Kubernetes uses the StorageClass to dynamically generate NFS-BASED PVS

Small knowledge, big challenge! This article is participating in the creation activity of “Essential Tips for Programmers”.

This article has participated in the “Digitalstar Project” and won a creative gift package to challenge the creative incentive money.

What is a StorageClass

The StorageClass object defines the following two parts:

• 1: PV attribute. For example, storage type,Volume size, etc
• 2: Create the storage plug-in needed for this PV

With these two pieces of information, Kubernetes can find a StorageClass based on the PVC submitted by the user, and then Kubernetes will call the storage plug-in declared by the StorageClass to create the required PV.

However, it is very simple to use, you just need to write YAML file according to your needs, and then use kubectl create command to execute.

process

1. Create an available NFS Serve
2. Create a Service Account. This is used to control the permission to run NFS Provisioner in the K8S cluster
3. Create the StorageClass. Be responsible for setting up the PVC and calling the NFS provisioner to do the required work, and let the PV and PVC establish management
4. Create NFS provisioner. It provides two functions, one is to create a volume of mount points in the NFS shared directory, and the other is to create a PV and associate the PV with the NFS mount point

Create StorageClass

Example Creating an NFS share service

[root@nfs nfsdata]# yum install -y nfs-utils
[root@nfs nfsdata]# mkdir /nfsdata
[root@nfs nfsdata]# chmod 755 /nfsdata
[root@nfs nfsdata]# chown nfsnobody:nfsnobody /nfsdata/
[root@nfs nfsdata]# echo "/nfsdata *(rw,sync,all_squash)" > /etc/exports
[root@nfs nfsdata]# systemctl enable nfs
[root@nfs nfsdata]# systemctl start nfs
[root@nfs nfsdata]# exportfs -rv
exporting *:/nfsdata
Copy the code

Create an account and related rights

nfs-rbac.yaml

apiVersion: v1
kind: ServiceAccount
metadata:
  name: nfs-provisioner
 # replace with namespace where provisioner is deployed
  namespace: nfs-provisioner Set a namespace based on the actual environment
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: nfs-provisioner-runner
rules:
- apiGroups: [""]
  resources: ["persistentvolumes"]
  verbs: ["get"."list"."watch"."create"."delete"]
- apiGroups: [""]
  resources: ["persistentvolumeclaims"]
  verbs: ["get"."list"."watch"."update"]
- apiGroups: ["storage.k8s.io"]
  resources: ["storageclasses"]
  verbs: ["get"."list"."watch"]
- apiGroups: [""]
  resources: ["events"]
  verbs: ["create"."update"."patch"]
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: run-nfs-provisioner
subjects:
- kind: ServiceAccount
  name: nfs-provisioner
   # replace with namespace where provisioner is deployed
  namespace: nfs-provisioner
roleRef:
kind: ClusterRole
name: nfs-provisioner-runner
apiGroup: rbac.authorization.k8s.io
---
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: leader-locking-nfs-provisioner
  # replace with namespace where provisioner is deployed
  namespace: nfs-provisioner
rules:
- apiGroups: [""]
  resources: ["endpoints"]
  verbs: ["get"."list"."watch"."create"."update"."patch"]
---
kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: leader-locking-nfs-provisioner
subjects:
- kind: ServiceAccount
  name: nfs-provisioner
   # replace with namespace where provisioner is deployed
  namespace: nfs-provisioner
roleRef:
kind: Role
name: leader-locking-nfs-provisioner
apiGroup: rbac.authorization.k8s.io
Copy the code

Create an NFS resource StorageClass

nfs-storageclass.yaml

kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: nfs
provisioner: example.com/nfs The name here must be the same as the environment variable PROVISIONER_NAME in the provisioner configuration file
Copy the code

Create NFS Provisioner Deployment

nfs-deployment.yaml

kind: Deployment
apiVersion: apps/v1
metadata:
  name: nfs-provisioner
  namespace: nfs-provisioner
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nfs-provisioner
  strategy:
    type: Recreate
  template:
    metadata:
      labels:
        app: nfs-provisioner
    spec:
      serviceAccount: nfs-provisioner
      containers:
        - name: nfs-provisioner
          image: registry.cn-hangzhou.aliyuncs.com/open-ali/nfs-client-provisioner
          volumeMounts:
            - name: nfs-client-root
              mountPath: /persistentvolumes
          env:
            - name: PROVISIONER_NAME
              value: example.com/nfs #provisioner name, make sure that this name is the same as the provisioner name in the nfs-storageclass. Yaml file
            - name: NFS_SERVER
              value: 172.202.10. #NFS Server IP address
            - name: NFS_PATH
              value: /nfsdata # NFS mount the volume
    volumes:
      - name: nfs-client-root
        nfs:
          server: 172.202.10. #NFS Server IP address
          path: /nfsdata # NFS mount the volume
Copy the code

[root@kubernetes-master nfs]# ll
total 20
-rw-r--r-- 1 root root  894 Dec  9 13:55 nfs-deployment.yaml
-rw-r--r-- 1 root root   65 Dec  9 14:50 nfs-namespace.yaml
-rw-r--r-- 1 root root 1449 Dec  9 15:15 nfs-rbac.yaml
-rw-r--r-- 1 root root  100 Dec  9 14:18 nfs-storageclass.yaml
Copy the code

Create the Pod and check the deployment

pvc-nfs.yaml

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc-nfs
spec:
accessModes:
   - ReadWriteOnce
storageClassName: nfs
resources:
  requests:
    storage: 1Gi
Copy the code

[root@kubernetes-master nfs]# kubectl apply -f pvc-nfs.yaml 
persistentvolumeclaim/pvc-nfs created
[root@kubernetes-master nfs]# kubectl get pvcNAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE pvc-nfs Bound pvc-7461b40b-f52e-4bf6-9d73-40432b77f108 1Gi RWO  nfs 1sCopy the code

Create a test pod to see if it can be mounted properly

kind: Pod
apiVersion: v1
metadata:
 name: test-pod
spec:
 containers:
 - name: test-pod
   image: Busybox: 1.24
   command:
     - "/bin/sh"
   args:
     - "-c"
     - "touch /mnt/SUCCESS && exit 0 || exit 1"   Create a SUCCESS file and exit
   volumeMounts:
     - name: pvc-nfs
       mountPath: "/mnt"
 restartPolicy: "Never"
 volumes:
   - name: pvc-nfs
     persistentVolumeClaim:
       claimName: pvc-nfs # Keep consistent with the PVC name
Copy the code

[root@nfs nfsdata]# ll default-pvc-nfs-pvc-7461b40b-f52e-4bf6-9d73-40432b77f108/
total 0
-rw-r--r-- 1 nfsnobody nfsnobody 0 Dec  9 15:29 SUCCESS # here is a file of SUCCESS, which proves that the above verification was successful
Copy the code