want to upgrade aks from 1.21 to 1.25. what are the risks?

Question

we want to upgrade aks from 1.21 to 1.25 as 1.25 is the supported version.

what are the potential risks?

We have made sure all the deprecated APIs are not used anymore. other than that what are the risks with this big version jump.

The upgrade will be done in the 1.21 cluster not creating a new one.

Answer 1

Upgrading from AKS (Azure Kubernetes Service) version 1.21 to 1.25 can introduce several potential risks and challenges, even if deprecated APIs are not in use. Here are some considerations:

Compatibility: Ensure that your applications and dependencies are compatible with Kubernetes 1.25. There might be changes in default configurations, APIs, or behavior that could affect your workloads.

Cluster Stability: The upgrade process itself can disrupt the cluster's stability. Ensure you have a plan to minimize downtime or impact on running applications.

Control Plane Upgrades: Upgrading the control plane (the master nodes) may temporarily affect cluster management operations. Have a strategy for minimizing these disruptions.

Node Pool Configuration: Verify that your node pool configurations are compatible with Kubernetes 1.25. There might be changes in node requirements or configurations.

Network and CNI Plugins: Ensure that your networking and CNI plugins are compatible. Changes in Kubernetes versions might affect network policies and configurations.

Custom Add-ons: If you have custom add-ons or components running in your cluster, make sure they are compatible with the new version.

Third-Party Integrations: Check for compatibility with any third-party tools or services that you have integrated with your AKS cluster.

Backup and Rollback: Implement a backup and rollback strategy in case the upgrade encounters unexpected issues. This ensures you can revert to the previous state if necessary.

Testing: Thoroughly test your applications and workloads in a staging or non-production environment before performing the upgrade in your production cluster.

Documentation: Review the release notes and documentation for Kubernetes 1.25 to understand any breaking changes, new features, or important considerations.

Resource Constraints: Ensure that your AKS cluster has sufficient resources (CPU, memory, and storage) to handle the new version without performance degradation.

Monitoring and Alerts: Enhance your monitoring and alerting systems to promptly detect and respond to any issues that may arise during or after the upgrade.

Rolling Upgrade: Plan for a rolling upgrade strategy to minimize downtime and impact on your applications.

Support and Community: Be prepared to seek support from Azure or the Kubernetes community if you encounter unexpected issues during the upgrade process.

Skill and Knowledge: Ensure your team has the necessary skills and knowledge to troubleshoot and resolve issues specific to AKS and Kubernetes 1.25.

Remember that upgrading a Kubernetes cluster is a complex operation, and careful planning and testing are essential to mitigate risks and ensure a successful upgrade. It's also a good practice to keep your clusters regularly updated to stay current with security patches and feature enhancements.