what are ack cluster memory volumes - Container Service for Kubernetes

Container Service for Kubernetes (ACK) provides temporary memory volumes. These volumes provide high-performance, local temporary storage for your applications.

Background information

Memory volumes provide temporary storage, but data is lost when a pod restarts.
This type of local storage is suitable for high-speed caching scenarios.

Deploy the plugin

The memory Container Storage Interface (CSI) plugin has two components: the Plugin, which mounts memory volumes, and the Provisioner, which creates memory volumes.

Note

This feature is supported only in ACK clusters that run Kubernetes 1.18 or earlier.

Deploy the CSI Memory Plugin

apiVersion: storage.k8s.io/v1beta1
kind: CSIDriver
metadata:
  name: memplugin.csi.alibabacloud.com
spec:
  attachRequired: false
  podInfoOnMount: true
---
kind: DaemonSet
apiVersion: apps/v1
metadata:
  name: csi-mem-plugin
  namespace: kube-system
spec:
  selector:
    matchLabels:
      app: csi-mem-plugin
  template:
    metadata:
      labels:
        app: csi-mem-plugin
    spec:
      tolerations:
        - operator: Exists
      serviceAccount: admin
      priorityClassName: system-node-critical
      hostNetwork: true
      hostPID: true
      containers:
        - name: driver-registrar
          image: registry.cn-hangzhou.aliyuncs.com/acs/csi-node-driver-registrar:v1.1.0
          imagePullPolicy: Always
          args:
            - "--v=5"
            - "--csi-address=/csi/csi.sock"
            - "--kubelet-registration-path=/var/lib/kubelet/plugins/memplugin.csi.alibabacloud.com/csi.sock"
          env:
            - name: KUBE_NODE_NAME
              valueFrom:
                fieldRef:
                  apiVersion: v1
                  fieldPath: spec.nodeName
          volumeMounts:
            - name: plugin-dir
              mountPath: /csi
            - name: registration-dir
              mountPath: /registration
        - name: csi-memplugin
          securityContext:
            privileged: true
            capabilities:
              add: ["SYS_ADMIN"]
            allowPrivilegeEscalation: true
          image: registry.cn-hangzhou.aliyuncs.com/acs/csi-plugin:v1.14.8.41-9efe2ede-aliyun
          imagePullPolicy: "Always"
          args :
            - "--endpoint=$(CSI_ENDPOINT)"
            - "--v=5"
            - "--nodeid=$(KUBE_NODE_NAME)"
            - "--driver=memplugin.csi.alibabacloud.com"
          env:
            - name: KUBE_NODE_NAME
              valueFrom:
                fieldRef:
                  apiVersion: v1
                  fieldPath: spec.nodeName
            - name: CSI_ENDPOINT
              value: unix://var/lib/kubelet/plugins/memplugin.csi.alibabacloud.com/csi.sock
          volumeMounts:
            - name: pods-mount-dir
              mountPath: /var/lib/kubelet
              mountPropagation: "Bidirectional"
            - mountPath: /dev
              mountPropagation: "HostToContainer"
              name: host-dev
            - mountPath: /var/log/
              name: host-log
      volumes:
        - name: plugin-dir
          hostPath:
            path: /var/lib/kubelet/plugins/memplugin.csi.alibabacloud.com
            type: DirectoryOrCreate
        - name: registration-dir
          hostPath:
            path: /var/lib/kubelet/plugins_registry
            type: DirectoryOrCreate
        - name: pods-mount-dir
          hostPath:
            path: /var/lib/kubelet
            type: Directory
        - name: host-dev
          hostPath:
            path: /dev
        - name: host-log
          hostPath:
            path: /var/log/
  updateStrategy:
    rollingUpdate:
      maxUnavailable: 10%
    type: RollingUpdate

Deploy the CSI Memory Provisioner

kind: Deployment
apiVersion: apps/v1
metadata:
  name: csi-memprovisioner
  namespace: kube-system
spec:
  selector:
    matchLabels:
      app: csi-memprovisioner
  replicas: 2
  template:
    metadata:
      labels:
        app: csi-memprovisioner
    spec:
      tolerations:
      - operator: "Exists"
      affinity:
        nodeAffinity:
          preferredDuringSchedulingIgnoredDuringExecution:
          - weight: 1
            preference:
              matchExpressions:
              - key: node-role.kubernetes.io/master
                operator: Exists
      priorityClassName: system-node-critical
      serviceAccount: admin
      hostNetwork: true
      containers:
        - name: csi-provisioner
          image: registry.cn-hangzhou.aliyuncs.com/acs/csi-provisioner:v1.4.0-aliyun
          args:
            - "--provisioner=memplugin.csi.alibabacloud.com"
            - "--csi-address=$(ADDRESS)"
            - "--feature-gates=Topology=True"
            - "--volume-name-prefix=mem"
            - "--strict-topology=true"
            - "--timeout=150s"
            - "--enable-leader-election=true"
            - "--leader-election-type=leases"
            - "--retry-interval-start=500ms"
            - "--v=5"
          env:
            - name: ADDRESS
              value: /var/lib/kubelet/plugins/memplugin.csi.alibabacloud.com/csi.sock
          imagePullPolicy: "Always"
          volumeMounts:
            - name: socket-dir
              mountPath: /var/lib/kubelet/plugins/memplugin.csi.alibabacloud.com
      volumes:
        - name: socket-dir
          hostPath:
            path: /var/lib/kubelet/plugins/memplugin.csi.alibabacloud.com
            type: DirectoryOrCreate

Example: Use a memory volume

Use the following template to deploy a StorageClass.

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
   name: csi-mem
provisioner: memplugin.csi.alibabacloud.com
reclaimPolicy: Delete

Use the following template to create a persistent volume claim (PVC) and an application.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mem-pvc
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 2Gi
  storageClassName: csi-mem
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: deployment-mem
  labels:
    app: nginx
spec:
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: anolis-registry.cn-zhangjiakou.cr.aliyuncs.com/openanolis/nginx:1.14.1-8.6
        command: ["sh", "-c"]
        args: ["sleep 10000"]
        volumeMounts:
          - name: mem-pvc
            mountPath: "/data"
      volumes:
        - name: mem-pvc
          persistentVolumeClaim:
            claimName: mem-pvc