Here is a step-by-step guide with actual commands to upgrade a Kubernetes cluster to a specific version:
- Verify the current version of your cluster:
kubectl version
- Determine the desired version you want to upgrade to:
Check the list of available versions in the official Kubernetes release history.
- Create a backup of your cluster:
It is important to have a backup of your cluster before performing any upgrade. You can create a backup of the cluster by backing up etcd data and taking snapshots of your nodes.
- Put your cluster in maintenance mode:
Put your cluster in maintenance mode to avoid new deployments and upgrades during the upgrade process. You can do this by draining nodes and/or cordoning them. For example, to drain a node:
kubectl drain <node-name> --ignore-daemonsets
To cordon a node:
kubectl cordon <node-name>
- Upgrade the control plane components:
The control plane components, such as the API server, controller manager, and scheduler, should be upgraded first. You can upgrade these components using the kubeadm tool. For example:
kubeadm upgrade plan --version=<version> kubeadm upgrade apply --version=<version>
- Upgrade the worker nodes:
Once the control plane components are upgraded, you can upgrade the worker nodes. This can be done using the kubeadm tool or by rolling updates with a tool like kubectl. For example, to upgrade worker nodes using kubeadm:
kubeadm upgrade node
- Verify the upgraded version:
Verify that the cluster has been successfully upgraded to the desired version by checking the version of each component.
kubectl version
- Exit maintenance mode:
If you put your cluster in maintenance mode, remember to exit maintenance mode after the upgrade is complete. For example, to uncordon a node:
kubectl uncordon <node-name>
Note: The exact steps may vary depending on the specific version and upgrade method you are using. Before performing an upgrade, it is always recommended to review the official Kubernetes documentation and follow best practices.