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关于 Kubernetes中Volume的一些笔记

小半 • • 云原生 • 阅读 81

写在前面

  • 学习K8s，刚把这一块学完，整理笔记，理论很少，偏实战，适合温习

  • 博文内容涉及：

    • 常见nfs,hostPath,emptyDir数据卷类型

    • PV+PVC的创建

    • 持久性存储及动态卷供应

男女情事,谁先动心谁吃亏,越吃亏越难忘,到最后,到底是喜欢对方呢,还是喜欢自己,都搞不清楚了,答案偏偏在对方身上,所以才说,由爱故生忧。——–《剑来》

数据卷(Volume)管理

Volume是Pod中能够被多个容器访问的共享目录。Kuberetes的Volume概念、用途和目的与Docker的Volume比较类似,但两者不能等价。

Volume (存储卷)
Kubernetes中的Volume定义在Pod上,然后被一个Pod里的多个容器挂载到具体的文件目录下;
Kubernetes中的Volume与Pod的生命周期相同,但与容器的生命周期不相关,当容器终止或者重启时, Volume中的数据也不会丢失。
Kubernetes支持多种类型的Volume,例如GlusterFS, Ceph等先进的分布式文件系统。

Volume的使用也比较简单,在大多数情况下,我们先在Pod上声明一个Volume,然后在容器里引用该Volume并Mount到容器里的某个目录上。举例来说,我们要给之前的Tomcat Pod增加一个名字为datavol的Volume,并且Mount到容器的/mydata-data目录上,则只要对Pod的定义文件做如下修正即可(注意黑体字部分):

template:
  metadata:
    labels:
      app: app-demo
      tier: frontend
  spec:
    volumes:
      - name: datavol
        emptyDir: {}
    containers:
    - name: tomcat-demo
      image: tomcat
      volumeMounts:
        - mountPath: /myddata-data
          name: datavol
      imagePullPolicy: IfNotPresent

除了可以让一个Pod里的多个容器共享文件、让容器的数据写到宿主机的磁盘上或者写文件到网络存储中, Kubernetes的Volume还扩展出了一种非常有实用价值的功能,即 ：容器配置文件集中化定义与管理,这是通过ConfigMap这个新的资源对象来实现的.

Kubernetes提供了非常丰富的Volume类型

学习环境准备

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$mkdir k8s-volume-create;cd k8s-volume-create
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl get ns
NAME                   STATUS   AGE
default                Active   49d
kube-node-lease        Active   49d
kube-public            Active   49d
kube-system            Active   49d
liruilong              Active   49d
liruilong-pod-create   Active   41d
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl  create ns liruilong-volume-create
namespace/liruilong-volume-create created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl config set-context $(kubectl config current-context) --namespace=liruilong-volume-create
Context "context1" modified.
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl config get-contexts
CURRENT   NAME       CLUSTER    AUTHINFO            NAMESPACE
          cluster1                                  default
*         context1   cluster1   kubernetes-admin1   liruilong-volume-create
          context2                                  kube-system

emptyDir

一个emptyDir Volume是在Pod分配到Node时创建的。从它的名称就可以看出,它的初始内容为空,并且无须指定宿主机上对应的目录文件,因为这是 Kubernetes自动分配的一个目录,而且这个目录实际是挂载中物理机内存中的的，当Pod从Node上移除时, emptyDir中的数据也会被永久删除。

emptyDir的一些用途如下:

emptyDir的一些用途
临时空间,例如用于某些应用程序运行时所需的临时目录,且无须永久保留。
长时间任务的中间过程CheckPoint的临时保存目录。
一个容器需要从另一个容器中获取数据的目录(多容器共享目录)

创建一个Pod，声明volume卷

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: podvolume
  name: podvolume
spec:
  volumes:
  - name: volume1
    emptyDir: {}
  - name: volume2
    emptyDir: {}
  containers:
  - image: busybox
    imagePullPolicy: IfNotPresent
    command: ['sh','-c','sleep 5000']
    resources: {}
    name: podvolume1
    volumeMounts:
    - mountPath: /liruilong
      name: volume1
  - image: busybox
    imagePullPolicy: IfNotPresent
    name: podvolume2
    volumeMounts:
    - mountPath: /liruilong
      name: volume2
    command: ['sh','-c','sleep 5000']
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}

创建pod，查看运行状态

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl apply  -f pod_volume.yaml
pod/podvolume configured
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl get pods -o wide
NAME        READY   STATUS             RESTARTS         AGE   IP             NODE                         NOMINATED NODE   READINESS GATES
podvolume   0/2     CrashLoopBackOff   164 (117s ago)   37h   10.244.70.14   vms83.liruilongs.github.io   <none>           <none>
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$

查看pod的数据卷类型

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl describe  pod podvolume | grep -A2 Volumes
Volumes:
  volume1:
    Type:       EmptyDir (a temporary directory that shares a pod's lifetime)

通过docker命令来查看对应的宿主机容器

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$ansible 192.168.26.83 -m shell -a "docker ps | grep podvolume"
192.168.26.83 | CHANGED | rc=0 >>
bbb287afc518   cabb9f684f8b                                          "sh -c 'sleep 5000'"     12 minutes ago   Up 12 minutes             k8s_podvolume2_podvolume_liruilong-volume-create_76b518f6-9575-4412-b161-f590ab3c3135_0
dcbf5c63263f   cabb9f684f8b                                          "sh -c 'sleep 5000'"     12 minutes ago   Up 12 minutes             k8s_podvolume1_podvolume_liruilong-volume-create_76b518f6-9575-4412-b161-f590ab3c3135_0
5bb9ee2ed134   registry.aliyuncs.com/google_containers/pause:3.4.1   "/pause"                 12 minutes ago   Up 12 minutes             k8s_POD_podvolume_liruilong-volume-create_76b518f6-9575-4412-b161-f590ab3c3135_0
┌──[root@vms81.liruilongs.github.io]-[~/ansible]

通过inspect查看映射的宿主机信息

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$ansible 192.168.26.83 -m shell -a "docker inspect dcbf5c63263f | grep -A5 Mounts"
192.168.26.83 | CHANGED | rc=0 >>
        "Mounts": [
            {
                "Type": "bind",
                "Source": "/var/lib/kubelet/pods/76b518f6-9575-4412-b161-f590ab3c3135/volumes/kubernetes.io~empty-dir/volume1",
                "Destination": "/liruilong",
                "Mode": "",
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$ansible 192.168.26.83 -m shell -a "docker inspect bbb287afc518 | grep -A5 Mounts"
192.168.26.83 | CHANGED | rc=0 >>
        "Mounts": [
            {
                "Type": "bind",
                "Source": "/var/lib/kubelet/pods/76b518f6-9575-4412-b161-f590ab3c3135/volumes/kubernetes.io~empty-dir/volume2",
                "Destination": "/liruilong",
                "Mode": "",
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$

pod内多容器数据卷共享

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$sed 's/podvolume/podvolumes/' pod_volume.yaml >pod_volumes.yaml
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$vim pod_volumes.yaml

编写pod_volumes.yaml文件

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: podvolumes
  name: podvolumes
spec:
  volumes:
  - name: volume1
    emptyDir: {}
  containers:
  - image: busybox
    imagePullPolicy: IfNotPresent
    command: ['sh','-c','sleep 5000']
    resources: {}
    name: podvolumes1
    volumeMounts:
    - mountPath: /liruilong
      name: volume1
  - image: busybox
    imagePullPolicy: IfNotPresent
    name: podvolumes2
    volumeMounts:
    - mountPath: /liruilong
      name: volume1
    command: ['sh','-c','sleep 5000']
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}

新建的文件夹中两个pod中同时存在

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl apply  -f pod_volumes.yaml
pod/podvolumes created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl exec -it podvolumes -c podvolumes1 -- sh
/ # mkdir -p /liruilong/$(date +"%Y%m%d%H%M%S");cd /liruilong/;ls
20211127080726
/liruilong #
/liruilong # exit
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl exec -it podvolumes -c podvolumes2 -- sh
/ # cd /liruilong/;ls
20211127080726
/liruilong #

设置数据卷的读写权限

pod_volume_r.yaml:设置数据卷pod1只读

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: podvolume
  name: podvolume
spec:
  volumes:
  - name: volume1
    emptyDir: {}
  - name: volume2
    emptyDir: {}
  containers:
  - image: busybox
    imagePullPolicy: IfNotPresent
    command: ['sh','-c','sleep 5000']
    resources: {}
    name: podvolume1
    volumeMounts:
    - mountPath: /liruilong
      name: volume1
      readOnly: true # 设置数据卷pod1只读
  - image: busybox
    imagePullPolicy: IfNotPresent
    name: podvolume2
    volumeMounts:
    - mountPath: /liruilong
      name: volume2
    command: ['sh','-c','sleep 5000']
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl exec  -it podvolume -c podvolume1 -- sh
/ # cd liruilong/;touch lrl.txt
touch: lrl.txt: Read-only file system
/liruilong #
/liruilong # exit
command terminated with exit code 1
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl exec  -it podvolume -c podvolume2 -- sh
/ # cd liruilong/;touch lrl.txt
/liruilong # ls
lrl.txt
/liruilong #

hostPath

hostPath为在Pod上挂载宿主机上的文件或目录,它通常可以用于以下几方面。

hostPath的应用
容器应用程序生成的日志文件需要永久保存时,可以使用宿主机的高速文件系统进行存储。
需要访问宿主机上Docker引擎内部数据结构的容器应用时,可以通过定义hostPath为宿主机/var/lib/docker目录,使容器内部应用可以直接访问Docker的文件系统。

在使用这种类型的Volume时,需要注意以下几点。

在不同的Node上具有相同配置的Pod可能会因为宿主机上的目录和文件不同而导致对Volume上目录和文件的访问结果不一致。

如果使用了资源配额管理,则Kubernetes无法将hostPath在宿主机上使用的资源纳入管理cgroup。在下面的例子中使用宿主机的/data目录定义了一个hostPath类型的Volume:

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: podvolumehostpath
  name: podvolumehostpath
spec:
  volumes:
  - name: volumes1
    hostPath:
      path: /data
  containers:
  - image: busybox
    name: podvolumehostpath
    command: ['sh','-c','sleep 5000']
    resources: {}
    volumeMounts:
    - mountPath: /liruilong
      name: volumes1
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl apply  -f PodVolumeHostPath.yaml
pod/podvolumehostpath created

宿主机创建一个文件

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl  get pod -o wide
NAME                READY   STATUS    RESTARTS   AGE     IP            NODE                         NOMINATED NODE   READINESS GATES
podvolumehostpath   1/1     Running   0          5m44s   10.244.70.9   vms83.liruilongs.github.io   <none>           <none>
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$cd ..
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$ansible 192.168.26.83 -m shell -a "cd /data;touch liruilong"
192.168.26.83 | CHANGED | rc=0 >>

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$ansible 192.168.26.83 -m shell -a "cd /data;ls"
192.168.26.83 | CHANGED | rc=0 >>
liruilong
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$

pod容器内同样存在

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$kubectl exec -it podvolumehostpath -- sh
/ # ls
bin        dev        etc        home       liruilong  proc       root       sys        tmp        usr        var
/ # cd liruilong/;ls
liruilong
/liruilong #

NFS

不管是emptyDir还是hostPath，数据都是存放到宿主机，但是如某个pod出现了问题，通过控制器重启时，会通过调度生产一个新的Pod，如果调度的节点不是原来的节点，那么数据就会丢失。这里的话，使用网路存储就很方便。

部署一个NFSServer

使用NFS网络文件系统提供的共享目录存储数据时,我们需要在系统中部署一个NFSServer

┌──[root@vms81.liruilongs.github.io]-[~]
└─$yum -y install nfs-utils.x86_64
┌──[root@vms81.liruilongs.github.io]-[~]
└─$systemctl enable nfs-server.service  --now
┌──[root@vms81.liruilongs.github.io]-[~]
└─$mkdir -p /liruilong
┌──[root@vms81.liruilongs.github.io]-[/liruilong]
└─$cd /liruilong/;echo `date` > liruilong.txt
┌──[root@vms81.liruilongs.github.io]-[/liruilong]
└─$cd /liruilong/;cat  liruilong.txt
2021年 11月 27日 星期六 21:57:10 CST
┌──[root@vms81.liruilongs.github.io]-[/liruilong]
└─$cat /etc/exports
┌──[root@vms81.liruilongs.github.io]-[/liruilong]
└─$echo "/liruilong *(rw,sync,no_root_squash)" > /etc/exports
┌──[root@vms81.liruilongs.github.io]-[/liruilong]
└─$exportfs -arv
exporting *:/liruilong
┌──[root@vms81.liruilongs.github.io]-[/liruilong]
└─$showmount -e
Export list for vms81.liruilongs.github.io:
/liruilong *
┌──[root@vms81.liruilongs.github.io]-[/liruilong]
└─$

然后我们需要在所有的工作节点安装nfs-utils，然后挂载

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$ansible node -m shell -a "yum -y install nfs-utils"
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$ansible node -m shell -a "systemctl enable nfs-server.service  --now"

nfs共享文件测试

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$ansible node -m shell -a "showmount -e vms81.liruilongs.github.io"
192.168.26.83 | CHANGED | rc=0 >>
Export list for vms81.liruilongs.github.io:
/liruilong *
192.168.26.82 | CHANGED | rc=0 >>
Export list for vms81.liruilongs.github.io:
/liruilong *
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$

挂载测试

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$ansible node  -m shell -a "mount  vms81.liruilongs.github.io:/liruilong /mnt"

192.168.26.82 | CHANGED | rc=0 >>

192.168.26.83 | CHANGED | rc=0 >>

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$ansible node -m shell -a "cd /mnt/;ls"
192.168.26.83 | CHANGED | rc=0 >>
liruilong.txt
192.168.26.82 | CHANGED | rc=0 >>
liruilong.txt
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$ansible node -m shell -a "df -h | grep  liruilong"
192.168.26.82 | CHANGED | rc=0 >>
vms81.liruilongs.github.io:/liruilong  150G  8.3G  142G    6% /mnt
192.168.26.83 | CHANGED | rc=0 >>
vms81.liruilongs.github.io:/liruilong  150G  8.3G  142G    6% /mnt

取消挂载

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$ansible node  -m shell -a "umount /mnt"

使用nfs数据卷pod资源yaml文件

podvolumenfs.yaml

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: podvolumehostpath
  name: podvolumehostpath
spec:
  volumes:
  - name: volumes1
    nfs:
      server: vms81.liruilongs.github.io
      path: /liruilong
  containers:
  - image: busybox
    name: podvolumehostpath
    command: ['sh','-c','sleep 5000']
    resources: {}
    volumeMounts:
    - mountPath: /liruilong
      name: volumes1
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}

创建nfs数据卷 pod

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl apply -f podvolumenfs.yaml
pod/podvolumehostpath created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl get pods -o wide
NAME                READY   STATUS    RESTARTS   AGE   IP               NODE                         NOMINATED NODE   READINESS GATES
podvolumehostpath   1/1     Running   0          24s   10.244.171.182   vms82.liruilongs.github.io   <none>           <none>
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl exec -it podvolumehostpath -- sh
/ # cd liruilong/;ls
liruilong.txt
/liruilong # exit
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$

持久性存储(Persistent Volume)

Volume是定义在Pod上的,属于“计算资源”的一部分,而实际上, “网络存储”是相对独立于“计算资源”而存在的一种实体资源。比如在使用虚拟机的情况下,我们通常会先定义一个网络存储,然后从中划出一个“网盘”并挂接到虚拟机上

Persistent Volume(简称PV)和与之相关联的Persistent Volume Claim (简称PVC)也起到了类似的作用。PV可以理解成 Kubernetes集群中的某个网络存储中对应的一块存储,它与Volume很类似,但有以下区别。

这里也可以结合物理盘区和逻辑卷来理解，PV可以理解为物理卷，PVC可以理解为划分的逻辑卷。

Persistent Volume与Volume的区别
PV只能是网络存储,不属于任何Node,但可以在每个Node上访问。
PV并不是定义在Pod上的,而是独立于Pod之外定义。
PV目前支持的类型包括: gcePersistentDisk、 AWSElasticBlockStore, AzureFileAzuRedisk, FC (Fibre Channel). Flocker, NFS, isCSI, RBD (Rados Block Device)CephFS. Cinder, GlusterFS. VsphereVolume. Quobyte Volumes, VMware Photon.PortworxVolumes, ScalelO Volumes和HostPath (仅供单机测试)。

pv的创建

PV的accessModes属性, 目前有以下类型:

  • ReadWriteOnce:读写权限、并且只能被单个Node挂载。

  • ReadOnlyMany:只读权限、允许被多个Node挂载。

  • ReadWriteMany:读写权限、允许被多个Node挂载。

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl get pv
No resources found
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$vim pod_volunms-pv.yaml
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv0003
spec:
  capacity:
    storage: 5Gi
  volumeMode: Filesystem
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Recycle
  #storageClassName: slow
  mountOptions:
    - hard
    - nfsvers=4.1
  nfs:
    path: /tmp
    server: vms81.liruilongs.github.io
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$cat  /etc/exports
/liruilong *(rw,sync,no_root_squash)
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$echo "/tmp *(rw,sync,no_root_squash)" >>/etc/exports
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$cat  /etc/exports
/liruilong *(rw,sync,no_root_squash)
/tmp *(rw,sync,no_root_squash)
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$exportfs -avr
exporting *:/tmp
exporting *:/liruilong
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl apply -f pod_volunms-pv.yaml
persistentvolume/pv0003 created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl get pv -o wide
NAME     CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM   STORAGECLASS   REASON   AGE   VOLUMEMODE
pv0003   5Gi        RWO            Recycle          Available                                   16s   Filesystem

PV是有状态的对象,它有以下几种状态。
Available:空闲状态。
Bound:已经绑定到某个Pvc上。
Released:对应的PVC已经删除,但资源还没有被集群收回。
Failed: PV自动回收失败。

PVC的创建

如果某个Pod想申请某种类型的PV,则首先需要定义一个PersistentVolumeClaim (PVC)对象:

PVC是基于命名空间相互隔离的，不同命名空间的PVC相互隔离PVC通过accessModes和storage的约束关系来匹配PV，不需要显示定义，accessModes必须相同，storage必须小于等于。

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl get pvc
No resources found in liruilong-volume-create namespace.
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$vim pod_volumes-pvc.yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mypvc01
spec:
  accessModes:
    - ReadWriteOnce
  volumeMode: Filesystem
  resources:
    requests:
      storage: 4Gi
  #storageClassName: slow
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl apply  -f pod_volumes-pvc.yaml
persistentvolumeclaim/mypvc01 created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl get pvc -o wide
NAME      STATUS   VOLUME   CAPACITY   ACCESS MODES   STORAGECLASS   AGE   VOLUMEMODE
mypvc01   Bound    pv0003   5Gi        RWO                           10s   Filesystem
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$

storageClassName

storageClassName 用于控制那个PVC能和PV绑定，只有在storageClassName相同的情况下才去匹配storage和accessModes

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$vim  pod_volunms-pv.yaml

pod_volunms-pv.yaml

apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv0003
spec:
  capacity:
    storage: 5Gi
  volumeMode: Filesystem
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Recycle
  storageClassName: slow
  mountOptions:
    - hard
    - nfsvers=4.1
  nfs:
    path: /tmp
    server: vms81.liruilongs.github.io
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl apply  -f pod_volunms-pv.yaml
persistentvolume/pv0003 created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl get pv -A
NAME     CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM   STORAGECLASS   REASON   AGE
pv0003   5Gi        RWO            Recycle          Available           slow                    8s

pod_volumes-pvc.yaml

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mypvc01
spec:
  accessModes:
    - ReadWriteOnce
  volumeMode: Filesystem
  resources:
    requests:
      storage: 4Gi
  storageClassName: slow
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl get pvc -A
No resources found
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl apply  -f pod_volumes-pvc.yaml
persistentvolumeclaim/mypvc01 created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl get pvc -A
NAMESPACE                 NAME      STATUS   VOLUME   CAPACITY   ACCESS MODES   STORAGECLASS   AGE
liruilong-volume-create   mypvc01   Bound    pv0003   5Gi        RWO            slow           5s

使用持久性存储

在pod里面使用PVC

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: podvolumepvc
  name: podvolumepvc
spec:
  volumes:
  - name: volumes1
    persistentVolumeClaim:
      claimName: mypvc01
  containers:
  - image: Nginx
    name: podvolumehostpath
    resources: {}
    volumeMounts:
    - mountPath: /liruilong
      name: volumes1
    imagePullPolicy: IfNotPresent
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl apply  -f pod_volumespvc.yaml
pod/podvolumepvc created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl get pods -owide
NAME           READY   STATUS    RESTARTS   AGE   IP               NODE                         NOMINATED NODE   READINESS GATES
podvolumepvc   1/1     Running   0          15s   10.244.171.184   vms82.liruilongs.github.io   <none>           <none>
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl exec -it podvolumepvc -- sh
# ls
bin   dev                  docker-entrypoint.sh  home  lib64      media  opt   root  sbin  sys  usr
boot  docker-entrypoint.d  etc                   lib   liruilong  mnt    proc  run   srv   tmp  var
# cd liruilong
# ls
runc-process838092734
systemd-private-66344110bb03430193d445f816f4f4c4-chronyd.service-SzL7id
systemd-private-6cf1f72056ed4482a65bf89ec2a130a9-chronyd.service-5m7c2i
systemd-private-b1dc4ffda1d74bb3bec5ab11e5832635-chronyd.service-cPC3Bv
systemd-private-bb19f3d6802e46ab8dcb5b88a38b41b8-chronyd.service-cjnt04
#

pv回收策略

persistentVolumeReclaimPolicy: Recycle

策略 描述
Recycle –会删除数据 会生成一个pod回收数据,删除pvc之后，pv可复用,pv状态由Released变为Available
Retain–不回收数据 但是删除pvc之后，pv依然不可用，pv状态长期保持为 Released

会生成一个pod回收数据

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl get pv
NAME     CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                             STORAGECLASS   REASON   AGE
pv0003   5Gi        RWO            Recycle          Bound    liruilong-volume-create/mypvc01   slow                    131m
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl describe pv pv0003
..................
Events:
  Type    Reason       Age   From                         Message
  ----    ------       ----  ----                         -------
  Normal  RecyclerPod  53s   persistentvolume-controller  Recycler pod: Successfully assigned default/recycler-for-pv0003 to vms82.liruilongs.github.io
  Normal  RecyclerPod  51s   persistentvolume-controller  Recycler pod: Pulling image "busybox:1.27"
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl get pv
NAME     CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM   STORAGECLASS   REASON   AGE
pv0003   5Gi        RWO            Recycle          Available           slow                    136m
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$

动态卷供应storageClass

通过storageClass来动态处理PV的创建，管理员只需要创建好storageClass就可以了，用户创建PVC时会自动的创建PV和PVC。当创建 pvc 的时候，系统会通知 storageClass，storageClass 会从它所关联的分配器来获取后端存储类型，然后动态的创建一个 pv 出来和此 pvc 进行关联

storageClass 的工作流程

定义 storageClass 时必须要包含一个分配器(provisioner)，不同的分配器指定了动态创建 pv时使用什么后端存储。

分配器使用 aws 的 ebs 作为 pv 的后端存储

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: slow
provisioner: kubernetes.io/aws-ebs
parameters:
  type: io1
  iopsPerGB: "10"
  fsType: ext4

分配器使用 lvm 作为 pv 的后端存储

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: csi-lvm
provisioner: lvmplugin.csi.alibabacloud.com
parameters:
  vgName: volumegroup1
  fsType: ext4
  reclaimPolicy: Delete

使用 hostPath 作为 pv 的后端存储

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: csi-hostpath-sc
provisioner: hostpath.csi.k8s.io
reclaimPolicy: Delete
#volumeBindingMode: Immediate
volumeBindingMode: WaitForFirstConsumer
allowVolumeExpansion: true

上面 3 个例子里所使用的分配器中，有一些是 kubernetes 内置的分配器，比如kubernetes.io/aws-ebs，其他两个分配器不是 kubernetes 自带的。kubernetes 自带的分配器:

  • kubernetes.io/aws-ebs

  • kubernetes.io/gce-pd

  • kubernetes.io/glusterfs

  • kubernetes.io/cinder

  • kubernetes.io/vsphere-volume

  • kubernetes.io/rbd

  • kubernetes.io/quobyte

  • kubernetes.io/azure-disk

  • kubernetes.io/azure-file

  • kubernetes.io/portworx-volume

  • kubernetes.io/scaleio

  • kubernetes.io/storageos

  • kubernetes.io/no-provisioner

在动态创建 pv 的时候，根据使用不同的后端存储，应该选择一个合适的分配器。但是像lvmplugin.csi.alibabacloud.com 和 hostpath.csi.k8s.io 这样的分配器不是 kubernetes 自带的，称之为外部分配器，这些外部分配器由第三方提供，是通过自定义 CSIDriver(容器存储接口驱动)来实现的分配器。

所以整个流程就是，管理员创建storageClass时会通过provisioner 字段指定分配器。创建好storageClass之后，用户在定义pvc时需要通过.spec.storageClassName指定使用哪个storageClass。

利用 nfs 创建动态卷供应

创建一个目录/vdisk，并共享这个目录。

┌──[root@vms81.liruilongs.github.io]-[~]
└─$cat /etc/exports
/liruilong *(rw,sync,no_root_squash)
/tmp *(rw,sync,no_root_squash)
┌──[root@vms81.liruilongs.github.io]-[~]
└─$echo "/vdisk *(rw,sync,no_root_squash)" >>/etc/exports
┌──[root@vms81.liruilongs.github.io]-[~]
└─$exportfs  -avr
exporting *:/vdisk
exportfs: Failed to stat /vdisk: No such file or directory
exporting *:/tmp
exporting *:/liruilong
┌──[root@vms81.liruilongs.github.io]-[/]
└─$mkdir vdisks

因为 kubernetes 里，nfs 没有内置分配器，所以需要下载相关插件来创建 nfs 外部分配器。

插件包下载地址： https://github.com/kubernetes-incubator/external-storage.git

rbac.yaml 部署 rbac 权限。命名空间更换

apiVersion: v1
kind: ServiceAccount
metadata:
  name: nfs-client-provisioner
  # replace with namespace where provisioner is deployed
  namespace: liruilong-volume-create
---
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: liruilong-volume-create
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: liruilong-volume-create
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: liruilong-volume-create
subjects:
  - kind: ServiceAccount
    name: nfs-client-provisioner
    # replace with namespace where provisioner is deployed
    namespace: liruilong-volume-create
roleRef:
  kind: Role
  name: leader-locking-nfs-client-provisioner
  apiGroup: rbac.authorization.k8s.io

因为 nfs 分配器不是自带的，所以这里需要先把 nfs 分配器创建出来。

配置文件参数设置，1.20之后的版本都需要：- --feature-gates=RemoveSelfLink=false

┌──[root@vms81.liruilongs.github.io]-[/etc/kubernetes/manifests]
└─$pwd
/etc/kubernetes/manifests
┌──[root@vms81.liruilongs.github.io]-[/etc/kubernetes/manifests]
└─$head -n 20 kube-apiserver.yaml
apiVersion: v1
kind: Pod
metadata:
  annotations:
    kubeadm.kubernetes.io/kube-apiserver.advertise-address.endpoint: 192.168.26.81:6443
  creationTimestamp: null
  labels:
    component: kube-apiserver
    tier: control-plane
  name: kube-apiserver
  namespace: kube-system
spec:
  containers:
  - command:
    - kube-apiserver
    - --advertise-address=192.168.26.81
    - --feature-gates=RemoveSelfLink=false
    - --allow-privileged=true
    - --authorization-mode=Node,RBAC
    - --client-ca-file=/etc/kubernetes/pki/ca.crt
┌──[root@vms81.liruilongs.github.io]-[/etc/kubernetes/manifests]
└─$

deployment.yaml

  1. 因为当前是在命名空间 liruilong-volume-create里的，所以要把 namespace 的值改为 liruilong-volume-create

  2. image 后面的镜像需要提前在所有节点上 pull下来，并修改镜像下载策略

  3. env字段里，PROVISIONER_NAME用于指定分配器的名字，这里是 fuseim.pri/ifs，NFS_SERVER 和 NFS_PATH分别指定这个分配器所使用的存储信息。

  4. 在 volumes 里的 server 和 path 里指定共享服务器和目录

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nfs-client-provisioner
  labels:
    app: nfs-client-provisioner
  # replace with namespace where provisioner is deployed
  namespace: liruilong-volume-create
spec:
  replicas: 1
  strategy:
    type: Recreate
  selector:
    matchLabels:
      app: nfs-client-provisioner
  template:
    metadata:
      labels:
        app: nfs-client-provisioner
    spec:
      serviceAccountName: nfs-client-provisioner
      containers:
        - name: nfs-client-provisioner
          image: quay.io/external_storage/nfs-client-provisioner:latest
          imagePullPolicy: IfNotPresent
          volumeMounts:
            - name: nfs-client-root
              mountPath: /persistentvolumes
          env:
            - name: PROVISIONER_NAME
              value: fuseim.pri/ifs
            - name: NFS_SERVER
              value: 192.168.26.81
            - name: NFS_PATH
              value: /vdisk
      volumes:
        - name: nfs-client-root
          nfs:
            server: 192.168.26.81
            path: /vdisk

部署 nfs 分配器,查看 pod 的运行情况

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create/nfsdy]
└─$kubectl apply  -f deployment.yaml
deployment.apps/nfs-client-provisioner created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create/nfsdy]
└─$kubectl  get pods
NAME                                      READY   STATUS    RESTARTS   AGE
nfs-client-provisioner-65b5569d76-cz6hh   1/1     Running   0          73s
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create/nfsdy]
└─$

创建了 nfs 分配器之后，下面开始创建一个使用这个分配器的 storageClass。

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create/nfsdy]
└─$kubectl get sc
No resources found
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create/nfsdy]
└─$kubectl apply -f class.yaml
storageclass.storage.k8s.io/managed-nfs-storage created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create/nfsdy]
└─$kubectl get sc
NAME                  PROVISIONER      RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE
managed-nfs-storage   fuseim.pri/ifs   Delete          Immediate           false                  3s

class.yaml

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: managed-nfs-storage
provisioner: fuseim.pri/ifs # or choose another name, must match deployment's env PROVISIONER_NAME'
parameters:
  archiveOnDelete: "false"

这里 provisioner 的值 fuseim.pri/ifs 是由 deployment.yaml文件里指定的分配器的名字，这
个 yaml 文件的意思是创建一个名字是managed-nfs-storage的 storageClass，使用名字为fuseim.pri/ifs的分配器。

下面开始创建 pvc

pvc_nfs.yaml

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: pvc-nfs
spec:
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 20Mi
  storageClassName: "managed-nfs-storage"
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl  apply  -f ./pvc_nfs.yaml
persistentvolumeclaim/pvc-nfs created

查看创建信息

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl get pods
NAME                                      READY   STATUS    RESTARTS   AGE
nfs-client-provisioner-65b5569d76-7k6gm   1/1     Running   0          35s
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl get sc
NAME                  PROVISIONER      RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE
managed-nfs-storage   fuseim.pri/ifs   Delete          Immediate           false                  30s
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl get pvc
NAME      STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS          AGE
pvc-nfs   Bound    pvc-b12e988a-8b55-4d48-87cf-998500df16f8   20Mi       RWX            managed-nfs-storage   28s
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create/nfsdy]
└─$kubectl get pv
NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                             STORAGECLASS          REASON   AGE
pvc-b12e988a-8b55-4d48-87cf-998500df16f8   20Mi       RWX            Delete           Bound    liruilong-volume-create/pvc-nfs   managed-nfs-storage            126m
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create/nfsdy]
└─$

使用声明的PVC

pod_storageclass.yaml

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: podvolumepvc
  name: podvolumepvc
spec:
  volumes:
  - name: volumes1
    persistentVolumeClaim:
      claimName: pvc-nfs
  containers:
  - image: nginx
    name: podvolumehostpath
    resources: {}
    volumeMounts:
    - mountPath: /liruilong
      name: volumes1
    imagePullPolicy: IfNotPresent
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl apply  -f pod_storageclass.yaml
pod/podvolumepvc created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl get pods
NAME                                      READY   STATUS    RESTARTS   AGE
nfs-client-provisioner-65b5569d76-7k6gm   1/1     Running   0          140m
podvolumepvc                              1/1     Running   0          7s
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-volume-create]
└─$kubectl describe pods podvolumepvc | grep -A 4 Volumes:
Volumes:
  volumes1:
    Type:       PersistentVolumeClaim (a reference to a PersistentVolumeClaim in the same namespace)
    ClaimName:  pvc-nfs
    ReadOnly:   false

其他的数据卷类型

gcePersistentDisk

使用这种类型的Volume表示使用谷歌公有云提供的永久磁盘(PersistentDisk, PD)存放Volume的数据,它与emptyDir不同, PD上的内容会被永久存,当Pod被删除时, PD只是被卸载(Unmount),但不会被删除。需要注意是,你需要先创建一个永久磁盘(PD),才能使用gcePersistentDisk.

awsElasticBlockStore

与GCE类似,该类型的Volume使用亚马逊公有云提供的EBS Volume存储数据,需要先创建一个EBS Volume才能使用awsElasticBlockStore.

关于 Kubernetes中Volume的一些笔记


原文始发于微信公众号（山河已无恙）：关于 Kubernetes中Volume的一些笔记

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