Practice Test - OS Upgrades

Solutions to practice test - OS Upgrades

Let us explore the environment first. How many nodes do you see in the cluster?
```
$ kubectl get nodes
```
How many applications do you see hosted on the cluster?
```
$ kubectl get deploy
```
Run the command 'kubectl get pods -o wide' and get the list of nodes the pods are placed on
```
$ kubectl get pods -o wide
```
Run the command kubectl drain node01 --ignore-daemonsets
```
$ kubectl drain node01 --ignore-daemonsets
```
Run the command 'kubectl get pods -o wide' and get the list of nodes the pods are placed on
```
$ kubectl get pods -o wide
```
Run the command kubectl uncordon node01
```
$ kubectl uncordon node01
```
Run the command kubectl get pods -o wide
```
$ kubectl get pods -o wide
```

Why are there no pods on node01?

Only when new pods are created they will be scheduled

Use the command kubectl describe node master and look under taint section to check if it has any taints.
```
$ kubectl describe node master
```
Run the command kubectl drain node02 --ignore-daemonsets
```
$ kubectl drain node02 --ignore-daemonsets
```

Check the applications hosted on the node02.

node02 has a pod not part of a replicaset

$ kubectl get pods -o wide

What would happen to hr-app if node02 is drained forcefully?

$ kubectl drain node02 --ignore-daemonsets --force

hr-app will be lost forever

Run the command kubectl drain node02 --ignore-daemonsets --force
```
$ kubectl drain node02 --ignore-daemonsets --force
```
Run the command kubectl cordon node03
```
$ kubectl cordon node03
```

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