k8s实践6:pod应用数据存储解耦pv&&pvc

2023-09-09 01:26| 来源: 网络整理| 查看: 265

k8s实践6:pod应用数据存储解耦pv&&pvc 原创

am2012 2019-04-09 11:37:26 博主文章分类：k8s ©著作权

文章标签 kubernetes pv pvc 文章分类运维

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1.PV&&PVC基础概念

PersistentVolume(PV)是外部存储系统中的一块存储空间,管理员创建和维护.PV具有独立性,生命周期独立于Pod. PersistentVolumeClaim(PVC)是对PV的申请.PVC一般普通用户创建和维护. 需要为Pod分配资源时,用户创建一个PVC,指明存储资源的容量大小和访问模式,kubernetes会查找并提供满足条件的PV.

2.nfs部署

pv对接外部存储系统,这里是实验环境,对接nfs.生成环境,建议使用安全性高的分布式存储,ceph等.

nfs服务需要用到的软件 nfs-utils nfs主程序(rpc.nfsd,rbc.mountd) rpcbind rpc主程序

一些基础情况说明,现在整个集群环境3节点

kubectl get nodes NAME STATUS ROLES AGE VERSION k8s-node1 Ready 19d v1.15.5 k8s-node2 Ready 19d v1.15.5 k8s-node3 Ready 19d v1.15.5

其中k8s-node3剩余空间比较大(这个随便哪个节点都可以,根据自己喜好和空间),因此使用k8s-node3来存储数据.

k8s-node3上部署nfs

安装软件包

[root@k8s-node3 ~]# yum install -y nfs-utils rpcbind

启动服务设置开机启动并查看当前状态

[root@k8s-node3 ~]# systemctl start rpcbind &&systemctl enable rpcbind [root@k8s-node3 ~]# systemctl start nfs && systemctl enable nfs [root@k8s-node3 ~]# systemctl status rpcbind ● rpcbind.service - RPC bind service Loaded: loaded (/usr/lib/systemd/system/rpcbind.service; enabled; vendor preset: enabled) Active: active (running) since Mon 2019-11-25 02:54:03 EST; 37s ago Main PID: 17314 (rpcbind) CGroup: /system.slice/rpcbind.service └─17314 /sbin/rpcbind -w Nov 25 02:54:03 k8s-node3 systemd[1]: Starting RPC bind service... Nov 25 02:54:03 k8s-node3 systemd[1]: Started RPC bind service. [root@k8s-node3 ~]# systemctl status rpcbind ● rpcbind.service - RPC bind service Loaded: loaded (/usr/lib/systemd/system/rpcbind.service; enabled; vendor preset: enabled) Active: active (running) since Mon 2019-11-25 02:54:03 EST; 37s ago Main PID: 17314 (rpcbind) CGroup: /system.slice/rpcbind.service └─17314 /sbin/rpcbind -w Nov 25 02:54:03 k8s-node3 systemd[1]: Starting RPC bind service... Nov 25 02:54:03 k8s-node3 systemd[1]: Started RPC bind service. [root@k8s-node3 ~]# systemctl status nfs ● nfs-server.service - NFS server and services Loaded: loaded (/usr/lib/systemd/system/nfs-server.service; enabled; vendor preset: disabled) Active: active (exited) since Mon 2019-11-25 02:54:11 EST; 54s ago Main PID: 17405 (code=exited, status=0/SUCCESS) CGroup: /system.slice/nfs-server.service Nov 25 02:54:11 k8s-node3 systemd[1]: Starting NFS server and services... Nov 25 02:54:11 k8s-node3 systemd[1]: Started NFS server and services. 配置nfs服务端 /etc/exports是默认的nfs程序配置文件,默认为空加入配置 [root@k8s-node3 ~]# mkdir -p /mnt/data [root@k8s-node3 ~]# echo "/mnt/data 192.168.174.0/24(rw,no_root_squash,no_all_squash,sync)" >/etc/exports

重启rpcbind和nfs服务,检索nfs本机挂载情况

[root@k8s-node3 ~]# systemctl restart rpcbind && systemctl restart nfs [root@k8s-node3 ~]# showmount -e localhost Export list for localhost: /mnt/data 192.168.174.0/24

可能的报错

注意: 192.168.32.0/24(rw,no_root_squash,no_all_squash,sync) 中间不能有空格,切记,不然报错. 注意: 必须在所有node安装rpcbind并启动,确保nfs能正常挂载。否则报错: mount failed: exit status 32

nfs客户端配置

客户端也需要安装nfs-utils和rpcbind,同时只需要启动rpcbind.

yum install -y nfs-utils rpcbind

确保客户端能正常读取,见下

showmount -e k8s-node3 Export list for k8s-node3: /mnt/data 192.168.174.0/24

3.pv基础知识

创建pv

kubectl apply -f nfs-pv1.yaml persistentvolume/mypv1 created cat nfs-pv1.yaml apiVersion: v1 kind: PersistentVolume metadata: name: mypv1 spec: capacity: storage: 100Mi accessModes: - ReadWriteMany persistentVolumeReclaimPolicy: Retain storageClassName: nfs nfs: path: /mnt/data/pv1 server: 192.168.184.130

基础参数

capacity指定PV的容量 accessModes指定访问模式，支持的模式有: ReadWriteOnce 能以read-write模式mount到单个节点 ReadOnlyMany 能以read-only模式mount到多个节点 ReadWriteMany 能以read-write模式mount到多个节点节点其实就是pod,如果多个pod必须用ReadWriteMany persistentVolumeReclaimPolicy指定pv的回收策略 Retain 需要管理员收工回收,安全性最高 Recycle 清除PV中的数据，效果相当于执行rm -rf Delete 删除storage provider上对应的存储资源 storageClassName 指定PV的分类，PVC可以指定class申请相应的PV path: /mnt/data/pv1 指定nfs上对应的目录，需手动建立 kubectl get pv NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE mypv1 100Mi RWX Retain Available nfs 2m1s

基础参数

PV是有状态的资源对象，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，但资源还没有被回收 Failed：pv自动回收失败

4.pvc基础知识

创建pvc

kubectl apply -f nfs-pvc1.yml persistentvolumeclaim/mypvc1 created cat nfs-pvc1.yml apiVersion: v1 kind: PersistentVolumeClaim metadata: name: mypvc1 spec: accessModes: - ReadWriteMany resources: requests: storage: 50Mi storageClassName: nfs kubectl get pv,pvc NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE persistentvolume/mypv1 100Mi RWX Retain Bound default/mypvc1 nfs 4m50s NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE persistentvolumeclaim/mypvc1 Bound mypv1 100Mi RWX nfs 40s

注意:pvc使用之后,pv的状态已经变成Bound

5.pv和pvc是怎么对应上的呢?

上面测试的pv和pvc是通过指定 storageClassName: nfs 参数对应的. 如果不指定这个参数,会怎样呢？根据官方的描述: 用户创建一个PVC,指明存储资源的容量大小和访问模式,kubernetes会查找并提供满足条件的PV. 也就是说,pvc会根据自己的需求去申请合适的pv.

测试见下

cat nfs-pv-noname1.yaml apiVersion: v1 kind: PersistentVolume metadata: name: mypv-noname1 spec: capacity: storage: 100Mi accessModes: - ReadWriteMany persistentVolumeReclaimPolicy: Retain storageClassName: nfs: path: /mnt/data/pv1 server: 192.168.174.130 cat nfs-pv-noname2.yaml apiVersion: v1 kind: PersistentVolume metadata: name: mypv-noname2 spec: capacity: storage: 10Mi accessModes: - ReadWriteMany persistentVolumeReclaimPolicy: Retain storageClassName: nfs: path: /mnt/data/pv1 server: 192.168.174.130

pvc

cat nfs-pvc-noname1.yaml apiVersion: v1 kind: PersistentVolumeClaim metadata: name: mypvc-noname1 spec: accessModes: - ReadWriteMany resources: requests: storage: 10Mi storageClassName: cat nfs-pvc-noname2.yaml apiVersion: v1 kind: PersistentVolumeClaim metadata: name: mypvc-noname2 spec: accessModes: - ReadWriteMany resources: requests: storage: 50Mi storageClassName:

执行情况见下

[root@k8s-node1 pv_pvc]# kubectl get pv NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE mypv-noname1 100Mi RWX Retain Bound default/mypvc-noname2 4m51s mypv-noname2 10Mi RWX Retain Bound default/mypvc-noname1 4m17s mypv1 100Mi RWX Retain Bound default/mypvc1 nfs 15m [root@k8s-node1 pv_pvc]# kubectl get pvc NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE mypvc-noname1 Bound mypv-noname2 10Mi RWX 11s mypvc-noname2 Bound mypv-noname1 100Mi RWX 9s mypvc1 Bound mypv1 100Mi RWX nfs 11m [root@k8s-node1 pv_pvc]#

可以看到,不指定任何匹配参数的情况下,pvc自动申请使用匹配的pv.

注意:如果pv指定 storageClassName:参数,pvc不指定相对应的storageClassName:参数,pvc无法自动申请使用匹配该pv.比如上面的mypv1,无法被未指定对应名字和没有指定名字的pvc使用.

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