124 lines
3.5 KiB
Markdown
124 lines
3.5 KiB
Markdown
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<h1><center>kubernetes污点与容忍</center></h1>
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著作：行癫 <盗版必究>
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------
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## 一：污点与容忍
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对于nodeAffinity无论是硬策略还是软策略方式，都是调度POD到预期节点上，而Taints恰好与之相反，如果一个节点标记为Taints ，除非 POD 也被标识为可以容忍污点节点，否则该 Taints 节点不会被调度pod；比如用户希望把 Master 节点保留给 Kubernetes 系统组件使用，或者把一组具有特殊资源预留给某些 POD，则污点就很有用了，POD 不会再被调度到 taint 标记过的节点
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#### 1.将节点设置为污点
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```shell
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[root@master yaml]# kubectl taint node node-2 key=value:NoSchedule
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node/node-2 tainted
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```
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查看污点：
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```shell
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[root@master yaml]# kubectl describe node node-1 | grep Taint
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Taints: <none>
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```
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#### 2.去除节点污点
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```shell
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[root@master yaml]# kubectl taint node node-2 key=value:NoSchedule-
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node/node-2 untainted
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```
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#### 3.污点分类
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NoSchedule:新的不能容忍的pod不能再调度过来，但是之前运行在node节点中的Pod不受影响
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NoExecute:新的不能容忍的pod不能调度过来，老的pod也会被驱逐
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PreferNoScheduler:表示尽量不调度到污点节点中去
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#### 4.使用
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如果仍然希望某个 POD 调度到 taint 节点上，则必须在 Spec 中做出Toleration定义，才能调度到该节点，举例如下:
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```shell
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[root@master yaml]# kubectl taint node node-2 key=value:NoSchedule
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node/node-2 tainted
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[root@master yaml]# cat b.yaml
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apiVersion: v1
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kind: Pod
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metadata:
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name: sss
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spec:
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affinity:
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nodeAffinity:
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requiredDuringSchedulingIgnoredDuringExecution:
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nodeSelectorTerms:
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- matchExpressions:
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- key: app
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operator: In
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values:
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- myapp
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containers:
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- name: with-node-affinity
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image: daocloud.io/library/nginx:latest
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注意:node-2节点设置为污点,所以label定义到node-2,但是因为有污点所以调度失败,以下是新的yaml文件
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[root@master yaml]# cat b.yaml
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apiVersion: v1
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kind: Pod
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metadata:
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name: sss-1
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spec:
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affinity:
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nodeAffinity:
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requiredDuringSchedulingIgnoredDuringExecution:
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nodeSelectorTerms:
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- matchExpressions:
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- key: app
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operator: In
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values:
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- myapp
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containers:
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- name: with-node-affinity
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image: daocloud.io/library/nginx:latest
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tolerations:
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- key: "key"
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operator: "Equal"
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value: "value"
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effect: "NoSchedule"
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```
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结果：旧的调度失败,新的调度成功
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```shell
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[root@master yaml]# kubectl get pod -o wide
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NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
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sss 0/1 Pending 0 3m2s <none> <none> <none> <none>
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sss-1 1/1 Running 0 7s 10.244.2.9 node-2 <none> <none>
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```
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注意：
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tolerations: #添加容忍策略
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\- key: "key1" #对应我们添加节点的变量名
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operator: "Equal" #操作符
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value: "value" #容忍的值 key1=value对应
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effect: NoExecute #添加容忍的规则，这里必须和我们标记的五点规则相同
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operator值是Exists，则value属性可以忽略
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operator值是Equal，则表示key与value之间的关系是等于
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operator不指定，则默认为Equal
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