Thundercloud
Javascript

Persistent Storage for Google Kubernetes Engine

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1. Create PVs and PVCs

Connect to the lab GKE cluster

$export my_zone=us-central1-a
$export my_cluster=standard-cluster-1
$source <(kubectl completion bash)
$gcloud container clusters get-credentials $my_cluster --zone $my_zone


Fetching cluster endpoint and auth data.
kubeconfig entry generated for standard-cluster-1.

Create and apply a manifest with a PVC

pvc-demo.yaml

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: hello-web-disk
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 30Gi
$git clone https://github.com/GoogleCloudPlatform/training-data-analyst
$ln -s ~/training-data-analyst/courses/ak8s/v1.1 ~/ak8s
$cd ~/ak8s/Storage/

현재 PVC를 보여 준다

$$kubectl get persistentvolumeclaim

현재는 없ㅎ다. 

No resources found in default namespace.

PVC만든다.

kubectl apply -f pvc-demo.yaml

다시 조회

NAME           STATUS VOLUME        CAP   ACCESS MODES      CLASS   AGE
hello-web-disk Bound  pvc-8...34   30Gi            RWO   standard    5s

생겼다.

2. Mount and verify Google Cloud persistent disk PVCs in Pods

Mount the PVC to a Pod

pod-volume-demo.yaml

kind: Pod
apiVersion: v1
metadata:
  name: pvc-demo-pod
spec:
  containers:
    - name: frontend
      image: nginx
      volumeMounts:
      - mountPath: "/var/www/html"
        name: pvc-demo-volume
  volumes:
    - name: pvc-demo-volume
      persistentVolumeClaim:
        claimName: hello-web-disk

만든다.

$kubectl apply -f pod-volume-demo.yaml

만들어 졌다.

pod/pvc-demo-pod created

확인

$kubectl get pods


NAME           READY   STATUS    RESTARTS   AGE
pvc-demo-pod   1/1     Running   0          28s

셀세션 시작

kubectl exec -it pvc-demo-pod -- sh
echo Test webpage in a persistent volume!>/var/www/html/index.html
chmod +x /var/www/html/index.html
exet

Test the persistence of the PV

1. 지운다. pvc-demo-pod.

$kubectl delete pod pvc-demo-pod

pod "pvc-demo-pod" deleted

2. 확인 한다.

$kubectl get pods 지워졌다. 

No resources found in default namespace.

3. PVC를 확인

$kubectl get persistentvolumeclaim

NAME             STATUS   VOLUME                   CAPACITY   ACCESS MODES   STORAGECLASS   AGE
hello-web-disk   Bound    pvc-                     30Gi       RWO            standard       7m43s

4. pvc-demo-pod 재 패포

$kubectl apply -f pod-volume-demo.yaml
Output 

pod/pvc-demo-pod created

5. pvc-demoe-pod 쉘 접속

$kubectl exec -it pvc-demo-pod -- sh
접속되면 #으로 바뀐다. #cat /var/www/html/index.html

Output

Test webpage in a persistent volume!

빠져 나온다. #exit

image

3.Create StatefulSets with PVCs

이 작업에서는 StatefulSet에서 PVC를 사용합니다.
StatefulSet은 포드에 고유 식별자가 제공된다는 점을 제외하고는 배포와 같습니다.

Release the PVC

pvc-demo-pod 삭제

$kubectl delete pod pvc-demo-pod

지워졌졌음.

pod "pvc-demo-pod" deleted

확인
kubectl get pods 결과

No resources found in default namespace.

Create a StatefulSet

스테이플셋 생성 statefulset-demo.yaml

kind: Service
apiVersion: v1
metadata:
  name: statefulset-demo-service
spec:
  ports:
  - protocol: TCP
    port: 80
    targetPort: 9376
  type: LoadBalancer
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: statefulset-demo
spec:
  selector:
    matchLabels:
      app: MyApp
  serviceName: statefulset-demo-service
  replicas: 3
  updateStrategy:
    type: RollingUpdate
  template:
    metadata:
      labels:
        app: MyApp
    spec:
      containers:
      - name: stateful-set-container
        image: nginx
        ports:
        - containerPort: 80
          name: http
        volumeMounts:
        - name: hello-web-disk
          mountPath: "/var/www/html"
  volumeClaimTemplates:
  - metadata:
      name: hello-web-disk
    spec:
      accessModes: [ "ReadWriteOnce" ]
      resources:
        requests:
          storage: 30Gi

생성

$kubectl apply -f statefulset-demo.yaml

로드벨런싱 되는 서비스와, 30G 볼륨이 생성되었음. hello-web-disk /var/www/html 마운트 욈

service/statefulset-demo-service created
statefulset.apps/statefulset-demo created

Verify the connection of Pods in StatefulSets

StatefulSet에서 포드의 연결 확인

세부 정보 확인

$kubectl describe statefulset statefulset-demo
Output 

Name:               statefulset-demo
Namespace:          default
CreationTimestamp:  Sat, 05 Feb 2022 09:11:44 +0000
Selector:           app=MyApp
Labels:             <none>
Annotations:        <none>
Replicas:           3 desired | 3 total
Update Strategy:    RollingUpdate
Pods Status:        3 Running / 0 Waiting / 0 Succeeded / 0 Failed
Pod Template:
  Labels:  app=MyApp
  Containers:
   stateful-set-container:
    Image:        nginx
    Port:         80/TCP
    Host Port:    0/TCP
    Environment:  <none>
    Mounts:
      /var/www/html from hello-web-disk (rw)
  Volumes:  <none>
Volume Claims:
  Name:          hello-web-disk
  StorageClass:
  Labels:        <none>
  Annotations:   <none>
  Capacity:      30Gi
  Access Modes:  [ReadWriteOnce]
Events:
  Type    Reason            Age    From                    Message
  ----    ------            ----   ----                    -------
  Normal  SuccessfulCreate  2m52s  statefulset-controller  create Claim hello-web-disk-statefulset-demo-0 Pod statefulset-demo-0 in StatefulSet statefulset-demo success
  Normal  SuccessfulCreate  2m52s  statefulset-controller  create Pod statefulset-demo-0 in StatefulSet statefulset-demo successful
  Normal  SuccessfulCreate  2m38s  statefulset-controller  create Claim hello-web-disk-statefulset-demo-1 Pod statefulset-demo-1 in StatefulSet statefulset-demo success
  Normal  SuccessfulCreate  2m38s  statefulset-controller  create Pod statefulset-demo-1 in StatefulSet statefulset-demo successful
  Normal  SuccessfulCreate  2m24s  statefulset-controller  create Claim hello-web-disk-statefulset-demo-2 Pod statefulset-demo-2 in StatefulSet statefulset-demo success
  Normal  SuccessfulCreate  2m24s  statefulset-controller  create Pod statefulset-demo-2 in StatefulSet statefulset-demo successful

포드 리스트 확인

$keubectl get pods 

NAME                 READY   STATUS    RESTARTS   AGE
statefulset-demo-0   1/1     Running   0          4m14s
statefulset-demo-1   1/1     Running   0          4m
statefulset-demo-2   1/1     Running   0          3m46s

PVC 확인

$kubectl get pvc

NAME                                STATUS   VOLUME   CAPACITY   ACCESS MODES   STORAGECLASS   AGE
hello-web-disk                      Bound    pvc-80   30Gi       RWO            standard       20m
hello-web-disk-statefulset-demo-0   Bound    pvc-3a   30Gi       RWO            standard       5m4s
hello-web-disk-statefulset-demo-1   Bound    pvc-42   30Gi       RWO            standard       4m50s
hello-web-disk-statefulset-demo-2   Bound    pvc-4c   30Gi       RWO            standard       4m36s

스테이트풀 pvc 확인

$kubectl describe pvc hello-web-disk-statefulset-demo-0

4. Verify the persistence of Persistent Volume connections to Pods managed by StatefulSets

statefulset-demo-0 쉘 접속

$kubectl exec -it statefulset-demo-0 -- sh

# echo Test webpage in a persistent volume!>/var/www/html/index.html
chmod +x /var/www/html/index.html#
#
# cat /var/www/html/index.html
Test webpage in a persistent volume!
#
# exit
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