Working with PV & PVC in Kubernetes

Using Google Cloud, create a persistent disk in the same region as your cluster:
```
gcloud compute disks create --size=1GiB --zone=us-central1-a mongodb
```

The YAML for a pod that will use persistent disk:

apiVersion: v1
kind: Pod
metadata:
  name: mongodb 
spec:
  volumes:
  - name: mongodb-data
    gcePersistentDisk:
      pdName: mongodb
      fsType: ext4
  containers:
  - image: mongo
    name: mongodb
    volumeMounts:
    - name: mongodb-data
      mountPath: /data/db
    ports:
    - containerPort: 27017
      protocol: TCP

Create the pod with disk attached and mounted:
```
kubectl apply -f mongodb-pod.yaml
```
See which node the pod landed on:
```
kubectl get pods -o wide
```
Connect to the mongodb shell:
```
kubectl exec -it mongodb mongo
```
Switch to the mystore database in the mongodb shell:
```
use mystore
```
Create a JSON document to insert into the database:
```
db.foo.insert({name:'foo'})
```
View the document you just created:
```
db.foo.find()
```
Exit from the mongodb shell:
```
exit 
```
Delete the pod:
```
kubectl delete pod mongodb
```
Create a new pod with the same attached disk:
```
kubectl apply -f mongodb-pod.yaml
```
Check to see which node the pod landed on:
```
kubectl get pods -o wide
```
Drain the node (if the pod is on the same node as before):
```
kubectl drain [node_name] --ignore-daemonsets
```
Once the pod is on a different node, access the mongodb shell again:
```
kubectl exec -it mongodb mongo
```
Access the mystore database again:
```
use mystore
```
Find the document you created from before:
```
db.foo.find()
```

The YAML for a PersistentVolume object in Kubernetes:

apiVersion: v1
kind: PersistentVolume
metadata:
  name: mongodb-pv
spec:
  capacity: 
    storage: 1Gi
  accessModes:
    - ReadWriteOnce
    - ReadOnlyMany
  persistentVolumeReclaimPolicy: Retain
  gcePersistentDisk:
    pdName: mongodb
    fsType: ext4

Create the Persistent Volume resource:

kubectl apply -f mongodb-persistentvolume.yaml

View our Persistent Volumes:
```
kubectl get persistentvolumes
```

Working with PV & PVC in Kubernetes

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