PersistentVolumeClaim
PVC 概述
- Persistent Volume Claim 持久卷申请，简称 PVC，名称空间级别资源
- PVC 由用户使用，由用户定义出存储消费需求，而后根据需求条件与现有各 PV 进行匹配检测，找出一个最佳的使用，并与之绑定，最终交给 Pod 来使用。
- Pod 是通过 PVC 将数据保存至 PV，PV 再保存至真实存储
- 一个 PVC 只能绑定(bound)一个 PV
- 另外，PV 与 PVC 二者要么都不属于任何StorageClass资源，要么属于同一个StorageClass资源，才能进行绑定
PVC Explain
定义PVC时，用户可通过访问模式（accessModes）、数据源（dataSource）、存储资源空间需求和限制（resources）、存储类、标签选择器、卷模型和卷名称等匹配标准来筛选集群上的PV资源
- 其中 resources 和 accessModes是最重的筛选标准
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: pvc-tmp
namespace: default
spec:
volumeName: pv-tmp # 直接指定要绑定的PV资源的名称(一般不定义，而是由定义的各种维度进行动态筛选)
accessModes:
- ReadWriteOnce # PVC的访问模式；它同样支持RWO、RWX和ROX三种模式
resources: # 声明使用的存储空间的最小值和最大值(以选出合适的PV)；目前，PVC的资源限定仅支持空间大小一个维度
requests:
storage: 80GiaccessModes
- 被筛选的PV也要同样支持此处定义的访问模式
PersistentVolumeClaim.spec.accessModes
dataSource
-
用于从指定的数据源恢复该PVC卷，它目前支持的数据源包括一个现在卷快照对象（snapshot.storage.k8s.io/VolumeSnapshot）、一个既有PVC对象（PersistentVolumeClaim）或一个既有的用于数据转存的自定义资源对象（resource/object）
-
PersistentVolumeClaim.spec.dataSource
selector
-
筛选PV时额外使用的标签选择器（matchLabels）或匹配条件表达式（matchExpressions）
-
PersistentVolumeClaim.spec.selector
storageClassName
-
该PVC资源隶属的存储类资源名称；指定了存储类资源的PVC仅能在同一个存储类下筛选PV资源，否则，就只能从所有不具有存储类的PV中进行筛选
-
PersistentVolumeClaim.spec.storageClassName
volumeMode
- 卷模型，用于指定此卷可被用作文件系统还是裸格式的块设备；默认值为Filesystem；
- 被筛选的PV也要同样支持相同的卷模型
PersistentVolumeClaim.spec.volumeMode
PVC Example
创建 PVC
验证 pv
- 需事先具有PV
# kubectl get pv
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pv-nfs-001 5Gi RWO Retain Available 4m22s
pv-nfs-002 5Gi RWX Retain Available 4m22s
pv-nfs-003 10Gi RWX Retain Available 4m22syaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: pvc-demo-001
spec:
accessModes: ["ReadWriteMany"]
volumeMode: Filesystem
resources:
requests:
storage: 3Gi
limits:
storage: 10Gi
selector: # 只有与此处选择器定义所匹配的pv才能够被匹配
matchLabels:
usedof: "redisdata"验证
- pv-nfs-002 和 pv-nfs-003 都满足RWX，但会更倾向于接近
PersistentVolumeClaim.spec.resources.requests中定义的请求值进行匹配 - 如果没有合适的PV来满足PVC，PVC将不会与任何PV建立绑定关系
# kubectl get pvc
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
pvc-demo-001 Bound pv-nfs-002 5Gi RWX 3sPod 中使用 PVC
验证 PVC
# kubectl describe pvc pvc-demo-001
Name: pvc-demo-001
Namespace: default
StorageClass:
Status: Bound
Volume: pv-nfs-002
Labels: <none>
Annotations: pv.kubernetes.io/bind-completed: yes
pv.kubernetes.io/bound-by-controller: yes
Finalizers: [kubernetes.io/pvc-protection]
Capacity: 5Gi
Access Modes: RWX
VolumeMode: Filesystem
Used By: <none>
Events: <none>
# 对应的PV
# kubectl describe pv pv-nfs-002
Name: pv-nfs-002
Labels: usedof=redisdata
Annotations: pv.kubernetes.io/bound-by-controller: yes
Finalizers: [kubernetes.io/pv-protection]
StorageClass:
Status: Bound
Claim: default/pvc-demo-001
Reclaim Policy: Retain
Access Modes: RWX
VolumeMode: Filesystem
Capacity: 5Gi
Node Affinity: <none>
Message:
Source:
Type: NFS (an NFS mount that lasts the lifetime of a pod)
Server: 10.0.0.8
Path: /data/nfs/redis002
ReadOnly: false
Events: <none>yaml
- 注：Pod 只能调用与自己在同一名称空间中的 PVC
apiVersion: v1
kind: Pod
metadata:
name: volumes-pvc-demo
namespace: default
spec:
containers:
- name: redis
image: redis:alpine
imagePullPolicy: IfNotPresent
securityContext:
runAsUser: 1688 # 因为此处PVC对应PV所关联的是nfs，所以需要定义在nfs挂载目录中有读写权限的用户
ports:
- containerPort: 6379
name: redisport
volumeMounts:
- mountPath: /data
name: redis-nfs-vol
volumes:
- name: redis-nfs-vol
persistentVolumeClaim:
claimName: pvc-demo-001验证
# kubectl describe pod volumes-pvc-demo
...
Containers:
...
Mounts:
/data from redis-nfs-vol (rw)
...
Volumes:
redis-nfs-vol:
Type: PersistentVolumeClaim (a reference to a PersistentVolumeClaim in the same namespace)
ClaimName: pvc-demo-001
ReadOnly: false
...
# 写入数据测试
# kubectl exec -it volumes-pvc-demo -- sh
/data $ redis-cli -h 127.0.0.1
127.0.0.1:6379> set mykey jamesazheng
OK
127.0.0.1:6379> get mykey
"jamesazheng"
127.0.0.1:6379> bgsave
Background saving started
127.0.0.1:6379>
/data $ ls /data/ -l
total 4
-rw-r--r-- 1 1688 nobody 116 Dec 28 04:17 dump.rdb
# nfs端生成的数据
# ls -l /data/nfs/redis002/
total 4
-rw-r--r-- 1 redis nobody 116 Dec 28 12:17 dump.rdb
# 删除pod重建后数据仍然会保留
# kubectl exec -it volumes-pvc-demo -- sh
/data $ redis-cli -h 127.0.0.1
127.0.0.1:6379> get mykey
"jamesazheng"卸载PVC
实现 PV / PVC
- Jenkins数据实现持久化；NFS 作为集群外存储，PV 调用 NFS
相关文件
# pwd
/data/yaml/jenkins
# ll
total 20
drwxr-xr-x 2 root root 4096 Jul 16 16:21 ./
drwxr-xr-x 7 root root 4096 Jul 16 16:11 ../
-rw-r--r-- 1 root root 1583 Jul 16 16:11 jenkins-deployment.yaml
-rw-r--r-- 1 root root 487 Jul 16 16:11 jenkins-pvc.yaml
-rw-r--r-- 1 root root 531 Jul 16 16:11 jenkins-pv.yaml准备 NFS
- 安装过程省略
# 创建共享目录
# mkdir -p /nfs_data/jenkins/{jenkins-data,jenkins-root}
# 定义共享目录
# vim /etc/exports
...
/nfs_data/jenkins/ *(rw,no_root_squash)
# 重载配置文件
# exportfs -r
# 查看共享结果
# showmount -e 10.0.0.103
Export list for 10.0.0.103:
/nfs_data/jenkins/ *准备 namespace
# vim /data/yaml/jenkins/jenkins-ns.yaml
apiVersion: v1
kind: Namespace
metadata:
name: jenkins验证
# kubectl apply -f /data/yaml/jenkins/jenkins-ns.yaml
namespace/jenkins created
# kubectl get ns
NAME STATUS AGE
jenkins Active 2s
...准备 PV
# vim /data/yaml/jenkins/jenkins-pv.yaml
apiVersion: v1
kind: PersistentVolume
metadata:
name: jenkins-data-pv
labels:
type: jenkins-data-pv
namespace: jenkins
spec:
capacity:
storage: 100Gi
accessModes:
- ReadWriteOnce
persistentVolumeReclaimPolicy: Retain
nfs:
path: "/nfs_data/jenkins/jenkins-data"
server: 10.0.0.103
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: jenkins-root-pv
labels:
type: jenkins-root-pv
namespace: jenkins
spec:
capacity:
storage: 100Gi
accessModes:
- ReadWriteOnce
persistentVolumeReclaimPolicy: Retain
nfs:
path: "/nfs_data/jenkins/jenkins-root"
server: 10.0.0.103验证
# kubectl apply -f jenkins-pv.yaml
persistentvolume/jenkins-data-pv created
persistentvolume/jenkins-root-pv created
# STATUS 一定要是 Available
# kubectl get pv
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
jenkins-data-pv 100Gi RWO Retain Available 3s
jenkins-root-pv 100Gi RWO Retain Available 3s准备 PVC
# vim /data/yaml/jenkins/jenkins-pvc.yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: jenkins-data-pvc
namespace: jenkins
spec:
volumeName: jenkins-data-pv
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 80Gi
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: jenkins-root-pvc
namespace: jenkins
spec:
volumeName: jenkins-root-pv
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 80Gi验证
# kubectl apply -f /data/yaml/jenkins/jenkins-pvc.yaml
persistentvolumeclaim/jenkins-data-pvc created
persistentvolumeclaim/jenkins-root-pvc created
# STATUS 一定要是 Bound
# kubectl get pv
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
jenkins-data-pv 100Gi RWO Retain Bound jenkins/jenkins-data-pvc 113s
jenkins-root-pv 100Gi RWO Retain Bound jenkins/jenkins-root-pvc 113s
# STATUS 一定要是 Bound
# kubectl get pvc -n jenkins
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
jenkins-data-pvc Bound jenkins-data-pv 100Gi RWO 17s
jenkins-root-pvc Bound jenkins-root-pv 100Gi RWO 17s准备 deployment
# vim /data/yaml/jenkins/jenkins-deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: jenkins-deployment
namespace: jenkins
spec:
replicas: 1
selector:
matchLabels:
app: jenkins
template:
metadata:
labels:
app: jenkins
spec:
restartPolicy: Always
containers:
- name: jenkins-server
image: jenkins-2.303.3-jdk-8u333:1.0
imagePullPolicy: IfNotPresent
ports:
- containerPort: 8080
name: jenkins-server
protocol: TCP
resources:
requests:
cpu: 512m
memory: 512Mi
limits:
cpu: 1
memory: 1024Mi
volumeMounts:
- mountPath: "/jenkins/jenkins-data/" # 结尾 / 加与不加效果都一样，都是将整个目录下的所有挂载至存储
name: jenkins-data # 调用卷名称（相当于调用PVC的别名）
- mountPath: "/root/.jenkins/"
name: jenkins-root
volumes:
- name: jenkins-data # 定义卷名称（相当于给PVC起别名）
persistentVolumeClaim:
claimName: jenkins-data-pvc # 指定pvc的name，需等于PersistentVolumeClaim.metadata.name
- name: jenkins-root
persistentVolumeClaim:
claimName: jenkins-root-pvc
---
kind: Service
apiVersion: v1
metadata:
labels:
app: jenkins-service
name: jenkins-service
namespace: jenkins
spec:
type: NodePort
ports:
- name: jenkins-server
port: 8080
protocol: TCP
targetPort: 8080
nodePort: 30080
selector:
app: jenkins验证
# kubectl apply -f /data/yaml/jenkins/jenkins-deployment.yaml
deployment.apps/jenkins-deployment created
service/jenkins-service created
# kubectl get pod -n jenkins -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
jenkins-deployment-64d5b67576-gqd5z 1/1 Running 0 9m31s 10.10.1.147 k8s-work-1 <none> <none>测试
root@nfs:/nfs_data/jenkins# ls jenkins-data/
bootstrap images 'Main$FileAndDescription.class' robots.txt
ColorFormatter.class JNLPMain.class Main.class scripts
css jsbundles 'MainDialog$1$1.class' WEB-INF
executable 'LogFileOutputStream$1.class' 'MainDialog$1.class' winstone.jar
favicon.ico 'LogFileOutputStream$2.class' MainDialog.class
help LogFileOutputStream.class META-INF
root@nfs:/nfs_data/jenkins# ls jenkins-root/
config.xml jobs plugins updates
hudson.model.UpdateCenter.xml logs secret.key userContent
identity.key.enc nodeMonitors.xml secret.key.not-so-secret users
jenkins.telemetry.Correlator.xml nodes secretsceph
rbd example
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: pvc-sc-rbd-demo
namespace: default
spec:
accessModes: ["ReadWriteOnce"]
volumeMode: Filesystem
resources:
requests:
storage: 3Gi
limits:
storage: 10Gi
storageClassName: fast-rbdcephfs example
apiVersion: v1
kind: Pod
metadata:
name: volumes-cephfs-demo
spec:
containers:
- name: redis
image: redis:alpine
volumeMounts:
- mountPath: "/data"
name: redis-cephfs-vol
volumes:
- name: redis-cephfs-vol
cephfs:
monitors:
- 172.29.200.1:6789
- 172.29.200.2:6789
- 172.29.200.3:6789
path: /kube/namespaces/default/redis1
user: fsclient
secretFile: "/etc/ceph/fsclient.key"
readOnly: false