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The Definitive Guide to Kubernetes Cluster Upgrades

Kubernetes continues to play a pivotal role in orchestrating containerized applications with its cloud-native capabilities. Of course, capabilities like flexibility and scalability mean organizations must be extra vigilant, especially when it comes to maintaining the health and efficiency of Kubernetes clusters. 

This brings us to the critical topic of cluster upgrades, a task often met with a mix of anticipation and anxiety by DevOps, platform engineers, SREs, and cloud engineers who are typically in charge of such operations. 

Upgrading Kubernetes clusters is not just about keeping up with the latest versions; it’s a crucial practice for ensuring your applications’ security, reliability, and performance. Each new Kubernetes release not only patches vulnerabilities but also introduces new features and improvements that can significantly enhance your operational capabilities. Still, each upgrade process can be an overwhelming task. 

Focusing on the major cloud platforms, Amazon EKS, AKS, and GKE, this post will explore the challenges and best practices associated with upgrading clusters. We’ll also discuss the importance of timely updates to avoid the pitfalls of running on outdated versions, which can suffer from security vulnerabilities, performance issues, lack of support for newer features, and increased costs. 

Notably, the cost of maintaining unsupported, out-of-date AWS cluster versions can increase by as much as six times, underscoring the financial impact alongside the operational risks of not upgrading clusters.

Understanding the Challenges of Cluster Upgrades

Navigating the path of cluster upgrades is filled with obstacles that test the nerve of even the most seasoned teams. Below, we discuss some of the hurdles they face. 

Scale and Complexity

The substantial scale and complexity of modern Kubernetes deployments significantly complicate the upgrade process. For instance, a company may run numerous Kubernetes clusters across different cloud environments—each tailored to specific applications and business requirements. This multicluster strategy enhances resilience and flexibility but adds complexity during upgrades.

Consider a financial services firm using Kubernetes to manage applications handling real-time transaction processing, data analysis, and customer interfaces. Each application might reside on a separate cluster optimized for its specific workload, possibly distributed across AWS for compute-heavy tasks, Azure for integration with Office 365 services, and Google Cloud for AI and machine learning capabilities. Upgrading any single cluster—such as applying a new Kubernetes version to enhance security or performance—necessitates detailed cross-platform coordination to ensure consistent network configurations, persistent storage compatibility, and uninterrupted service.

Moreover, the interconnected nature of these systems means that changes made in one cluster, such as updating network policies or storage classes, can have cascading effects on others. For example, altering a network configuration might require subsequent modifications to firewall rules and load balancers in other clusters to maintain smooth inter-cluster communication. Each adjustment must be planned and executed precisely to avoid service disruption, emphasizing the need for a well-orchestrated upgrade strategy that accounts for the entire system’s complexity.

Kubernetes API Changes and Complications

A critical component of managing Kubernetes upgrades is navigating the evolving landscape of API versioning and deprecation. As Kubernetes continues to develop, each new release may deprecate or entirely remove older APIs, which can substantially impact applications dependent on those APIs.

Consider a scenario where a production environment depends on a Kubernetes API that is deprecated and removed in a subsequent release. The upgrade process in this case is not a simple task of updating the cluster. It involves substantial changes to the application code, potentially impacting deployment management and service communication within the cluster. This complexity highlights the need for meticulous planning and coordination during upgrades.

Consider a real-world scenario where a telecommunications company uses a specific Kubernetes API for network policy management that is set to be deprecated. With the release of a new Kubernetes version, the company must revise or completely rewrite the network management components of their applications to accommodate changes in the API. This process involves careful coordination and testing to ensure that the new API integrations maintain network integrity and security standards, all while implementing these changes across multiple clusters that may each have different operational requirements and timelines for upgrades.

Managing Kubernetes upgrades is not just a technical challenge but also a procedural one. Developers and system administrators must maintain a continuous learning process, keeping themselves updated through Kubernetes release notes, community discussions, and even direct contributions to the Kubernetes project. This proactive approach enables them to anticipate system impacts, plan upgrades, and ensure uninterrupted service continuity.

Importance of Timely Upgrades

Delaying cluster upgrades in Kubernetes is a risk that organizations cannot afford. Running on outdated versions not only leaves clusters vulnerable to security threats but also deprives them of the latest features and performance enhancements. These upgrades are crucial not just for security and functionality but also for preventing the cluster from reaching end-of-life (EoL), a point at which it no longer receives support or security patches, increasing the risk of operational failures.

Real-life incidents, such as the Reddit Pi Day outage, illustrate the importance of timely and well-planned upgrades. This outage was due to a series of compounded issues, including deprecated features and overwhelmed databases, underscoring the potential consequences of delayed maintenance and upgrade cycles. 

According to Reddit’s engineering team, the outage was worsened by outdated system components that struggled under peak load conditions. This incident highlights several critical lessons concerning best practices:

  • Proactive upgrades: Staying ahead with upgrades could prevent scenarios where systems cannot handle unexpected loads.
  • Capacity planning: Regular assessments of system capacities and performance thresholds are essential to ensure they can handle traffic surges.
  • Comprehensive testing: Extensive testing is necessary before deploying upgrades to uncover any potential issues that could lead to system failures.

By analyzing such outages, organizations can better understand the risks of technical debt and the absolute necessity for a proactive approach to system upgrades. This not only ensures system reliability and security but also maintains operational efficiency and supportability over time.

Integrating Upgrades into SRE Workflows

Incorporating cluster upgrades into SRE (Site Reliability Engineering) workflows is a detailed process that directly impacts the stability and reliability of Kubernetes environments. Here’s how organizations can integrate these upgrades effectively.


The planning phase is crucial and should be as detailed as possible. SRE teams must collaborate to understand the upgrade’s scope and create a comprehensive impact analysis and risk assessment. This includes:

  • Mapping dependencies: Understand how different system components interact and which ones will be affected by the upgrade.
  • Reviewing Kubernetes release notes: Identify critical changes, especially those around deprecated APIs and security fixes that might impact existing applications.
  • Setting clear rollback criteria: Establish thresholds and conditions under which an upgrade should be rolled back to maintain system stability.


Execution must be more than merely following the plan—it requires precision and adaptability:

  • Implementing canary releases: Gradually roll out the upgrade to a small subset of the environment to test the impact without affecting the entire system.
  • Automated testing and validation: Use automation to execute tests and immediately capture any deviations from expected performance.
  • Real-time monitoring and decision-making: SRE teams should use monitoring tools to observe the upgrade’s effect in real-time and make data-driven decisions to proceed or rollback.

Monitoring & Analysis

After the upgrade, the focus should shift to rigorous monitoring and systematic analysis:

  • Benchmarking performance: Compare the performance of the upgraded clusters against pre-upgrade benchmarks to understand any deviations or improvements.
  • Identifying and resolving issues: Quickly identify and resolve any issues that emerge post-upgrade using detailed logs and monitoring data.
  • Documenting lessons learned: Capture insights and feedback from the upgrade process to refine future upgrade strategies.

This structured approach not only aligns with the principles of SRE but also ensures that cluster upgrades are handled to minimize disruptions and maximize system integrity and reliability. By focusing on detailed planning, careful execution, and thorough post-upgrade analysis, organizations can better manage the complexities associated with maintaining large-scale Kubernetes environments.

General Upgrade Best Practices

Managing Kubernetes cluster upgrades, especially when dealing with hundreds or thousands of clusters, requires a robust and sophisticated approach beyond simple commands. The real challenge lies in the coordination and scalability of these processes.

Comprehensive Inventory and Management

Begin by establishing a centralized management system that tracks every cluster’s configuration and current status. This system should:

  • Catalog all clusters: Maintain a detailed inventory that includes each cluster’s version, configuration settings, and health status.
  • Treat clusters as groups: On a scale of over a dozen clusters, you should start thinking in ‘Fleet’ terms. Cluster groups can be segmented by business units, different teams, environments, or cloud providers. Imagine upgrading all your AWS clusters in one go, or pushing a change to all production clusters. This approach streamlines cluster maintenance at scale but also enhances standardization and control for the cluster operators. 
  • Automate version tracking: Utilize tools that automatically detect and report the current versions of Kubernetes running across different clusters and flag those eligible for upgrades.

Complexity in Scaling Upgrades

Upgrading multiple clusters can be highly complex and error-prone if not managed carefully. This involves:

  • Synchronized upgrades: Develop a strategy for phased rollouts that prioritizes clusters based on criticality and interdependencies among applications.
  • Customized upgrade paths: Each cluster may have unique requirements and constraints, requiring tailored upgrade plans considering specific configurations and workload sensitivities.

Tooling and Automation

Leverage automation to streamline the upgrade process via:

  • Automated health checks: Before upgrading, automate cluster performance and stability assessments to ensure they meet the necessary criteria for a successful upgrade.
  • Kubernetes-native tools: Use advanced tools like Komodor to help visualize, monitor, and troubleshoot Kubernetes environments. These tools provide insights into dependencies within the cluster and highlight potential issues before they cause problems during an upgrade. Komodor will also alert you on impending EoL versions, and any related API deprecations.

Risk Management and Contingency Planning

Plan comprehensively for potential failures using:

  • Backup systems: Ensure all data is backed up and easily restorable in case an upgrade fails.
  • Rollback procedures: Establish clear and tested rollback procedures that can be quickly implemented if an upgrade does not go as planned.

Ongoing Monitoring and Validation

After the upgrade, make sure to:

  • Monitor system health: Continuously monitor the clusters for any signs of instability or degradation in performance.
  • Perform validation tests: Conduct thorough validation tests to confirm that the upgraded clusters are functioning as expected and meeting performance benchmarks.

The above measures underscore the complexity and demands of managing Kubernetes upgrades at scale. It necessitates a blend of strategic planning, advanced tooling, and careful execution to ensure that upgrades enhance system performance without disrupting ongoing operations.

Platform-Specific Upgrade Tools

While each cloud provider presents unique tools and services that can assist with Kubernetes cluster upgrades, relying solely on these platforms may not be the most efficient way to manage cluster versions, especially when dealing with large-scale environments. 

Below, we discuss some of the tools available through the major cloud platforms that can be integrated into a broader, more comprehensive upgrade strategy.

Amazon Elastic Kubernetes Service (EKS)

Leverage the AWS Management Console or the AWS CLI to upgrade clusters. Use Amazon EKS’s built-in update features to apply the latest security patches and Kubernetes versions. Also, consider utilizing EKS-managed node groups to simplify node upgrades.

Automated EKS cluster upgrades are possible using eksctl with the following command. For the new-k8s-version, it’s suggested to choose from the versions listed from the pre-upgrade checklist stage:

eksctl upgrade cluster –name your-cluster-name –region your-region –version new-k8s-version

Azure Kubernetes Service (AKS)

Utilize the AKS upgrade feature through the Azure portal or Azure CLI. AKS’s node image upgrade capabilities keep your nodes current with the latest OS and runtime updates.

You can use the Azure CLI for the AKS cluster upgrade:

az aks upgrade –name your-cluster-name –resource-group your-resource-group –kubernetes-version new-k8s-version 

Google Kubernetes Engine (GKE)

GKE automatically upgrades your clusters and node pools, ensuring you’re always running on the latest version. Use GKE’s release channels to automatically receive updates deemed stable and suitable for your workload.

You can implement the GKE cluster upgrade using gcloud:

gcloud container clusters upgrade your-cluster-name –cluster-version=new-k8s-version –zone your-zone 

It’s essential to recognize that while these tools are helpful, they are part of a broader toolkit necessary for effectively managing Kubernetes clusters, particularly in complex or large-scale deployments. Integrating these platform-specific tools with advanced management solutions can enhance oversight and control over upgrade processes, ensuring more consistent and reliable operations across all your Kubernetes environments.

Despite the fact that most Kubernetes distributions offer proactive cluster upgrades, you’ll still need a centralized platform to manage all the different distros in a single place. Especially if your organization’s business logic necessitates multi-cloud/hybrid deployments for each BU. 

Advanced Techniques and Tools

Utilizing advanced techniques and tools is essential for optimizing the efficiency, reliability, and security of Kubernetes operations. Automation, alongside specialized software, plays a pivotal role in managing complex environments and minimizing the potential for human error. 

Tools such as Terraform, Ansible, and Kubernetes operators are instrumental in managing cluster configurations and facilitating automated upgrades.

Terraform for Kubernetes Upgrades

To harness Terraform effectively for managing Kubernetes versions, it’s crucial to integrate it into a broader Infrastructure-as-Code strategy. Here’s a detailed approach to using Terraform for Kubernetes upgrades:

  • Version management: Define the Kubernetes version directly within your Terraform configuration to ensure consistency across all environments. For example:

resource “aws_eks_cluster” “example” {

  name     = “your-cluster-name”

  version  = “new-k8s-version”

  // Additional configuration…


  • Module utilization: Use Terraform modules to encapsulate common patterns of resource deployment across your Kubernetes clusters. For instance, you can create a module for setting up and upgrading node groups in a standardized way.
  • State management: Maintain Terraform state files securely, utilizing remote state backends like AWS S3 with state locking via DynamoDB to prevent conflicts during concurrent operations.
  • Workflow automation: Integrate Terraform with CI/CD pipelines for automated testing and rolling out of changes. This setup ensures that any changes, including version upgrades, are thoroughly tested before being applied to production.
  • Rollback plans: Design your Terraform configurations to allow easy rollback to previous versions in case of failures during upgrades. This can be achieved by versioning your Terraform states and ensuring that older states can be re-applied without compatibility issues.

Ansible for Configuration Management

In addition to Terraform, teams can use Ansible to manage the configuration of Kubernetes clusters. Ansible playbooks can automate the application of configurations and ensure they are consistently applied across all nodes in the cluster. 

For example, Ansible can automate the application of security patches or network configuration updates as part of an upgrade process.

Kubernetes Operators

Developing custom Kubernetes operators allows for more granular control over the lifecycle of services running within your clusters. Operators act on Custom Resource Definitions (CRDs) to manage applications and their components in a Kubernetes-native way. They can automate complex tasks like upgrades, backups, and scaling based on the real-time state of the environment.

By leveraging these advanced tools and techniques, organizations can achieve high automation and precision in managing Kubernetes clusters, leading to more stable and secure deployments.


Before we conclude, let’s recap the key best practices and tips provided in this guide for Kubernetes cluster upgrades:

  • Thorough pre-upgrade assessments and planning:
    • Review deployed applications and check for deprecated APIs.
    • Understand the changes and improvements in the new Kubernetes version.
    • Identify the right time for the upgrade to minimize impact on operations.
  • Effective testing and rollback procedures:
    • Implement a robust testing strategy with staging environments.
    • Ensure a rollback plan is in place to revert to the previous version if needed.
  • Platform-specific tools and best practices:
    • Leverage tools offered by cloud providers like AWS, Azure, and Google Cloud.
    • Use these tools within a broader, comprehensive upgrade strategy to manage clusters efficiently.
  • Advanced techniques and tools:
    • Utilize automation and specialized software such as Terraform, Ansible, and Kubernetes operators.
    • Automate as much of the upgrade process as possible to reduce manual errors and streamline operations.
    • Keep the human in the loop! Automate as much as possible but keep the process in check with an experienced human engineer to avoid surprise upgrades and breaking changes.
  • Integration of upgrades into SRE workflows:
    • Align upgrade processes with SRE principles to balance new feature delivery and operational stability.
    • Employ a data-driven approach for assessing risks and strategizing mitigations.
    • Stage ‘play days’ or workshops to train for cluster upgrades in a safe environment.

By understanding the challenges, employing these best practices, and leveraging the right tools and techniques, organizations can streamline the upgrade process and minimize the impact on their operations.

The future of Kubernetes upgrades lies in automation and the integration of intelligent tools that can predict, plan, and execute upgrades with minimal human intervention. Proactive and automated upgrade management will become increasingly crucial as Kubernetes environments become even more complex.

Leveraging Komodor for Enhanced Cluster Upgrades

Komodor offers a Kubernetes management platform designed to simplify the operation and optimization of K8s clusters, including the upgrade process. With features focused on continuous reliability, Komodor provides real-time insights, troubleshooting capabilities, and a holistic view of your Kubernetes ecosystem. Planning, executing, and monitoring cluster upgrades all become easier.

By integrating Komodor into your DevOps stack, you can stop worrying about cluster upgrades, ensuring your system remains secure, up-to-date, and performing at its best. Try Komodor for free today: https://komodor.com/pricing-and-plans/#get-started-popup