Future you will be grateful.
E. Optimizing cluster configuration based on new capabilities
Your upgraded cluster has new powers – use them! Review your current configuration and look for optimization opportunities:
- Update deprecated API versions in your manifests
- Refine resource requests and limits based on actual usage
- Implement new admission controllers if available
- Review and update network policies
- Consider adopting newer Kubernetes patterns that weren’t available before
Remember that optimization is an ongoing process, not a one-time task after an upgrade.
Advanced EKS Upgrade Scenarios
A. Managing multi-cluster environments efficiently
Running multiple EKS clusters isn’t just a luxury – it’s often a necessity. Whether you’re separating dev/test/prod environments or distributing workloads across regions, upgrading becomes exponentially complex.
The key? Automation and consistency. Tools like Terraform or AWS CDK become your best friends here. With infrastructure as code, you can standardize your upgrade process across all clusters.
For those juggling 10+ clusters, consider a tiered approach:
- Upgrade canary clusters first
- Monitor for 48-72 hours
- Roll out to non-critical environments
- Finally upgrade production
Many teams create dedicated upgrade pipelines that:
- Take snapshots of critical resources
- Apply upgrades sequentially
- Run validation tests between steps
- Can automatically rollback if predefined metrics fall below thresholds
What about configuration drift? It’s the silent killer of smooth upgrades. Using GitOps tools like Flux or ArgoCD helps maintain consistent states across all your clusters and makes discrepancies immediately visible.
B. Handling complex networking configurations
Network upgrades can make even seasoned engineers break into a cold sweat. Custom CNI configurations, service meshes, and ingress controllers add layers of complexity to your EKS upgrades.
Before touching anything, map your entire network topology. Document every custom configuration, especially if you’ve tweaked the VPC CNI plugin or implemented advanced routing.
Some common networking pitfalls during upgrades:
- Security group rule mismatches
- CIDR block exhaustion
- Load balancer reconfiguration issues
- Service mesh compatibility breaking
For complex setups, create a parallel test environment that mirrors your production networking. Yes, it costs more, but it’s cheaper than production downtime.
If you’re running Istio, Linkerd, or any other service mesh, check their compatibility matrix against your target EKS version. These often lag behind Kubernetes releases, and upgrading out of sync can lead to mysterious connectivity issues.
C. Upgrading clusters with specialized add-ons and extensions
Custom add-ons make your cluster uniquely yours – and uniquely challenging to upgrade. Every specialized component needs special attention.
The most common troublemakers:
- Custom storage drivers
- GPU operators
- Specialized metrics collectors
- Legacy operators
When upgrading clusters with custom add-ons, create a comprehensive inventory. For each component, answer:
- Is it officially supported on the target EKS version?
- Does it require upgrading before, during, or after the EKS upgrade?
- What’s the rollback plan if it fails?
For mission-critical add-ons, maintain parallel implementations where possible. This gives you an escape hatch if one breaks during the upgrade.
Storage deserves extra caution. PersistentVolumes are stateful resources, and botched storage driver upgrades can lead to data loss. Always backup volumes before upgrading, and consider using AWS Backup for EKS as an additional safety net.
D. Addressing upgrade challenges in highly regulated environments
Financial services, healthcare, and government sectors face extra hurdles when upgrading EKS. Compliance requirements don’t pause just because you’re upgrading.
In regulated environments:
- Document everything. Create detailed change management records including risk assessments, rollback procedures, and approval chains.
- Schedule longer maintenance windows. Rushing is your enemy when audit trails matter.
- Implement enhanced monitoring during and after upgrades.
Many regulated industries require preserving evidence of security controls throughout the upgrade. Tools like AWS Config and CloudTrail are invaluable here – they create immutable records of your compliance state.
For clusters handling sensitive data, consider a blue/green approach rather than in-place upgrades. This maintains complete separation between versions and allows comprehensive testing before traffic shifts.
Remember those change approval boards? Give them detailed reports comparing security features between your current and target EKS versions. Highlighting security improvements can accelerate approval processes.
Automating the EKS Upgrade Lifecycle
Building CI/CD pipelines for cluster management
Want to stop the 3 AM cluster upgrade panics? Automation is your best friend.
Building a robust CI/CD pipeline for your EKS clusters isn’t just nice-to-have—it’s essential. Start with tools like Jenkins, GitLab CI, or AWS CodePipeline to orchestrate your cluster management workflows.
The secret sauce? A well-structured pipeline that:
- Validates your cluster configurations
- Applies changes in staging environments first
- Rolls back automatically if health checks fail
- Notifies the right people at the right time
# Example pipeline stage for EKS version validation
eksctl update cluster --name=production-cluster --version=1.24 --dry-run
Infrastructure as Code approaches to EKS upgrades
Clicking around the AWS console for upgrades is like performing surgery with oven mitts. Don’t do it.
With tools like Terraform, AWS CDK, or eksctl configs, you can define your entire EKS infrastructure in code. This approach gives you:
- Version control for your infrastructure
- Predictable upgrade paths
- Easy rollbacks when things go sideways
- Repeatable processes across multiple clusters
Most teams find success with a modular approach:
module "eks" {
source = "terraform-aws-modules/eks/aws"
version = "18.0.0"
cluster_version = "1.24"
# Additional configuration...
}
Creating self-healing and self-upgrading architectures
The gold standard? EKS clusters that upgrade themselves.
This requires thinking beyond just the control plane. Consider:
- Node groups with auto-scaling and automatic updates
- Graceful pod eviction during upgrades
- Cluster autoscaler to maintain capacity during rolling updates
- Proper readiness/liveness probes on all workloads
Your goal: zero-downtime upgrades that happen without manual intervention.
Implementing automated testing for version compatibility
Ever upgraded your cluster only to watch critical workloads crash and burn? Not fun.
Create a comprehensive test suite that runs against candidate EKS versions:
- Integration tests for all critical apps
- Performance benchmarks to catch degradation
- Security scans to verify compliance
- Compatibility checks for custom admission controllers or CRDs
Run these tests in an isolated environment that mirrors production as closely as possible. Only promote EKS versions that pass your test gauntlet with flying colors.
Staying current with EKS upgrades is crucial for maintaining security, performance, and access to the latest Kubernetes features. Through proper assessment, methodical control plane upgrades, careful worker node management, and thorough post-upgrade validation, you can minimize disruption while keeping your infrastructure cutting-edge. The process becomes more manageable with each cycle as you refine your approach.
As your organization matures, consider implementing automation for your EKS upgrade lifecycle. Tools like eksctl, Terraform, and custom CI/CD pipelines can transform manual procedures into repeatable, predictable processes. Whether you’re managing a single cluster or dozens, investing time in upgrade preparation and automation will yield significant operational benefits and help maintain a robust, secure Kubernetes environment on AWS.