The Ultimate EKS Cluster Survival Guide

Upgrading an EKS cluster may seem like a complex and challenging task, but with the right tools and tips, it can be done smoothly and successfully. This article will focus on practical tips and essential tools to help you navigate the process confidently and efficiently. The guidelines provided here will guide you through every step, from initial preparations to using advanced tools for monitoring and managing the cluster. With this information, you can tackle the challenge of upgrading the cluster efficiently and without unnecessary hiccups.

Why Upgrade Your EKS Cluster?
Much like driving a well-maintained and upgraded vehicle, keeping your software and services up-to-date is crucial. Upgrading your EKS cluster offers significant benefits:

• Security: Think of your cluster as a fortress. Each upgrade adds new walls and fortifications to protect your data from attacks.
• Performance: Similar to updating your smartphone’s operating system, each cluster upgrade brings performance improvements, making your system faster and smoother.
• New Features: Upgrades are like receiving new tools for your toolbox. With every upgrade, you gain new features that expand your capabilities.

Support: As older tech devices lose official support, so do older Kubernetes versions. Official support is essential for bug fixes and security updates. However, extended support for outdated versions in AWS can come with a significant cost. This can make upgrading not just a matter of security and performance but also a financially sound decision. Referencing the Official EKS Upgrade Guide Before starting the upgrade process, keeping the official EKS Upgrade Guide handy is crucial. This guide provides detailed, step-by-step instructions tailored to the specific versions you’re upgrading from and to. Pay close attention to any EKS-specific changes that may impact your cluster, as these can vary between versions. Following the official documentation ensures that you don’t miss any critical steps or nuances that could affect the success of your upgrade. Preparation for the Upgrade – Referencing the Official EKS Upgrade Guide

1. System Backup

Before diving into the upgrade, take a moment to consider the implications if something goes wrong. To avoid unpleasant surprises, it’s essential to perform a complete backup of your system. Persistent Volumes Data: Ensure that all critical data is backed up, much like keeping copies of valuable photos. Configurations: Just like preserving your favorite recipes, saving configuration files (YAML/JSON) is crucial. Compatibility Check Ensuring compatibility across your EKS cluster is vital before proceeding with the upgrade. Pay attention to API changes that might affect your services:

• New API Additions: Introduce new features that could enhance your cluster’s functionality.
• Deprecation of Existing APIs: Older APIs might be removed, necessitating updates to your services.
• Changes to API Interfaces: Small interface adjustments may require you to modify your configurations.

Tools for Compatibility Check To identify potential compatibility issues, kubent (Kubernetes Event-driven Native Testing) is a highly recommended tool. kubent scans your cluster for deprecated or incompatible APIs, helping you address issues before they cause disruptions kubent is a plugin for kubectl that helps you detect resources in your Kubernetes cluster that use deprecated or removed APIs. This tool is crucial for ensuring your cluster remains compatible with the new Kubernetes version you’re upgrading. Although kubent is powerful on its own, you can also use other tools like Pluto for a more comprehensive scan. Installing kubent To install kubent, you’ll need to use krew, a plugin manager for kubectl that simplifies the process of adding and managing plugins like kubent. Using kubent to Scan the Cluster After installing kubent, you can run it to scan your cluster. Here’s an example of what the output might look like:  

 NAMESPACE
 NAME
 KIND
 VERSION
 default
 my-deployment
 Deployment
 apps/v1beta1
 kube-system my-ingress-controller
 DaemonSet
 extensions/v1beta1

In this output, kubent has identified that my-deployment is using an outdated API version (apps/v1beta1). Similarly, my-ingress-controller is using an API version (extensions/v1beta1) that might be deprecated or removed in the Kubernetes version you’re upgrading to. These findings indicate that you need to update these resources to use supported API versions before proceeding with the upgrade.

Using Additional Tools

While kubent is highly effective, tools like Pluto can provide additional insights or cross-verification, ensuring no deprecated APIs are missed. Running these tools together gives you a more comprehensive view of your cluster’s compatibility status.By carefully reviewing the output from kubent and updating the identified resources, you can mitigate potential issues, ensuring a smoother upgrade process.

3. CLI Tools Update

Just as you would update your tools for a project, it’s crucial to ensure your CLI tools are up-to-date: pip install awscli –upgrade -kubectl: Instead of platform-specific instructions, it’s best to refer to the official kubectl installation guide. This guide provides step-by-step instructions tailored to your operating system and architecture, ensuring you install the correct version and configuration for your environment. Updating Essential Components Each cluster has its own essential components that may require updates before an upgrade. It’s important to review the specific components in your cluster and ensure they are updated to the latest versions. Here are examples of components that might need to be changed or updated:

• CoreDNS: A crucial component for DNS resolution within your cluster.
• kube-proxy: Handles network rules on each node.
• VPC CNI: Manages network interface allocation for your pods.

After identifying the components that need updating, you should follow the appropriate steps to update them. Here’s how you might approach updating the components mentioned above: Example Updates:

• CoreDNS:

kubectl get deployment coredns -n kube-system -o yaml | grep image If the version is outdated, update CoreDNS as per the EKS documentation.

• kube-proxy:

kubectl get daemonset kube-proxy -n kube-system -o yaml | grep image If necessary, update kube-proxy to ensure compatibility with the new Kubernetes version.

• VPC CNI:

kubectl get daemonset aws-node -n kube-system -o yaml | grep image Make sure the VPC CNI plugin is updated to the latest version provided by AWS .Note: These examples are meant to illustrate the process. Your cluster may have different components that require updates, so it’s essential to check what needs to be updated in your specific environment. Tools for the Upgrade

1. eksctl

Like working with advanced tools in a workshop, **eksctl** provides convenient commands for upgrading the cluster: *Upgrading the Cluster: eksctl upgrade cluster –name <cluster_name> –version <new_version>

2. kubectl

The Kubernetes command-line tool, much like a multifunctional tool, allows managing the cluster: *Checking Component Status: kubectl get deployments –namespace kube-system

3. AWS Management Console

The graphical management tool of AWS, akin to a command center, allows upgrading the cluster intuitively: *Upgrading Through the Console: – Log in to the AWS Management Console. – Navigate to EKS and open your cluster. – Select “Update version” and upgrade to the desired version.

Post-Upgrade Monitoring

After completing the upgrade, it’s essential to monitor your cluster closely to ensure everything is functioning as expected. Use your observability tools, such as Grafana, Datadog, Prometheus, or others already in place, to track the following:

• Cluster Performance: Verify that the overall performance metrics (CPU, memory, disk I/O) remain consistent and within expected ranges.
• Application Errors: Monitor for any increase in application errors, including logs for warning or error messages that may indicate issues introduced by the upgrade.
• Latency: Check for changes in response times and latency across your services to ensure the upgrade hasn’t introduced performance bottlenecks.
• Resource Usage: Ensure that resource usage patterns (e.g., pod CPU and memory usage) are consistent with pre-upgrade levels and that no unexpected spikes occur.
• Network Traffic: Monitor network traffic and communication between pods to ensure that all services are communicating properly and there are no disruptions.

By focusing on these key areas, you can quickly identify and address any issues that may arise post-upgrade, ensuring a smooth transition and stable operation of your cluster.

Conclusion

Upgrading an EKS cluster is a process that requires a great deal of patience and precision. I’ve realized how crucial it is to plan ahead, ensure compatibility, and perform backups. This process is an opportunity to learn about managing large-scale systems and the importance of every small detail along the way. Despite the challenges, it is a vital and rewarding task because, in the end, it provides us with more stable and secure systems. This process helps keep clusters up to date and enriches our knowledge and confidence in the technology we use daily.