Upgrade Methods and Strategies

The automated upgrade method uses Ansible playbooks to automate the tasks needed to upgrade a OKD cluster. You can use the inventory file that you used during inital installation to run the upgrade playbooks. Using this method allows you to choose between either upgrade strategy: in-place upgrades or blue-green deployments.

The manual upgrade method breaks down the steps that happen during an automated Ansible-based upgrade and provides the equivalent commands to run manually. Using this method describes the in-place upgrade strategy.

With in-place upgrades, the cluster upgrade is performed on all hosts in a single, running cluster: first masters and then nodes. Pods are evacuated off of nodes and recreated on other running nodes before a node upgrade begins; this helps reduce downtime of user applications.

If you installed using the advanced installation and the ~/.config/openshift/installer.cfg.yml or inventory file that was used is available, you can perform an automated in-place upgrade. Alternatively, you can upgrade in-place manually.

The blue-green deployment upgrade method follows a similar flow to the in-place method: masters and etcd servers are still upgraded first, however a parallel environment is created for new nodes instead of upgrading them in-place.

This method allows administrators to switch traffic from the old set of nodes (e.g., the "blue" deployment) to the new set (e.g., the "green" deployment) after the new deployment has been verified. If a problem is detected, it is also then easy to rollback to the old deployment quickly.