kubernetes污点与容忍

著作:行癫 <盗版必究> ------ ## 一:污点与容忍 ​ 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 #### 1.将节点设置为污点 ```shell [root@master yaml]# kubectl taint node node-2 key=value:NoSchedule node/node-2 tainted ``` 查看污点: ```shell [root@master yaml]# kubectl describe node node-1 | grep Taint Taints: ``` #### 2.去除节点污点 ```shell [root@master yaml]# kubectl taint node node-2 key=value:NoSchedule- node/node-2 untainted ``` #### 3.污点分类 ​ 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 ​ NoExecute:新的不能容忍的pod不能调度过来,老的pod也会被驱逐 ​ PreferNoScheduler:表示尽量不调度到污点节点中去 #### 4.使用 ​ 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: ```shell [root@master yaml]# kubectl taint node node-2 key=value:NoSchedule node/node-2 tainted [root@master yaml]# cat b.yaml apiVersion: v1 kind: Pod metadata: name: sss spec: affinity: nodeAffinity: requiredDuringSchedulingIgnoredDuringExecution: nodeSelectorTerms: - matchExpressions: - key: app operator: In values: - myapp containers: - name: with-node-affinity image: daocloud.io/library/nginx:latest 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 [root@master yaml]# cat b.yaml apiVersion: v1 kind: Pod metadata: name: sss-1 spec: affinity: nodeAffinity: requiredDuringSchedulingIgnoredDuringExecution: nodeSelectorTerms: - matchExpressions: - key: app operator: In values: - myapp containers: - name: with-node-affinity image: daocloud.io/library/nginx:latest tolerations: - key: "key" operator: "Equal" value: "value" effect: "NoSchedule" ``` 结果:旧的调度失败,新的调度成功 ```shell [root@master yaml]# kubectl get pod -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES sss 0/1 Pending 0 3m2s sss-1 1/1 Running 0 7s 10.244.2.9 node-2 ``` 注意: ​ tolerations: #添加容忍策略 ​ \- key: "key1" #对应我们添加节点的变量名 ​ operator: "Equal" #操作符 ​ value: "value" #容忍的值 key1=value对应 ​ 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 ​ operator值是Exists,则value属性可以忽略 ​ operator值是Equal,则表示key与value之间的关系是等于 ​ operator不指定,则默认为Equal