Upgrading Your OpenShift Cluster: A Step-by-Step Guide

Upgrading your OpenShift cluster is a critical task to ensure you have the latest features, security patches, and performance improvements. Whether you're running OpenShift on-premises or in the cloud, the upgrade process can be straightforward if you follow the right steps. In this blog, we'll walk you through the process of upgrading your OpenShift cluster.

Why Upgrade Your OpenShift Cluster?

Before diving into the upgrade process, it's important to understand why upgrading is essential:

Security Patches: New versions often include critical security fixes.
New Features: Upgrades bring new functionalities and improvements.
Bug Fixes: Resolve known issues and improve stability.
Compatibility: Ensure compatibility with the latest Kubernetes versions and other dependencies.

Pre-Upgrade Checklist

Before starting the upgrade, make sure you have the following:

Backup: Take a full backup of your cluster, including etcd, persistent volumes, and configurations.
Documentation: Review the OpenShift upgrade documentation for your specific version.
Cluster Health: Ensure your cluster is in a healthy state by running oc get nodes and checking for any issues.
Resource Availability: Verify that you have sufficient resources (CPU, memory, storage) to handle the upgrade process.
Compatibility: Check the compatibility of your applications and operators with the new OpenShift version.

Step 1: Check Current Cluster Version

First, determine the current version of your OpenShift cluster:

oc get clusterversion

This command will display the current version and the available updates.

Step 2: Review Release Notes

Before proceeding, review the release notes for the target version. This will help you understand any breaking changes, new features, or deprecated functionalities.

You can find the release notes on the OpenShift GitHub repository or the official Red Hat documentation.

Step 3: Upgrade the Cluster

3.1. Upgrade the Cluster Version

To upgrade your cluster, use the following command:

oc adm upgrade --to-latest

This command will initiate the upgrade process. You can monitor the progress using:

oc get clusterversion

3.2. Upgrade the Cluster Operators

After upgrading the cluster, you need to upgrade the cluster operators. OpenShift will automatically upgrade most of the operators, but you should manually verify their status:

oc get clusteroperators

Ensure all operators are in the Available state. If any operator is stuck, you may need to troubleshoot or manually intervene.

Step 4: Upgrade the Nodes

Once the cluster and operators are upgraded, you need to upgrade the nodes. OpenShift will automatically cordon and drain the nodes before upgrading them. You can monitor the node upgrade process using:

oc get nodes

Wait until all nodes are upgraded and in the Ready state.

Step 5: Verify the Upgrade

After the upgrade is complete, verify that everything is functioning correctly:

Check Cluster Version:
```
 oc get clusterversion
```
Check Cluster Operators:
```
 oc get clusteroperators
```
Check Node Status:
```
 oc get nodes
```
Test Applications: Ensure that your applications are running as expected.

Step 6: Post-Upgrade Tasks

After a successful upgrade, consider the following post-upgrade tasks:

Update Documentation: Update your cluster documentation with the new version and any changes made during the upgrade.
Monitor: Keep an eye on the cluster for any issues that may arise post-upgrade.
Backup: Take a new backup of your cluster after the upgrade.