<h2 style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="font-weight: bold;"> Introduction </span></h2>
<p style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="color: #000000; font-weight: 400; text-decoration: none; vertical-align: baseline; font-size: 11pt; font-family: 'Arial'; font-style: normal;"> Kubernetes is a powerful container orchestration platform that enables organizations to deploy, scale, and manage containerized applications. As new features and bug fixes are regularly released, it is crucial to keep your Kubernetes clusters up to date. In this article, we will walk through the process of upgrading a Kubernetes cluster from version 1.21 to the latest stable release, version 1.22. </span></p>
<h2 style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="font-weight: bold;"> Before You Begin </span></h2>
<p style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="color: #000000; font-weight: 400; text-decoration: none; vertical-align: baseline; font-size: 11pt; font-family: 'Arial'; font-style: normal;"> Before initiating the upgrade process, it is essential to review the release notes of Kubernetes version 1.22. This will help you understand the changes and improvements introduced in the new release. Additionally, make sure you have performed a backup of your Kubernetes cluster, as an upgrade can sometimes introduce unforeseen issues. </span></p>
<h2 style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="font-weight: bold;"> Step 1: Check Cluster’s Health </span></h2>
<p style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="color: #000000; font-weight: 400; text-decoration: none; vertical-align: baseline; font-size: 11pt; font-family: 'Arial'; font-style: normal;"> Before upgrading, it is important to ensure that your cluster is running smoothly and that there are no existing errors or issues. You can validate your cluster’s health by running the following command: </span></p>
<p style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="color: #000000; font-weight: 400; text-decoration: none; vertical-align: baseline; font-size: 11pt; font-family: 'Arial'; font-style: normal;"> This command will list all the nodes in your cluster. Make sure all nodes are in the “Ready” state. If any nodes are not ready or if there are any other issues, resolve them before proceeding with the upgrade. </span></p>
<h2 style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="font-weight: bold;"> Step 2: Upgrade the Control Plane </span></h2>
<p style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="color: #000000; font-weight: 400; text-decoration: none; vertical-align: baseline; font-size: 11pt; font-family: 'Arial'; font-style: normal;"> To upgrade the control plane, we will use the `kubeadm` utility. Kubeadm is the tool provided by Kubernetes to bootstrap and manage a Kubernetes cluster. Follow the steps below to upgrade the control plane: </span></p>
<h3 style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="font-weight: bold;"> 1. Drain the control plane node: </span></h3>
<p style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="color: #000000; font-weight: 400; text-decoration: none; vertical-align: baseline; font-size: 11pt; font-family: 'Arial'; font-style: normal;"> This command will safely evict all the pods running on the control plane node. The `–ignore-daemonsets` flag ensures that daemonset pods are not evicted. </span></p>
<h3 style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="font-weight: bold;"> 2. Upgrade `kubeadm`, `kubelet`, and `kubectl` packages: </span></h3>
<p style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="color: #000000; font-weight: 400; text-decoration: none; vertical-align: baseline; font-size: 11pt; font-family: 'Arial'; font-style: normal;"> Replace “ with the desired version of Kubernetes (1.22 in this case). </span></p>
<h3 style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><strong><span style="color: #000000; text-decoration: none; vertical-align: baseline; font-size: 11pt; font-family: Arial; font-style: normal;"> 3. Once the packages are upgraded, proceed with upgrading the control plane: </span></strong></h3>
<p style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="color: #000000; font-weight: 400; text-decoration: none; vertical-align: baseline; font-size: 11pt; font-family: 'Arial'; font-style: normal;"> This command will upgrade the control plane components to version 1.22.0. You may modify the version if a newer release is available. </span></p>
<h3 style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="font-weight: bold;"> 4. Upgrade the kubelet configuration: </span></h3>
<p style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="color: #000000; font-weight: 400; text-decoration: none; vertical-align: baseline; font-size: 11pt; font-family: 'Arial'; font-style: normal;"> These commands will reload the kubelet configuration and restart the kubelet service with the updated configuration. </span></p>
<h3 style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="font-weight: bold;"> 5. Uncordon the control plane node: </span></h3>
<p style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="font-weight: bold;"> This command makes the control plane node schedulable again. </span></p>
<h2 style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="font-weight: bold;"> Step 3: Upgrade Worker Nodes </span></h2>
<p style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="color: #000000; font-weight: 400; text-decoration: none; vertical-align: baseline; font-size: 11pt; font-family: 'Arial'; font-style: normal;"> After upgrading the control plane, the next step is to upgrade the worker nodes. Follow the steps below to upgrade the worker nodes: </span></p>
<h3 style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="font-weight: bold;"> 1. Drain the worker node: </span></h3>
<p style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="color: #000000; font-weight: 400; text-decoration: none; vertical-align: baseline; font-size: 11pt; font-family: 'Arial'; font-style: normal;"> Similar to the control plane upgrade, this command will safely evict all the pods running on the worker node, excluding daemonset pods. </span></p>
<h3 style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="font-weight: bold;"> 2. Upgrade `kubeadm`, `kubelet`, and `kubectl` packages: </span></h3>
<p style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="font-weight: bold;"> Replace “ with the desired version of Kubernetes. </span></p>
<h3 style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><strong><span style="color: #000000; text-decoration: none; vertical-align: baseline; font-size: 11pt; font-family: Arial; font-style: normal;"> 3. Once the packages are upgraded, proceed with upgrading the worker node: </span></strong></h3>
<p style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="color: #000000; font-weight: 400; text-decoration: none; vertical-align: baseline; font-size: 11pt; font-family: 'Arial'; font-style: normal;"> This command will upgrade the worker node to match the control plane’s version. </span></p>
<h3 style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="font-weight: bold;"> 4. Uncordon the worker node: </span></h3>
<p style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="font-weight: bold;"> This command makes the worker node schedulable again. </span></p>
<h2 style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="font-weight: bold;"> Step 4: Verify the Upgrade </span></h2>
<p style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="color: #000000; font-weight: 400; text-decoration: none; vertical-align: baseline; font-size: 11pt; font-family: 'Arial'; font-style: normal;"> After upgrading both the control plane and worker nodes, it is crucial to verify that the upgrade was successful. Run the following command to check the cluster’s health: </span></p>
<p style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="color: #000000; font-weight: 400; text-decoration: none; vertical-align: baseline; font-size: 11pt; font-family: 'Arial'; font-style: normal;"> All the nodes should be in the “Ready” state. Additionally, you can check the version of Kubernetes by running: </span></p>
<p style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="color: #000000; font-weight: 400; text-decoration: none; vertical-align: baseline; font-size: 11pt; font-family: 'Arial'; font-style: normal;"> This will display the server version, confirming that the upgrade was completed successfully. </span></p>
<h2 style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;"><span style="font-weight: bold;"> Conclusion </span></h2>
<p style="margin: 0; color: #000000; font-size: 11pt; font-family: 'Arial'; line-height: 1.1500000000000001; orphans: 2; widows: 2; text-align: left; padding: 0pt 0 10pt 0;">Upgrading Kubernetes or OpenShift from version 1.21 to 1.22 involves upgrading the control plane and worker nodes separately. By following the steps outlined in this guide, you can ensure a smooth and error-free upgrade process. Remember to review the release notes for any specific upgrade instructions or prerequisites. Keeping your <a href="https://cloudastra.co/blogs/openshift-vs-kubernetes-a-detailed-comparison">OpenShift vs kubernetes</a> cluster up to date is essential for taking advantage of new features, improvements, and bug fixes.</p>
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Upgrading Kubernetes: A Step-By-Step Guide From Version 1.21 To 1.22

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Upgrading Kubernetes: A Step-By-Step Guide From Version 1.21 To 1.22

Upgrading Kubernetes: A Step-By-Step Guide From Version 1.21 To 1.22

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