# Cluster Upgrade

## Versions

`vMajor.Minor.Patch` semantic versioning

K8S compatibility is as follow : current and n-2 version are supported.

**Always upgrade minor to minor releases**.

## kubeadm

### Check latest/upgradable version

```shell
kubeadm upgrade plan
```

## Master node upgrade

### Drain and mark it at Unschedulable

```shell
kubectl drain master
```

`kubectl get nodes` to verify that master node is unschedulable

### kubeadm update

```shell
apt install kubeadm=X.Y.Z-00
```

`kubeadm version` to ensure version number

### Node update

```shell
kubeadm upgrade apply vX.Y.Z
```

`kubectl version` to validate

### Update kubelet

```shell
apt install kubelet=X.Y.Z-00
```

`kubectl get nodes` to validate

### Mark master node as schedulable

```shell
kubectl uncordon master
```

## Worker nodes upgrade

Repeat the same actions done on master for each worker node

🎉