Pod数据持久化

• kubenetes中的Volume提供了在容器中挂载外部存储的能力

• Pod需要设置卷来源(spec.volume)和挂载点(spec.containers.volumeMounts)两个信息后才可以使用相应的Volume

常用卷

• 本地卷

  hostPath, emptyDir

• 网络卷

  nfs, ceph(cephfs,rbd), glusterfs

• 公有云

  aws, azure

• K8S资源

  downwardAPI, configMap, secret

emptyDir

创建一个空卷,挂载到Pod中的容器.Pod删除该卷也会被删除.

应用场景: Pod容器之间的数据共享

类似docker的volume类型

YAML配置

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
  - name: write
    image: centos
    command: ["bash","-c","for i in {1..100};do echo $i >> /data/hello;sleep 1;done"]
    volumeMounts:
      - name: data
        mountPath: /data

  - name: read
    image: centos
    command: ["bash","-c","tail -f /data/hello"]
    volumeMounts:
      - name: data
        mountPath: /data
  
  volumes:
  - name: data
    emptyDir: {}

容器数据卷位置:

/var/lib/kubelet/pods/POD_ID/volumes/kubernetes.io~empty-dir/data

hostPath

挂载Node文件系统上文件或者目录到Pod中的容器。

应用场景：Pod中容器需要访问宿主机文件

​ 日志采集agent, 监控agent,容器需要调用本机jdk,maven环境等

​ 一般配合DaemonSet控制器使用

类似docker的bindmount类型

YAML配置文件

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
  - name: busybox
    image: busybox
    args:
    - /bin/sh
    - -c
    - sleep 36000
    volumeMounts:
    - name: data
      mountPath: /data
  volumes:
  - name: data
    hostPath:
      path: /tmp
      type: Directory

NFS

安装NFS

yum install nfs-utils -y

配置NFS

cat > /etc/exports << EOF
/data/NFS/wwwroot *(rw,sync,no_root_squash)
EOF

启动NFS

systemctl start nfs

挂载验证

# 列出NFS共享目录
showmount -e 192.168.104.200
Export list for 192.168.104.200:
/data/NFS/wwwroot *
# 挂载共享目录
mount -t nfs 192.168.104.200:/data/NFS/wwwroot /mnt/wwwroot/

挂载节点也需要安装nfs-utils

YAML配置文件

nginx-pv.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: nginx
  name: nginx
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - image: nginx:latest
        name: nginx
        volumeMounts:
        - name: data
          mountPath: /usr/share/nginx/html

      volumes:
      - name: data
        nfs:
          server: 192.168.104.200
          path: /data/NFS/wwwroot

---

apiVersion: v1
kind: Service
metadata:
  name: nginx-service
  namespace: default
  labels:
    app: nginx
spec:
  selector:
    app: nginx
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
  type: NodePort

应用配置

kubectl apply -f nginx-pv.yaml

验证:

在NFS共享目录中创建一个index.html,访问pod的nginx,显示内容为NFS共享目录中的index.html即为生效

PersistentVolume (PV)

**PersistentVolume（PV）：**对存储资源创建和使用的抽象，使得存储作为集群中的资源管理

PV供给分为：

• 静态

• 动态

**PersistentVolumeClaim（PVC）：**让用户不需要关心具体的Volume实现细节

创建PV

deploy-pvc.yaml

apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-01
spec:
  capacity:
    storage: 10Gi
  accessModes:
    - ReadWriteMany
  nfs:
    path: /data/NFS/wwwroot/01
    server: 192.168.104.200

---

apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-02
spec:
  capacity:
    storage: 5Gi
  accessModes:
    - ReadWriteMany
  nfs:
    path: /data/NFS/wwwroot/02
    server: 192.168.104.200

应用 && 验证:

kubectl apply -f deploy-pvc.yaml
persistentvolume/pv-01 created
persistentvolume/pv-02 created

kubectl get pv
NAME    CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM   STORAGECLASS   REASON   AGE
pv-01   10Gi       RWX            Retain           Available                                   5s
pv-02   5Gi        RWX            Retain           Available                                   5s

创建PVC来消费PV

nginx-pvc.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: nginx
  name: nginx
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - image: nginx:latest
        name: nginx
        volumeMounts:
        - name: www
          mountPath: /usr/share/nginx/html

      volumes:
      - name: www
        persistentVolumeClaim:
          claimName: pvc-www
---
# 创建PVC
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc-www
spec:
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 2Gi

---

apiVersion: v1
kind: Service
metadata:
  name: nginx-service
  namespace: default
  labels:
    app: nginx
spec:
  selector:
    app: nginx
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
  type: NodePort

创建PVC时候不需要和PV关联,之后程序会自动根据大小匹配对应的PV

查看PV消费情况

kubectl get pv
NAME    CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM             STORAGECLASS   REASON   AGE
pv-01   10Gi       RWX            Retain           Available                                             14m
pv-02   5Gi        RWX            Retain           Bound       default/pvc-www                           14m

kubectl get pvc
NAME      STATUS   VOLUME   CAPACITY   ACCESS MODES   STORAGECLASS   AGE
pvc-www   Bound    pv-02    5Gi        RWX                           50s

验证

在NFS共享目录02中创建index.html,如果可以通过容器访问,即成功

一个PV对应一个PVC,PV容量不一定等于PVC

PV动态供给-NFS

Dynamic Provisioning机制工作的核心在于StorageClass的API对象。

StorageClass声明存储插件，用于自动创建PV。

Kubernetes支持动态供给的存储插件：

https://kubernetes.io/docs/concepts/storage/storage-classes

创建动态PV

nfs-client插件部署,插件地址:

https://github.com/kubernetes-retired/external-storage/tree/master/nfs-client/deploy

下载deploy下的class.yaml deployment.yaml rbac.yaml

1. 修改deployment.yaml的image地址为lizhenliang/nfs-client-provisioner:latest
2. 修改NFS地址和共享路径

查看

kubectl get sc
NAME                  PROVISIONER      RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE
managed-nfs-storage   fuseim.pri/ifs   Delete          Immediate           false                  16m

消费动态PV

nginx-dynamic-pvc.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: nginx
  name: nginx
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - image: nginx:latest
        name: nginx
        volumeMounts:
        - name: www
          mountPath: /usr/share/nginx/html

      volumes:
      - name: www
        persistentVolumeClaim:
          claimName: pvc-www02
---

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc-www02
spec:
  storageClassName: managed-nfs-storage
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 3Gi

---

apiVersion: v1
kind: Service
metadata:
  name: nginx-service
  namespace: default
  labels:
    app: nginx
spec:
  selector:
    app: nginx
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
  type: NodePort

查看结果

kubectl get pv
kubectl get pvc
kubectl get sc