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Kubernetes学习(rancher-local-path-provisioner)

kubernetes提供的local path给持久化提供了相当大的便利, 但有一个问题是, 每次都需要手动提前在机器上创建相应的目录来做为被调度应用的持久化目录, 不是很方便, 有没有办法可以自动创建呢?

对于rancher平台,rancher也提供了相应的工具local-path-provisioner

使用

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apiVersion: v1
kind: Namespace
metadata:
name: local-path-storage
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: local-path-provisioner-service-account
namespace: local-path-storage
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
name: local-path-provisioner-role
rules:
- apiGroups: [""]
resources: ["nodes", "persistentvolumeclaims"]
verbs: ["get", "list", "watch"]
- apiGroups: [""]
resources: ["endpoints", "persistentvolumes", "pods"]
verbs: ["*"]
- apiGroups: [""]
resources: ["events"]
verbs: ["create", "patch"]
- apiGroups: ["storage.k8s.io"]
resources: ["storageclasses"]
verbs: ["get", "list", "watch"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: local-path-provisioner-bind
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: local-path-provisioner-role
subjects:
- kind: ServiceAccount
name: local-path-provisioner-service-account
namespace: local-path-storage
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: local-path-provisioner
namespace: local-path-storage
spec:
replicas: 1
selector:
matchLabels:
app: local-path-provisioner
template:
metadata:
labels:
app: local-path-provisioner
spec:
serviceAccountName: local-path-provisioner-service-account
containers:
- name: local-path-provisioner
image: rancher/local-path-provisioner:v0.0.14
imagePullPolicy: IfNotPresent
command:
- local-path-provisioner
- --debug
- start
- --config
- /etc/config/config.json
volumeMounts:
- name: config-volume
mountPath: /etc/config/
env:
- name: POD_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
volumes:
- name: config-volume
configMap:
name: local-path-config
---
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
name: local-path
provisioner: rancher.io/local-path
volumeBindingMode: WaitForFirstConsumer
reclaimPolicy: Delete
---
kind: ConfigMap
apiVersion: v1
metadata:
name: local-path-config
namespace: local-path-storage
data:
config.json: |-
{
"nodePathMap":[
{
"node":"DEFAULT_PATH_FOR_NON_LISTED_NODES",
"paths":["/data"]
}
]
}
setup: |-
#!/bin/sh
path=$1
mkdir -m 0777 -p ${path}
teardown: |-
#!/bin/sh
path=$1
rm -rf ${path}

yaml文件几乎可以不用动直接部署, 部署之后在集群中就会出现一个名为local-path的storeclass

这样,如果一个应用需要使用某台机器的本地目录做为持久化,需要二步操作

  1. 调度到这台机器上
  2. 使用pvc时指定storeclass为local-path

使用官方的例子

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apiVersion: v1
kind: Pod
metadata:
name: volume-test
namespace: default
spec:
containers:
- name: volume-test
image: nginx:stable-alpine
imagePullPolicy: IfNotPresent
volumeMounts:
- name: volv
mountPath: /data
ports:
- containerPort: 80
volumes:
- name: volv
persistentVolumeClaim:
claimName: local-path-pvc
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: local-path-pvc
namespace: default
spec:
accessModes:
- ReadWriteOnce
storageClassName: local-path # 指定sc
resources:
requests:
storage: 2Gi

kubectl apply -f

查看pv/pvc绑定情况

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$ kubectl get pv
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pvc-bc3117d9-c6d3-11e8-b36d-7a42907dda78 2Gi RWO Delete Bound default/local-path-pvc local-path 4s

$ kubectl get pvc
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
local-path-pvc Bound pvc-bc3117d9-c6d3-11e8-b36d-7a42907dda78 2Gi RWO local-path 16s

$ kubectl get pod
NAME READY STATUS RESTARTS AGE
volume-test 1/1 Running 0 3s

可以看到pv/pvc绑定成功了且应用的持久化目录在机器的/data目录下

配置文件

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kind: ConfigMap
apiVersion: v1
metadata:
name: local-path-config
namespace: local-path-storage
data:
config.json: |-
{
"nodePathMap":[
{
"node":"DEFAULT_PATH_FOR_NON_LISTED_NODES",
"paths":["/data"]
},
{
"node":"yasker-lp-dev1",
"paths":["/opt/local-path-provisioner", "/data1"]
},
{
"node":"yasker-lp-dev3",
"paths":[]
}
]
}
setup: |-
#!/bin/sh
path=$1
mkdir -m 0777 -p ${path}
teardown: |-
#!/bin/sh
path=$1
rm -rf ${path}

配置里是可以对不同的node指定不同的path, 如果未指定node, 则使用默认值

不足

通过这种方式我们可以不再需要生成pv, 直接使用pvc即可,但还是有些不足的地方,目前还不支持对持久化目录做到可以限制使用大小

另外,kubernetes sig也出了一个对于local volume的工具sig-storage-local-static-provisioner相对来说更加通用,但是也有不足的地方,感兴趣的可以参考

参考文章:

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