[CKA][실습] 7. Storage

Practice Test - Persistent Volume Claims

hostPath

$ alias k=kubectl
$ k edit po webapp
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: "2023-06-12T10:46:35Z"
  name: webapp
  namespace: default
  resourceVersion: "674"
  uid: 382c1ae3-0641-4107-9105-eb1ec05b028e
spec:
  containers:
  - env:
    - name: LOG_HANDLERS
      value: file
    image: kodekloud/event-simulator
    imagePullPolicy: Always
    name: event-simulator
    resources: {}
    terminationMessagePath: /dev/termination-log
    terminationMessagePolicy: File
    volumeMounts:
    - mountPath: /var/run/secrets/kubernetes.io/serviceaccount
      name: kube-api-access-d299x
      readOnly: true
    - mountPath: /log
      name: host-path-volume
  ...
  volumes:
  - name: host-path-volume
    hostPath:
      path: /var/log/webapp
      type: Directory
  ...
$ k replace -f /tmp/kubectl-edit-430428576.yaml --force

PV & PVC

apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-log
spec:
  capacity:
    storage: 100Mi
  accessModes:
    - ReadWriteMany
  persistentVolumeReclaimPolicy: Retain
  hostPath:
    path: "/pv/log"

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: claim-log-1
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 50Mi

상태 확인

$  k get pv,pvc
NAME                      CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM   STORAGECLASS   REASON   AGE
persistentvolume/pv-log   100Mi      RWX            Retain           Available                                   2m52s

NAME                                STATUS    VOLUME   CAPACITY   ACCESS MODES   STORAGECLASS   AGE
persistentvolumeclaim/claim-log-1   Pending

pvc 수정

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: claim-log-1
spec:
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 50Mi

$ k replace -f pvc.yaml --force
persistentvolumeclaim "claim-log-1" deleted
persistentvolumeclaim/claim-log-1 replaced
$ k get pv,pvc
NAME                      CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                 STORAGECLASS   REASON   AGE
persistentvolume/pv-log   100Mi      RWX            Retain           Bound    default/claim-log-1                           4m12s

NAME                                STATUS   VOLUME   CAPACITY   ACCESS MODES   STORAGECLASS   AGE
persistentvolumeclaim/claim-log-1   Bound    pv-log   100Mi      RWX

pod 수정(pvc 연결)

$ k edit po webapp
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: "2023-06-12T10:57:15Z"
  name: webapp
  namespace: default
  resourceVersion: "1514"
  uid: 02b2de96-2c8c-4681-8b22-d445196c4828
spec:
  containers:
  - env:
    - name: LOG_HANDLERS
      value: file
    image: kodekloud/event-simulator
    imagePullPolicy: Always
    name: event-simulator
    resources: {}
    terminationMessagePath: /dev/termination-log
    terminationMessagePolicy: File
    volumeMounts:
    - mountPath: /var/run/secrets/kubernetes.io/serviceaccount
      name: kube-api-access-d299x
      readOnly: true
    - mountPath: /log
      name: pvc-volume
 ...
  volumes:
  - name: pvc-volume
    persistentVolumeClaim:
      claimName: claim-log-1
 ...
 $ k replace -f /tmp/kubectl-edit-2965563831.yaml --force

---

Practice Test - Storage Class

$ k get sc
NAME                        PROVISIONER                     RECLAIMPOLICY   VOLUMEBINDINGMODE      ALLOWVOLUMEEXPANSION   AGE
local-path (default)        rancher.io/local-path           Delete          WaitForFirstConsumer   false                  7m23s
local-storage               kubernetes.io/no-provisioner    Delete          WaitForFirstConsumer   false                  4s
portworx-io-priority-high   kubernetes.io/portworx-volume   Delete          Immediate              false                  4s
$ k get pv
NAME       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM   STORAGECLASS    REASON   AGE
local-pv   500Mi      RWO            Retain           Available           local-storage            3m18s

PVC 생성

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: local-pvc
spec:
  accessModes:
    - ReadWriteOnce
  volumeMode: Filesystem
  resources:
    requests:
      storage: 500Mi
  storageClassName: local-storage

$ k describe pvc local-pvc
Name:          local-pvc
Namespace:     default
StorageClass:  local-storage
Status:        Pending
Volume:        
Labels:        <none>
Annotations:   <none>
Finalizers:    [kubernetes.io/pvc-protection]
Capacity:      
Access Modes:  
VolumeMode:    Filesystem
Used By:       <none>
Events:
  Type    Reason                Age               From                         Message
  ----    ------                ----              ----                         -------
  Normal  WaitForFirstConsumer  6s (x3 over 33s)  persistentvolume-controller  waiting for first consumer to be created before binding

Pod 생성

$ k run nginx --image=nginx:alpine --dry-run=client -o yaml > pod.yaml
$ vi pod.yaml
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: nginx
  name: nginx
spec:
  containers:
  - image: nginx:alpine
    name: nginx
    resources: {}
    volumeMounts:
      - mountPath: "/var/www/html"
        name: local-pv
  dnsPolicy: ClusterFirst
  restartPolicy: Always
  volumes:
    - name: local-pv
      persistentVolumeClaim:
        claimName: local-pvc
status: {}
$ k apply -f pod.yaml
$ k get po,pvc,pv
NAME        READY   STATUS    RESTARTS   AGE
pod/nginx   1/1     Running   0          50s

NAME                              STATUS   VOLUME     CAPACITY   ACCESS MODES   STORAGECLASS    AGE
persistentvolumeclaim/local-pvc   Bound    local-pv   500Mi      RWO            local-storage   8m9s

NAME                        CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM               STORAGECLASS    REASON   AGE
persistentvolume/local-pv   500Mi      RWO            Retain           Bound    default/local-pvc   local-storage            13m

Storage Class 생성

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: delayed-volume-sc
provisioner: kubernetes.io/no-provisioner
volumeBindingMode: WaitForFirstConsumer

참고) https://kubernetes.io/docs/concepts/storage/storage-classes/#local