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local volume

Using HwameiStor can run stateful applications very easily.

Here we use a MySQL application as an example.

Note

The MySQL Yaml file below is from Kubernetes official repo

View StorageClass

HwameiStor's Helm charts will install a StorageClass named hwameistor-storage-lvm-hdd by default, which can create local volumes.

Run the following command to open the YAML file. 

kubectl get sc hwameistor-storage-lvm-hdd -o yaml

Modify the following YAML file.

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: hwameistor-storage-lvm-hdd
parameters:
  convertible: "false"
  csi.storage.k8s.io/fstype:xfs
  poolClass: HDD
  poolType: REGULAR
  replicaNumber: "1"
  striped: "true"
  volumeKind: LVM
provisioner: lvm.hwameistor.io
reclaimPolicy: Delete
volumeBindingMode: WaitForFirstConsumer
allowVolumeExpansion: true

If this storageClass was not generated during installation, run the following yaml file to regenerate it:

kubectl apply -f examples/sc-local.yaml

Create StatefulSet

After HwameiStor and StorageClass are ready, one command can create MySQL container and its data volume:

kubectl apply -f sts-mysql_local.yaml

Note that volumeClaimTemplates uses storageClassName: hwameistor-storage-lvm-hdd:

spec:
  volumeClaimTemplates:
  - metadata:
      name: data
      labels:
        app: sts-mysql-local
        app.kubernetes.io/name: sts-mysql-local
    spec:
      storageClassName: hwameistor-storage-lvm-hdd
      accessModes: ["ReadWriteOnce"]
      resources:
        requests:
          storage: 1Gi

and schedulerName: hwameistor-scheduler:

spec:
  template:
    spec:
      schedulerName: hwameistor-scheduler

View MySQL container and PVC/PV

In this example, the MySQL container is scheduled to node k8s-worker-3.

$ kubectl get po -l app=sts-mysql-local -o wide
NAME READY STATUS RESTARTS AGE IP NODE
sts-mysql-local-0 2/2 Running 0 3m08s 10.1.15.154 k8s-worker-3

$ kubectl get pvc -l app=sts-mysql-local
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGE CLASS AGE VOLUME MODES
data-sts-mysql-local-0 Bound pvc-accf1ddd-6f47-4275-b520-dc317c90f80b 1Gi RWO hwameistor-storage-lvm-hdd 3m Filesystem

View the LocalVolume object

By viewing LocalVolume(LV) with the same name as PV, you can see that the local volume is created on the node k8s-worker-3:

$ kubectl get lv pvc-accf1ddd-6f47-4275-b520-dc317c90f80b

NAME POOL REPLICAS CAPACITY ACCESSIBILITY STATE RESOURCE PUBLISHED AGE
pvc-accf1ddd-6f47-4275-b520-dc317c90f80b LocalStorage_PoolHDD 1 1073741824 Ready-1 k8s-worker-3 3m

[Optional] Scale the MySQL application into a three-node cluster

HwameiStor supports the horizontal expansion of StatefulSet. StatefulSet container will mount an independent local volume:

$ kubectl scale sts/sts-mysql-local --replicas=3

$ kubectl get po -l app=sts-mysql-local -o wide
NAME READY STATUS RESTARTS AGE IP NODE
sts-mysql-local-0 2/2 Running 0 4h38m 10.1.15.154 k8s-worker-3
sts-mysql-local-1 2/2 Running 0 19m 10.1.57.44 k8s-worker-2
sts-mysql-local-2 0/2 Init:0/2 0 14s 10.1.42.237 k8s-worker-1

$ kubectl get pvc -l app=sts-mysql-local -o wide
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGE CLASS AGE VOLUME MODES
data-sts-mysql-local-0 Bound pvc-accf1ddd-6f47-4275-b520-dc317c90f80b 1Gi RWO hwameistor-storage-lvm-hdd 3m07s Filesystem
data-sts-mysql-local-1 Bound pvc-a4f8b067-9c1d-450f-aff4-5807d61f5d88 1Gi RWO hwameistor-storage-lvm-hdd 2m18s Filesystem
data-sts-mysql-local-2 Bound pvc-47ee308d-77da-40ec-b06e-4f51499520c1 1Gi RWO hwameistor-storage-lvm-hdd 2m18s Filesystem

$ kubectl get lv
NAME POOL REPLICAS CAPACITY ACCESSIBILITY STATE RESOURCE PUBLISHED AGE
pvc-47ee308d-77da-40ec-b06e-4f51499520c1 LocalStorage_PoolHDD 1 1073741824 Ready-1 k8s-worker-1 2m50s
pvc-a4f8b067-9c1d-450f-aff4-5807d61f5d88 LocalStorage_PoolHDD 1 1073741824 Ready-1 k8s-worker-2 2m50s
pvc-accf1ddd-6f47-4275-b520-dc317c90f80b LocalStorage_PoolHDD 1 1073741824 Ready-1 k8s-worker-3 3m40s

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