Amazon EKS clusters running on Amazon Linux 2 (AL2) need an upgrade path to Amazon Linux 2023 for enhanced security, performance, and long-term support. This EKS node OS upgrade guide walks DevOps engineers, platform teams, and cloud architects through the complete AL2 to AL2023 migration process.
Migrating your EKS node groups from AL2 to AL2023 requires careful planning and execution to avoid downtime and compatibility issues. We’ll cover the key differences between these operating systems and why the upgrade matters for your Kubernetes workloads. You’ll learn proven Amazon EKS migration best practices for assessing your current environment and planning a smooth transition.
This EKS cluster migration guide includes step-by-step instructions for executing the node group migration safely and validating your upgraded infrastructure. We’ll also tackle common troubleshooting scenarios that teams encounter during the migration process, helping you resolve issues quickly and maintain cluster stability.
Understanding AL2 vs AL2023 Differences
Key architectural improvements in AL2023
Amazon Linux 2023 brings major architectural changes that make EKS node upgrade worthwhile. The new OS uses a modern kernel with enhanced container runtime performance and improved memory management. AL2023 features a streamlined package system that reduces attack surface while boosting system responsiveness. The AL2 to AL2023 migration delivers better resource isolation for Kubernetes workloads through updated cgroups v2 implementation and advanced process scheduling algorithms.
Performance benefits and resource optimization
The Amazon Linux 2023 EKS platform shows measurable performance gains across CPU, memory, and I/O operations. Boot times decrease by up to 30% compared to AL2, while container startup latency drops significantly. The optimized kernel scheduler handles multi-threaded workloads more efficiently, reducing context switching overhead. Memory allocation improvements mean better pod density per node, making your EKS cluster migration guide investment pay off through reduced infrastructure costs and faster application response times.
Security enhancements and compliance features
AL2023 ships with hardened security defaults and automated vulnerability patching capabilities. The OS includes enhanced SELinux policies specifically tuned for container environments and Kubernetes security contexts. Built-in compliance frameworks support SOC 2, PCI DSS, and HIPAA requirements out of the box. The EKS node OS upgrade provides real-time threat detection and automated security updates without requiring manual intervention or pod restarts during your Kubernetes node migration AWS process.
Package management and software updates
The new dnf package manager replaces yum and offers faster dependency resolution with better error handling. AL2023 uses deterministic package builds with cryptographic signing for supply chain security. Rolling updates happen automatically in the background without disrupting running workloads. The EKS AL2023 upgrade steps include simplified package customization through modular repositories, allowing teams to maintain consistent software versions across development and production environments while following AWS EKS migration best practices.
Pre-Migration Planning and Assessment
Inventory existing EKS cluster configurations
Start by documenting your current EKS cluster setup, including node group configurations, instance types, and AMI versions. Catalog all managed and self-managed node groups, noting their current Amazon Linux 2 versions and any custom configurations. Record security groups, subnets, and IAM roles attached to your nodes. This comprehensive Amazon EKS node upgrade inventory helps identify potential compatibility issues before starting your AL2 to AL2023 migration.
Identify application dependencies and compatibility issues
Examine your workloads for AL2-specific dependencies that might break during the EKS node OS upgrade. Check for hardcoded paths, systemd services, or packages that differ between operating systems. Test containerized applications against AL2023 environments to spot issues early. Pay special attention to monitoring agents, security tools, and custom init scripts. Document any third-party software that requires specific OS versions for your EKS cluster migration guide planning.
Create migration timeline and rollback strategies
Develop a detailed migration schedule that minimizes disruption to your production workloads. Plan for blue-green deployments or rolling updates, scheduling the Amazon Linux 2023 EKS upgrade during low-traffic periods. Create comprehensive rollback procedures including AMI snapshots and node group restoration steps. Define clear success criteria and testing checkpoints throughout your AWS EKS migration best practices timeline. Establish communication protocols for stakeholders and prepare emergency procedures if the Kubernetes node migration AWS process encounters critical issues.
Setting Up Your Migration Environment
Configure New AL2023 Node Groups
Create dedicated AL2023 node groups alongside your existing AL2 infrastructure using AWS EKS console or Terraform. Start with a minimal configuration matching your current AL2 setup, including instance types, scaling parameters, and security groups. This Amazon EKS node upgrade approach allows gradual workload migration while maintaining service availability. Configure the new node groups with identical subnet placement and security policies to ensure seamless pod scheduling during the AL2 to AL2023 migration process.
Establish Parallel Infrastructure for Testing
Deploy a complete testing environment that mirrors your production setup but runs exclusively on AL2023 nodes. This parallel infrastructure should include identical applications, networking configurations, and resource allocations. Use separate namespaces or dedicated test clusters to validate workload compatibility before the actual EKS node OS upgrade. Run comprehensive application tests, performance benchmarks, and integration checks to identify potential issues early in your Amazon Linux 2023 EKS migration timeline.
Implement Monitoring and Logging for Both Environments
Set up enhanced monitoring using CloudWatch Container Insights, Prometheus, or your preferred observability stack to track both AL2 and AL2023 node performance metrics. Configure detailed logging for system events, application behaviors, and resource utilization patterns during the EKS cluster migration guide implementation. Establish baseline metrics from your current AL2 environment and compare them against AL2023 performance to validate the upgrade benefits and catch any anomalies.
Prepare Backup and Disaster Recovery Procedures
Document complete rollback procedures including node group deletion, pod rescheduling strategies, and data recovery steps before starting your Kubernetes node migration AWS process. Create automated backup scripts for critical configurations, persistent volumes, and application state. Test your disaster recovery procedures in the parallel environment to verify recovery time objectives. Prepare emergency contact lists and escalation procedures to handle any critical issues during the AWS EKS migration best practices implementation phase.
Executing the Node OS Migration
Deploy AL2023 nodes alongside existing AL2 nodes
Start your Amazon EKS node upgrade by creating new node groups running Amazon Linux 2023 while keeping existing AL2 nodes active. Use the AWS CLI or EKS console to provision AL2023 node groups with identical instance types, subnets, and security groups. This blue-green deployment approach ensures zero downtime during your EKS node OS upgrade. Configure the new node groups with appropriate taints and labels to prevent workloads from automatically scheduling until you’re ready. Test the node group creation thoroughly to verify networking, IAM permissions, and cluster integration work correctly.
Gradually drain workloads from AL2 nodes
Begin your EKS cluster migration by cordoning AL2 nodes to prevent new pods from scheduling. Use kubectl drain commands to gracefully evict pods from old nodes, allowing them to reschedule on AL2023 nodes. Apply PodDisruptionBudgets to maintain application availability during the transition. Drain nodes in batches rather than all at once to maintain cluster stability. Monitor pod rescheduling carefully and verify that critical workloads migrate successfully. This gradual approach minimizes service disruptions and gives you time to address any compatibility issues that arise during the Amazon EKS node group migration.
Validate application functionality on new nodes
Run comprehensive testing to ensure applications function correctly on Amazon Linux 2023 nodes. Execute health checks, performance tests, and integration tests to verify workload compatibility. Pay special attention to applications that depend on specific kernel versions, system libraries, or container runtime features. Check that persistent volumes mount correctly and network policies work as expected. Review application logs for any errors or warnings that might indicate compatibility issues. Document any differences in application behavior and create remediation plans if needed. This validation step is crucial for a successful AWS EKS migration following best practices.
Monitor cluster performance during transition
Track key metrics throughout your EKS AL2023 upgrade using CloudWatch, Prometheus, or other monitoring tools. Watch CPU utilization, memory consumption, network throughput, and pod startup times across both AL2 and AL2023 nodes. Set up alerts for unusual patterns or performance degradation. Monitor cluster autoscaling behavior to ensure new pods schedule correctly on AL2023 nodes. Pay attention to container image pull times, as AL2023 might have different caching behavior. Use Kubernetes dashboard or kubectl commands to monitor pod distribution and node resource allocation. Keep detailed logs of the migration process for troubleshooting and future reference.
Remove deprecated AL2 node groups
Complete your Kubernetes node migration AWS process by safely removing the old AL2 node groups. Double-check that no critical workloads remain on AL2 nodes before deletion. Verify that all persistent volumes have been properly migrated and are accessible from AL2023 nodes. Update any infrastructure-as-code templates or automation scripts to reflect the new AL2023 configuration. Remove old launch templates, Auto Scaling groups, and any associated resources. Clean up any node-specific monitoring configurations or log forwarding rules. Document the final cluster configuration and update your operational procedures to reflect the new Amazon Linux 2023 EKS setup for future maintenance and scaling activities.
Post-Migration Optimization and Validation
Fine-tune AL2023 performance settings
Amazon EKS node OS upgrade performance can be significantly improved by adjusting AL2023-specific configurations. Start by enabling systemd-oomd for better memory management and configure the new cgroup v2 hierarchy that comes with Amazon Linux 2023. Update container runtime settings to leverage improved containerd optimizations. Monitor CPU throttling with the enhanced kernel schedulers and adjust kubelet resource reservations based on AL2023’s reduced memory footprint. Review network buffer settings as AL2023 includes updated networking stack improvements that may require different tuning parameters compared to your previous AL2 configuration.
Update security configurations and policies
EKS AL2023 upgrade steps require immediate attention to security policy updates since Amazon Linux 2023 introduces several security enhancements. Enable the new SELinux targeted policy if your workloads support it, and update firewall rules to work with the modernized netfilter framework. Review and update any custom security profiles, particularly those related to container isolation and syscall filtering. Verify that your Pod Security Standards still function correctly with AL2023’s updated kernel security modules. Update any custom admission controllers or security scanning tools to recognize AL2023’s new package signatures and security contexts.
Verify all workloads are running optimally
AWS EKS migration best practices emphasize thorough workload validation after completing your Amazon EKS node group migration. Run comprehensive health checks on all deployed applications, paying special attention to services that depend on specific kernel features or system libraries. Monitor application startup times as AL2023’s faster boot sequence may affect initialization order. Check persistent volume mounts and storage performance, especially for workloads using local storage or specific filesystem features. Validate that all monitoring and logging agents are collecting data correctly, as some may need updates to work optimally with AL2023’s enhanced observability features and updated system paths.
Troubleshooting Common Migration Issues
Resolve container runtime compatibility problems
Container runtime issues often surface when switching from AL2 to AL2023 during your Amazon EKS node upgrade. The most common problem involves containerd version mismatches between your existing workloads and the new operating system. Check your pod specifications for deprecated runtime configurations and update any hardcoded containerd socket paths. Verify that your container images are compatible with the newer containerd version in AL2023. If applications fail to start, examine the kubelet logs for runtime-specific errors and adjust your deployment manifests accordingly.
Address networking and connectivity challenges
Network configuration differences between AL2 and AL2023 can disrupt your EKS cluster migration. The new OS uses updated iptables rules and firewall configurations that might block existing traffic patterns. Start by comparing the CNI plugin versions and ensure your VPC-CNI is compatible with AL2023. Check security group rules and NACLs if pods can’t reach external services. DNS resolution problems are common – verify that CoreDNS pods are running properly and that your applications use the correct service discovery mechanisms for the updated networking stack.
Fix application-specific configuration conflicts
Applications may encounter configuration conflicts when migrating to Amazon Linux 2023 EKS nodes due to changed file system layouts and updated package versions. Legacy applications expecting specific library versions or file paths from AL2 will need updates. Review your application logs for missing dependencies or library incompatibilities. Update any hardcoded paths pointing to AL2-specific locations. Consider using init containers to verify environment requirements before your main application starts, and adjust resource limits if the new OS has different memory or CPU allocation patterns.
Handle persistent volume migration complications
Persistent volume issues during EKS node OS upgrade typically involve mounting failures or data accessibility problems. The updated kernel in AL2023 may require different volume drivers or mount options. Check that your CSI drivers are compatible with the new operating system version. If using EBS volumes, verify that the AWS EBS CSI driver version supports AL2023. For applications experiencing data corruption or mounting errors, ensure that volume permissions and ownership settings are correctly configured for the new node group’s security context requirements.
Making the jump from AL2 to AL2023 for your Amazon EKS nodes might seem daunting at first, but breaking it down into manageable steps makes the process much more straightforward. We’ve walked through everything from understanding the key differences between the operating systems to planning your migration strategy, setting up your environment, and actually executing the switch. The performance improvements and enhanced security features of AL2023 make this upgrade well worth the effort.
Don’t rush the process – take time to properly assess your current setup and test everything in a staging environment first. Keep those troubleshooting tips handy, and remember that most migration hiccups are easily resolved with the right approach. Start planning your AL2023 migration today, and your future self will thank you for the improved performance and streamlined management that comes with Amazon’s latest node operating system.
