Use LVM to dynamically create local volumes - Container Service for Kubernetes

Container Service for Kubernetes (ACK) Edge Pro clusters allow you to use Logical Volume Manager (LVM) to manage local storage. LVM can automatically manage the lifecycle of logical volumes and schedule volumes based on the storage capacity of nodes. To use LVM to manage local storage as persistent volumes (PVs) and persistent volume claims (PVCs), you need only to define the topological relationship of local disks on the nodes. This topic describes how to use local LVM to manage local storage in an ACK Edge Pro cluster.

Prerequisites

Local disks are available on cluster nodes.
The TCP 1736 port of the node where the storage is deployed can be accessed from the cloud node.

The node-resource-manager, csi-plugin, and csi-provisioner components are installed.

Log on to the ACK console. In the left-side navigation pane, click Clusters.
On the Clusters page, click the name of the cluster that you want to manage and choose Operations > Add-ons in the left-side navigation pane.
On the Add-ons page, click the Storage tab, find the node-resource-manager, csi-plugin, and csi-provisioner components, and then click Install.
In the dialog box that appears, click OK.

Configure the VolumeGroup

Note

To ensure data security, the components do not delete VolumeGroups or physical volumes. Before you can redefine a VolumeGroup, you must delete the existing VolumeGroup.

Use the following YAML template to configure a ConfigMap that defines the topology for the VolumeGroup:

apiVersion: v1
kind: ConfigMap
metadata:
  name: node-resource-topo
  namespace: kube-system
data:
  volumegroup: |-
    volumegroup:
    - name: volumegroup1
      key: kubernetes.io/storagetype
      operator: In
      value: lvm
      topology:
        type: device
        devices:
        - /dev/sdb1
        - /dev/sdb2
        - /dev/sdc

The following table describes the parameters.

Parameter	Description
name	The name of the VolumeGroup.
key	Specifies the key that is used to match the key of the label on the nodes.
operator	Specifies the `operator that is used in the label selector`. Valid values: In: A match is found only if the value of the `value` parameter is the same as the `value` of the node label that has the specified key. NotIn: A match is found only if the value of the `value` parameter is different from the `value` of the node label that has the specified key. Exists: A match is found when the node has a label that has the specified key. DoesNotExist: A match is found when the node does not have a label that has the specified key.
value	Specifies the value that is used to match the `value` of the label that has the specified key.
topology	Specifies the topology of devices on the node. `topology.devices` specifies the paths of local disks on the node. The specified disks are added to the VolumeGroup.

Add labels to the nodes.
- Add a custom label to storage nodes based on the label that is specified in Step 1. This allows you to select nodes that meet the topological requirements. The label that is specified in Step 1 is as follows: kubernetes.io/storagetype=lvm.
- Add thealibabacloud.com/edge-enable-localstorage='true' label to a storage node so that the pod of the local storage management component can be scheduled to the node.
The node-resource-manager component on the node automatically creates a physical volume based on the preceding configurations and adds the physical volume to the VolumeGroup.

Use LVM to manage local storage

Use the following YAML file to define a PVC that specifies the StorageClass. Run the kubectl apply -f ****.yaml command to create the PVC. One PVC corresponds to one logical volume on the node. After the pod is created, the logical volume is mounted on the pod.

Note

In this example, the default storageClassName is csi-local-lvm.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: lvm-pvc-test
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 50Mi
  storageClassName: csi-local-lvm

---
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    k8s-app: local-test
  name: local-test
  namespace: default
spec:
  replicas: 1
  selector:
    matchLabels:
      k8s-app: local-test
  template:
    metadata:
      labels:
        k8s-app: local-test
    spec:
      hostNetwork: true
      containers:
      - image: nginx:1.15.7-alpine
        imagePullPolicy: IfNotPresent
        name: nginx
        resources: {}
        volumeMounts:
          - name: local-pvc
            mountPath: /data
      dnsPolicy: ClusterFirst
      restartPolicy: Always
      tolerations:
      - operator: Exists
      nodeSelector:
        alibabacloud.com/is-edge-worker: "true"
      volumes:
      - name: local-pvc
        persistentVolumeClaim: 
          claimName: lvm-pvc-test

Run the following command to check whether the logical volume is mounted:

kubectl exec -it local-test-564dfcf6dc-qhfsf sh
/ # ls /data

Expected output:

lost+found

The output indicates that the logical volume is mounted to the pod.