devops-exercises/exercises/kubernetes/solutions/replicaset_03_solution.md
2021-09-27 00:34:59 +03:00

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## ReplicaSet 03 - Solution
1. Create a ReplicaSet with 2 replicas. Make sure the label used for the selector and in the Pods is "type=web"
```
cat >> rs.yaml <<EOL
apiVersion: apps/v1
kind: ReplicaSet
metadata:
name: web
labels:
app: somewebapp
type: web
spec:
replicas: 2
selector:
matchLabels:
type: web
template:
metadata:
labels:
type: web
spec:
containers:
- name: httpd
image: registry.redhat.io/rhscl/httpd-24-rhel7
EOL
kubectl apply -f rs.yaml
```
2. Verify a ReplicaSet was created and there are 2 replicas
```
kubectl get rs
# OR a more specific way: kubectl get -f rs.yaml
```
3. List the Pods running and save the output somewhere
```
kubectl get po > running_pods.txt
```
4. Remove the label (type=web) from one of the Pods created by the ReplicaSet
```
kubectl label pod <POD_NAME> type-
```
5. List the Pods running. Are there more Pods running after removing the label? Why?
```
Yes, there is an additional Pod running because once the label (used as a matching selector) was removed, the Pod became independant meaning, it's not controlled by the ReplicaSet anymore and the ReplicaSet was missing replicas based on its definition so, it created a new Pod.
```
6. Verify the ReplicaSet indeed created a new Pod
```
kubectl describe rs web
```