kubernetes 学習 PersistentVolume

PersistenceVolume 使うべからず？いままで避けていたが機会が巡ってきたのでやってみる。

persistent-volumes

https://kubernetes.io/docs/concepts/storage/persistent-volumes/

kubernetes.io

• StorageClass: ストレージの種類を示すオブジェクト
• PersistentVolume(PV): 永続化ボリュームについてのオブジェクト
• PersistentVolumeClaim(PVC): 永続化ボリュームの利用請求をするオブジェクト

PersistentVolume, PersistentVolumeClaim を作成

my-pv.yaml, my-pvc.yamlを作成

my-pv.yaml

apiVersion: v1
kind: PersistentVolume
metadata:
  name: my-pv
  labels:
    type: local
spec:
  storageClassName: manual
  capacity:
    storage: 5Gi
  accessModes:
    - ReadWriteOnce
  hostPath:
    path: "/mnt/data"

my-pvc.yaml

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: my-pvc
spec:
  accessModes:
    - ReadWriteOnce
  volumeMode: Filesystem
  resources:
    requests:
      storage: 5Gi
  storageClassName: manual

apply し確認

$ kubectl apply -f my-pv.yaml
persistentvolume/my-pv created
$ kubectl apply -f my-pvc.yaml
persistentvolumeclaim/my-pvc created
$ kubectl get pv,pvc
NAME                     CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM            STORAGECLASS   REASON   AGE
persistentvolume/my-pv   5Gi        RWO            Retain           Bound    default/my-pvc   manual                  12s

NAME                           STATUS   VOLUME   CAPACITY   ACCESS MODES   STORAGECLASS   AGE
persistentvolumeclaim/my-pvc   Bound    my-pv    5Gi        RWO            manual         9s

pod へマウントして試す

my-pod.yaml

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
  - image: alpine
    name: alpine
    command: ["tail", "-f", "/dev/null"]
    volumeMounts:
    - name: claim-volume
      mountPath: /data
  volumes:
  - name: claim-volume
    persistentVolumeClaim:
      claimName: my-pvc
  terminationGracePeriodSeconds: 0

apply して df。/data がいる。touch でファイル作成

$ kubectl apply -f my-pod.yaml
pod/my-pod created
$ kubectl exec my-pod -- df /data
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/vda9             17897500   2210592  14907276  13% /data
$ kubectl exec my-pod -- touch /data/asdf

node22に /mnt/data/asdf ができていた

$ ls -al /mnt/data/
total 20
drwxr-xr-x. 2 root root 4096 Aug 14 20:31 .
drwxr-xr-x. 3 root root 4096 Aug 14 20:22 ..
-rw-r--r--. 1 root root    0 Aug 14 20:31 asdf

お掃除

$ kubectl delete -f my-pod.yaml
pod "my-pod" deleted
$ kubectl delete -f my-pvc.yaml
persistentvolumeclaim "my-pvc" deleted
$ kubectl delete -f my-pv.yaml
persistentvolume "my-pv" deleted