Use Local Storage

Last Updated：2021-04-27

EmptyDir

Overview

The emptyDir type Volume is created when the Pod is allocated to the Node. Kubernetes will automatically assign a directory on the Node. Therefore, there is no need to specify the corresponding directory file on the host Node. The initial content of this directory is empty.

When the Pod is removed from the Node, the data in emptyDir will be deleted permanently.

Create a Pod using kubectl create -f testemptyDir.yaml. This Pod uses EmptyDir. The testemptyDir.yaml is as follows:

apiVersion: v1
kind: Pod
metadata:
  name: test-ed
spec:
  containers:
  - image: nginx
    name: test-container
    volumeMounts:
    - mountPath: /test
      name: cache-volume
  volumes:
  - name: cache-volume
    emptyDir: {}

View the details of the created Pod:

$ kubectl describe pod test-ed

Enter the Pod to view the mounting effect:

$ kubectl exec -it test-ed -c test-container /bin/sh

HostPath

Overview

The HostPath type maps files or directories in the Node file system to the Pod. When using the HostPath type of storage volume, you can also set the type field. The supported types include file, directory, File, Socket, CharDevice, and BlockDevice.

Create a Pod using kubectl create -f testhostPath.yaml. The Pod uses HostPath. The testhostPathr.yaml is as follows:

apiVersion: v1
kind: Pod
metadata:
  name: test-hp
spec:
  containers:
  - image: nginx
    name: test-container
    volumeMounts:
    - mountPath: /test-pd
      name: test-volume
  volumes:
  - name: test-volume
    hostPath:
      #directory location on host
      path: /data

Local Volume

Overview

Local Volume allows you to use Node's local disks, partitions, or directories as persistent storage. Local Volume is suitable for data caching so that aplications can access data nearby and process it quickly. Also, it is suitable for distributed storage systems such as distributed database Cassandra and distributed file system ceph/gluster.

The applicability of some current Kubernetes to Local PV is as follows:

Kubernetes v1.7： Officially introduced Local PV;
Kubernetes v1.10： Local PV enters Beta;
Kubernetes v1.14： Local PV enters GA

Create storage class

The content of kubectl create -f local-volume.yaml，local-volume.yaml is as follows:

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

Where, WaitForFirstConsumer indicates that you do not need to bind PV to PVC immediately, but bind it until a Pod needs to use PVC.

Create PV Statically

Through kubectl create -f local-volume-pv.yaml, statically create a 5GiB PV. The PV uses the node's /data/volume directory. You need to create the directory manually.

The content of local-volume-pv.yaml is as follows:

apiVersion: v1
kind: PersistentVolume
metadata:
  name: example-local-pv
spec:
  capacity:
    storage: 5Gi
  accessModes:
  - ReadWriteOnce
  persistentVolumeReclaimPolicy: Retain
  storageClassName: local-volume
  local:
    path: /data/volume
  nodeAffinity:
    required:
      nodeSelectorTerms:
      - matchExpressions:
        - key: kubernetes.io/hostname
          operator: In
          values:
          - HOSTNAME

Get node_name through kubectl get nodes and replace the HOSTNAME field above.

$ kubectl get pv example-local-pv
$ kubectl get pv
NAME                                      CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                          STORAGECLASS      REASON   AGE
example-local-pv                          5Gi        RWO            Retain           Bound    default/myclaim                local-volume               5s

Use Local Volume PV

Create a PVC associated with the local-volume and then a pod to use the PVC, kubectl create -f local-volume-pvc.yaml .

The content of ocal-volume-pvc.yaml is as follows:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mypvc
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 5Gi
  storageClassName: local-volume
---
kind: Pod
apiVersion: v1
metadata:
  name: mypod
spec:
  containers:
    - name: myfrontend
      image: nginx
      volumeMounts:
      - mountPath: "/usr/share/nginx/html"
        name: mypd
  volumes:
    - name: mypd
      persistentVolumeClaim:
        claimName: mypvc

View the created pv, pvc, and pod.

$ kubectl get pv
NAME                    CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                          STORAGECLASS      REASON   AGE
example-local-pv        5Gi        RWO            Retain           Bound    default/mypvc                  local-volume               5s
$ kubectl get pvc
NAME                   STATUS   VOLUME                                    CAPACITY   ACCESS MODES   STORAGECLASS      AGE
mypvc                  Bound    example-local-pv                          5Gi        RWO            local-volume      4m20s
$ kubectl get pods
NAME                             READY   STATUS    RESTARTS   AGE
mypod                            1/1     Running   0          4m28s

Write content to the local /data/volume and use curl to check whether the write is successful.

$ echo "hello world" > /data/volume/index.html
$ curl 172.19.4.63
#Replace it with the ip of your pod.
hello world

During deletion, delete the created pod and then pvc and pv in turn.

Overview

Use Cloud Disk Storage (CDS)

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Cloud Container Engine

Use Local Storage

EmptyDir

Overview

HostPath

Overview

Local Volume

Overview

Create PV Statically

Use Local Volume PV