存储卷

Damoncai 10/13/2022 k8s,运维

# kubernetes持久化存储卷

# 一、存储卷介绍

pod有生命周期，生命周期结束后pod里的数据会消失(如配置文件,业务数据等)。

解决: 我们需要将数据与pod分离,将数据放在专门的存储卷上

pod在k8s集群的节点中是可以调度的, 如果pod挂了被调度到另一个节点,那么数据和pod的联系会中断。

解决: 所以我们需要与集群节点分离的存储系统才能实现数据持久化

简单来说: volume提供了在容器上挂载外部存储的能力

# 二、存储卷的分类

kubernetes支持的存储卷类型非常丰富,使用下面的命令查看:

# kubectl explain pod.spec.volumes

或者参考: https://kubernetes.io/docs/concepts/storage/

kubernetes支持的存储卷列表如下:

我们将上面的存储卷列表进行简单的分类:

本地存储卷
- emptyDir pod删除,数据也会被清除, 用于数据的临时存储
- hostPath 宿主机目录映射(本地存储卷)
网络存储卷
- NAS类 nfs等
- SAN类 iscsi,FC等
- 分布式存储 glusterfs,cephfs,rbd,cinder等
- 云存储 aws,azurefile等

# 三、存储卷的选择

市面上的存储产品种类繁多, 但按应用角度主要分为三类:

文件存储如:nfs,glusterfs,cephfs等
- 优点: 数据共享(多pod挂载可以同读同写)
- 缺点: 性能较差
块存储如: iscsi,rbd等
- 优点: 性能相对于文件存储好
- 缺点: 不能实现数据共享（部分）
对象存储如: ceph对象存储
- 优点: 性能好, 数据共享
- 缺点: 使用方式特殊,支持较少

面对kubernetes支持的形形色色的存储卷,如何选择成了难题。在选择存储时,我们要抓住核心需求:

数据是否需要持久性
数据可靠性如存储集群节点是否有单点故障,数据是否有副本等
性能
扩展性如是否能方便扩容,应对数据增长的需求
运维难度存储的运维难度是比较高的,尽量选择稳定的开源方案或商业产品
成本

总之, 存储的选择是需要考虑很多因素的, 熟悉各类存储产品, 了解它们的优缺点，结合自身需求才能选择合适自己的。

# 四、本地存储卷之emptyDir

应用场景

实现pod内容器之间数据共享
特点

随着pod被删除，该卷也会被删除

创建yaml文件

vim volume-emptydir.yml

apiVersion: v1
kind: Pod
metadata:
  name: volume-emptydir
spec:
  containers:
  - name: write
    image: centos
    imagePullPolicy: IfNotPresent
    command: ["bash","-c","echo haha > /data/1.txt ; sleep 6000"]
    volumeMounts:
    - name: data
      mountPath: /data

  - name: read
    image: centos
    imagePullPolicy: IfNotPresent
    command: ["bash","-c","cat /data/1.txt; sleep 6000"]
    volumeMounts:
    - name: data
      mountPath: /data
      
  volumes:
  - name: data
    emptyDir: {}

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基于yaml文件创建pod

kubectl apply -f volume-emptydir.yml
pod/volume-emptydir created

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查看pod启动情况

kubectl get pods |grep volume-emptydir
NAME                               READY   STATUS    RESTARTS   AGE
volume-emptydir                    2/2     Running   0          15s

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查看pod描述信息

kubectl describe pod volume-emptydir | tail -10
Events:
  Type    Reason     Age   From               Message
  ----    ------     ----  ----               -------
  Normal  Scheduled  50s   default-scheduler  Successfully assigned default/volume-emptydir to k8s-worker1
  Normal  Pulling    50s   kubelet            Pulling image "centos:centos7"
  Normal  Pulled     28s   kubelet            Successfully pulled image "centos:centos7" in 21.544912361s
  Normal  Created    28s   kubelet            Created container write
  Normal  Started    28s   kubelet            Started container write
  Normal  Pulled     28s   kubelet            Container image "centos:centos7" already present on machine
  Normal  Created    28s   kubelet            Created container read
  Normal  Started    28s   kubelet            Started container read

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验证

kubectl logs volume-emptydir -c write

kubectl logs volume-emptydir -c read
haha

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# 五、本地存储卷之hostPath

应用场景

pod内与集群节点目录映射（pod中容器想访问节点上数据，例如监控，只有监控访问到节点主机文件才能知道集群节点主机状态）
缺点

如果集群节点挂掉，控制器在另一个集群节点拉起容器，数据就会变成另一台集群节点主机的了（无法实现数据共享)

创建yaml文件

vim volume-hostpath.yml

apiVersion: v1
kind: Pod
metadata:
  name: volume-hostpath
spec:
  containers:
  - name: busybox
    image: busybox
    imagePullPolicy: IfNotPresent
    command: ["/bin/sh","-c","echo haha > /data/1.txt ; sleep 600"]
    volumeMounts:
    - name: data
      mountPath: /data
      
  volumes:
  - name: data
    hostPath:
      path: /opt
      type: Directory

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基于yaml文件创建pod

kubectl apply  -f volume-hostpath.yml
pod/volume-hostpath created

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查看pod状态

kubectl get pods -o wide |grep volume-hostpath
volume-hostpath     1/1   Running   0    29s     10.224.194.120   k8s-worker1   <none>     <none>
可以看到pod是在k8s-worker1节点上

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验证pod所在机器上的挂载文件

cat /opt/1.txt
haha

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# 六、网络存储卷之nfs

搭建nfs服务器

找一台主机做为nfs服务器

yum -y install nfs-utils rpcbind

mkdir -p /data/nfs

vim /etc/exports

/data/nfs       *(rw,no_root_squash,sync)

systemctl restart nfs-server

systemctl enable nfs-server

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所有node节点安装nfs客户端相关软件包

yum install nfs-utils -y

验证nfs可用性

ha02主机上
showmount -e 192.168.100.101

Export list for 192.168.10.129:
/data/nfs *

ha03主机上
showmount -e 192.168.100.101

Export list for 192.168.10.129:
/data/nfs *

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master节点上创建yaml文件

vim volume-nfs.yml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: volume-nfs
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.15-alpine
        imagePullPolicy: IfNotPresent
        volumeMounts:
        - name: documentroot
          mountPath: /usr/share/nginx/html
        ports:
        - containerPort: 80
      volumes:
      - name: documentroot
        nfs:
          server: 192.168.100.101
          path: /data/nfs

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应用yaml创建

kubectl apply -f volume-nfs.yml

在nfs服务器共享目录中创建验证文件

echo "volume-nfs" > /data/nfs/index.html

验证pod

kubectl get pod |grep volume-nfs
volume-nfs-649d848b57-qg4bz   1/1     Running   0          10s
volume-nfs-649d848b57-wrnpn   1/1     Running   0          10s

kubectl exec -it volume-nfs-649d848b57-qg4bz -- /bin/sh
/ # ls /usr/share/nginx/html/
index.html
/ # cat /usr/share/nginx/html/index.html
volume-nfs										# 文件内容与nfs服务器上创建的一致
/ # exit

kubectl exec -it volume-nfs-649d848b57-wrnpn -- /bin/sh
/ # ls /usr/share/nginx/html/
index.html
/ # cat /usr/share/nginx/html/index.html
volume-nfs										# 文件内容与nfs服务器上创建的一致
/ # exit

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# 七、PV(持久存储卷)与PVC(持久存储卷声明)

# 7.1 认识pv与pvc

kubernetes存储卷的分类太丰富了,每种类型都要写相应的接口与参数才行，这就让维护与管理难度加大。

persistenvolume(PV) 是配置好的一段存储(可以是任意类型的存储卷)

也就是说将网络存储共享出来,配置定义成PV。

PersistentVolumeClaim(PVC)是用户pod使用PV的申请请求。

用户不需要关心具体的volume实现细节,只需要关心使用需求。

# 7.2 pv与pvc之间的关系

pv提供存储资源(生产者)
pvc使用存储资源(消费者)
使用pvc绑定pv

# 7.3 实现nfs类型pv与pvc

编写创建pv的YAML文件

vim pv-nfs.yml

apiVersion: v1
kind: PersistentVolume						# 类型为PersistentVolume(pv)
metadata:		
  name: pv-nfs								# 名称
spec:
  capacity:
    storage: 1Gi							# 大小
  accessModes:
    - ReadWriteMany							# 访问模式
  nfs:
    path: /data/nfs							# nfs共享目录
    server: 192.168.100.101					# nfs服务器IP

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访问模式有3种参考: https://kubernetes.io/docs/concepts/storage/persistent-volumes/#access-modes

ReadWriteOnce 单节点读写挂载
ReadOnlyMany 多节点只读挂载
ReadWriteMany 多节点读写挂载

cephfs存储卷3种类型都支持, 我们要实现多个nginx跨节点之间的数据共享,所以选择ReadWriteMany模式。

创建pv并验证

kubectl apply -f pv-nfs.yml
persistentvolume/pv-nfs created

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kubectl get pv
NAME     CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM   STORAGECLASS   REASON   AGE
pv-nfs   1Gi        RWX            Retain           Available                                   81s

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说明:

RWX为ReadWriteMany的简写
Retain是回收策略
- Retain表示需要不使用了需要手动回收
- 参考: https://kubernetes.io/docs/concepts/storage/persistent-volumes/#reclaim-policy

编写创建pvc的YAML文件

vim pvc-nfs.yml

apiVersion: v1
kind: PersistentVolumeClaim				# 类型为PersistentVolumeClaim(pvc)
metadata:
  name: pvc-nfs							# pvc的名称
spec:
  accessModes:
    - ReadWriteMany						# 访问模式
  resources:
    requests:
      storage: 1Gi						# 大小要与pv的大小保持一致

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创建pvc并验证

kubectl apply -f pvc-nfs.yml
persistentvolumeclaim/pvc-nfs created

kubectl get pvc
NAME      STATUS   VOLUME   CAPACITY   ACCESS MODES   STORAGECLASS   AGE
pvc-nfs   Bound    pv-nfs   1Gi        RWX                           38s

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注意: STATUS必须为Bound状态(Bound状态表示pvc与pv绑定OK)

编写deployment的YMAL

vim deploy-nginx-nfs.yml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: deploy-nginx-nfs
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.15-alpine
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 80
        volumeMounts:
        - name: www
          mountPath: /usr/share/nginx/html
      volumes:
      - name: www
        persistentVolumeClaim:
          claimName: pvc-nfs

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应用YAML创建deploment

kubectl apply -f deploy-nginx-nfs.yml
deployment.apps/deploy-nginx-nfs created

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验证pod

kubectl get pod |grep deploy-nginx-nfs
deploy-nginx-nfs-6f9bc4546c-gbzcl   1/1     Running   0          1m46s
deploy-nginx-nfs-6f9bc4546c-hp4cv   1/1     Running   0          1m46s

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验证pod内卷的数据

[kubectl exec -it deploy-nginx-nfs-6f9bc4546c-gbzcl -- /bin/sh
/ # ls /usr/share/nginx/html/
index.html
/ # cat /usr/share/nginx/html/index.html
volume-nfs
/ # exit


kubectl exec -it deploy-nginx-nfs-6f9bc4546c-hp4cv -- /bin/sh
/ # ls /usr/share/nginx/html/
index.html
/ # cat /usr/share/nginx/html/index.html
volume-nfs
/ # exit

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# 八、存储的动态供给

# 8.1 什么是动态供给

每次使用存储要先创建pv, 再创建pvc，真累! 所以我们可以实现使用存储的动态供给特性。

静态存储需要用户申请PVC时保证容量和读写类型与预置PV的容量及读写类型完全匹配, 而动态存储则无需如此.
管理员无需预先创建大量的PV作为存储资源

Kubernetes从1.4版起引入了一个新的资源对象StorageClass，可用于将存储资源定义为具有显著特性的类（Class）而不是具体

的PV。用户通过PVC直接向意向的类别发出申请，匹配由管理员事先创建的PV，或者由其按需为用户动态创建PV，这样就免去

了需要先创建PV的过程。

# 8.2 使用NFS文件系统创建存储动态供给

PV对存储系统的支持可通过其插件来实现，目前，Kubernetes支持如下类型的插件。

官方地址：https://kubernetes.io/docs/concepts/storage/storage-classes/

官方插件是不支持NFS动态供给的，但是我们可以用第三方的插件来实现

第三方插件地址: https://github.com/kubernetes-retired/external-storage

1.下载并创建storageclass

[root@k8s-master1 ~]# wget https://raw.githubusercontent.com/kubernetes-sigs/nfs-subdir-external-provisioner/master/deploy/class.yaml

[root@k8s-master1 ~]# mv class.yaml storageclass-nfs.yml

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[root@k8s-master1 ~]# cat storageclass-nfs.yml
apiVersion: storage.k8s.io/v1
kind: StorageClass				# 类型
metadata:
  name: nfs-client		# 名称,要使用就需要调用此名称
provisioner: k8s-sigs.io/nfs-subdir-external-provisioner 	# 动态供给插件
parameters:
  archiveOnDelete: "false"		# 删除数据时是否存档，false表示不存档，true表示存档

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[root@k8s-master1 ~]# kubectl apply -f storageclass-nfs.yml
storageclass.storage.k8s.io/managed-nfs-storage created

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[root@k8s-master1 ~]# kubectl get storageclass
NAME         PROVISIONER                                   RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE
nfs-client   k8s-sigs.io/nfs-subdir-external-provisioner   Delete          Immediate           false                  10s

# RECLAIMPOLICY pv回收策略，pod或pvc被删除后，pv是否删除还是保留。
# VOLUMEBINDINGMODE Immediate 模式下PVC与PV立即绑定，主要是不等待相关Pod调度完成，不关心其运行节点，直接完成绑定。相反的 WaitForFirstConsumer模式下需要等待Pod调度完成后进行PV绑定。
# ALLOWVOLUMEEXPANSION pvc扩容

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2.下载并创建rbac

因为storage自动创建pv需要经过kube-apiserver，所以需要授权。

[root@k8s-master1 ~]# wget https://raw.githubusercontent.com/kubernetes-sigs/nfs-subdir-external-provisioner/master/deploy/rbac.yaml

[root@k8s-master1 ~]# mv rbac.yaml storageclass-nfs-rbac.yaml

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[root@k8s-master1 ~]# cat storageclass-nfs-rbac.yaml
apiVersion: v1
kind: ServiceAccount
metadata:
  name: nfs-client-provisioner
  # replace with namespace where provisioner is deployed
  namespace: default
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: nfs-client-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-client-provisioner
subjects:
  - kind: ServiceAccount
    name: nfs-client-provisioner
    # replace with namespace where provisioner is deployed
    namespace: default
roleRef:
  kind: ClusterRole
  name: nfs-client-provisioner-runner
  apiGroup: rbac.authorization.k8s.io
---
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: leader-locking-nfs-client-provisioner
  # replace with namespace where provisioner is deployed
  namespace: default
rules:
  - apiGroups: [""]
    resources: ["endpoints"]
    verbs: ["get", "list", "watch", "create", "update", "patch"]
---
kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: leader-locking-nfs-client-provisioner
  # replace with namespace where provisioner is deployed
  namespace: default
subjects:
  - kind: ServiceAccount
    name: nfs-client-provisioner
    # replace with namespace where provisioner is deployed
    namespace: default
roleRef:
  kind: Role
  name: leader-locking-nfs-client-provisioner
  apiGroup: rbac.authorization.k8s.io

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[root@k8s-master1 ~]# kubectl apply -f rbac.yaml
serviceaccount/nfs-client-provisioner created
clusterrole.rbac.authorization.k8s.io/nfs-client-provisioner-runner created
clusterrolebinding.rbac.authorization.k8s.io/run-nfs-client-provisioner created
role.rbac.authorization.k8s.io/leader-locking-nfs-client-provisioner created
rolebinding.rbac.authorization.k8s.io/leader-locking-nfs-client-provisioner created

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3.创建动态供给的deployment

需要一个deployment来专门实现pv与pvc的自动创建

[root@k8s-master1 ~]# vim deploy-nfs-client-provisioner.yml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nfs-client-provisioner
spec:
  replicas: 1
  strategy:
    type: Recreate
  selector:
    matchLabels:
      app: nfs-client-provisioner
  template:
    metadata:
      labels:
        app: nfs-client-provisioner
    spec:
      serviceAccount: nfs-client-provisioner
      containers:
        - name: nfs-client-provisioner
          image: registry.cn-beijing.aliyuncs.com/pylixm/nfs-subdir-external-provisioner:v4.0.0
          volumeMounts:
            - name: nfs-client-root
              mountPath: /persistentvolumes
          env:
            - name: PROVISIONER_NAME
              value: k8s-sigs.io/nfs-subdir-external-provisioner
            - name: NFS_SERVER
              value: 192.168.10.129
            - name: NFS_PATH
              value: /data/nfs
      volumes:
        - name: nfs-client-root
          nfs:
            server: 192.168.10.129
            path: /data/nfs

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[root@k8s-master1 ~]# kubectl apply -f deploy-nfs-client-provisioner.yml
deployment.apps/nfs-client-provisioner created

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[root@k8s-master1 ~]# kubectl get pods |grep nfs-client-provisioner
nfs-client-provisioner-5b5ddcd6c8-b6zbq   1/1     Running   0          34s

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测试存储动态供给是否可用

# vim nginx-sc.yaml

---
apiVersion: v1
kind: Service
metadata:
  name: nginx
  labels:
    app: nginx
spec:
  ports:
  - port: 80
    name: web
  clusterIP: None
  selector:
    app: nginx
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: web
spec:
  selector:
    matchLabels:
      app: nginx
  serviceName: "nginx"
  replicas: 2
  template:
    metadata:
      labels:
        app: nginx
    spec:
      imagePullSecrets:
      - name: huoban-harbor
      terminationGracePeriodSeconds: 10
      containers:
      - name: nginx
        image: nginx:latest
        ports:
        - containerPort: 80
          name: web
        volumeMounts:
        - name: www
          mountPath: /usr/share/nginx/html
  volumeClaimTemplates:
  - metadata:
      name: www
    spec:
      accessModes: [ "ReadWriteOnce" ]
      storageClassName: "nfs-client"
      resources:
        requests:
          storage: 1Gi

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[root@k8s-master1 nfs]# kubectl get pods
NAME                                     READY   STATUS    RESTARTS   AGE
nfs-client-provisioner-9c988bc46-pr55n   1/1     Running   0          95s
web-0                                    1/1     Running   0          95s
web-1                                    1/1     Running   0          61s

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[root@nfsserver ~]# ls /data/nfs/
default-www-web-0-pvc-c4f7aeb0-6ee9-447f-a893-821774b8d11f  default-www-web-1-pvc-8b8a4d3d-f75f-43af-8387-b7073d07ec01

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扩展：

批量下载文件：
# for file in class.yaml deployment.yaml rbac.yaml  ; do wget https://raw.githubusercontent.com/kubernetes-incubator/external-storage/master/nfs-client/deploy/$file ; done

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Nginx-Ingress

西门小狼狗

Choose mode

存储卷

存储卷

# kubernetes持久化存储卷

# 一、存储卷介绍

# 二、存储卷的分类

# 三、存储卷的选择

# 四、本地存储卷之emptyDir

# 五、本地存储卷之hostPath

# 六、网络存储卷之nfs

# 七、PV(持久存储卷)与PVC(持久存储卷声明)

# 7.1 认识pv与pvc

# 7.2 pv与pvc之间的关系

# 7.3 实现nfs类型pv与pvc

# 八、存储的动态供给

# 8.1 什么是动态供给

# 8.2 使用NFS文件系统创建存储动态供给