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Kubernetes节点与 Pod 亲和性

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一、节点亲和性策略介绍

pod.spec.nodeAffinity

  • preferredDuringSchedulingIgnoredDuringExecution:软策略

  • requiredDuringSchedulingIgnoredDuringExecution:硬策略

preferred:首选,较喜欢 required:需要,必修

键值运算关系:

  • In:label 的值在某个列表中

  • NotIn:label 的值不在某个列表中

  • Gt:label 的值大于某个值

  • Lt:label 的值小于某个值

  • Exists:某个 label 存在

  • DoesNotExist:某个 label 不存在

二、节点与Pod硬亲和性

requiredDuringSchedulingIgnoredDuringExecution

#创建pod的模板yaml文件 vim affinity.yaml apiVersion: v1 kind: Pod metadata: name: affinity labels: app: node-affinity-pod spec: containers: - name: with-node-affinity image: docker.io/nginx affinity: nodeAffinity: requiredDuringSchedulingIgnoredDuringExecution: nodeSelectorTerms: - matchExpressions: - key: kubernetes.io/hostname operator: NotIn values: - node-1

通过修改 Pod 名称的方式多创建几个 Pod 查看结果:
119.png

这个时候,我们将 operator 修改为 “In” ,node-1 修改为 node-3,

vim affinity.yaml apiVersion: v1 kind: Pod metadata: name: affinity-3 labels: app: node-affinity-pod spec: containers: - name: with-node-affinity image: docker.io/nginx affinity: nodeAffinity: requiredDuringSchedulingIgnoredDuringExecution: nodeSelectorTerms: - matchExpressions: - key: kubernetes.io/hostname operator: In values: - node-3

查看下结果:
120.png

这个时候可以看到,我们新创建的 Pod 一直处于 Pending 的状态,这是因为我们没有Node-3这个节点,且采用的是硬亲和性策略的原因所导致的。

三、节点与Pod软亲和性

preferredDuringSchedulingIgnoredDuringExecution
为了解决上述因为硬亲和性创建Pod不成功的问题,我们通过设置软亲和性策略后再次创建一个pod affinity-pod-a测试。

vim affinity-1.yaml apiVersion: v1 kind: Pod metadata: name: affinity-a labels: app: node-affinity-pod-a spec: containers: - name: with-node-affinity-a image: docker.io/nginx affinity: nodeAffinity: preferredDuringSchedulingIgnoredDuringExecution: - weight: 1 preference: matchExpressions: - key: kubernetes.io/hostname operator: In values: - node-3

我们没有 node-3 节点,这个时候我们创建看一下:

121.png

我们再将 node-3 修改为 node-1 看一下:

122.png

通过实验我们得出关于节点与pod亲和力策略

  • 硬限制是:我必须在某个节点或我必须不在某个节点。

  • 软限制是:我想在某个节点或我不想在某个节点,实在不行,我也可以将就。

​软硬限制结合策略
策略优先级:先满足硬限制,然后满足软限制

软硬限制可以结合使用,先满足硬限制,然后满足软限制= apiVersion: v1 kind: Pod metadata: name: affinity labels: app: node-affinity-pod spec: containers: - name: with-node-affinity image: docker.io/nginx affinity: nodeAffinity: requiredDuringSchedulingIgnoredDuringExecution: nodeSelectorTerms: - matchExpressions: - key: kubernetes.io/hostname operator: NotIn values: - node-2 preferredDuringSchedulingIgnoredDuringExecution: - weight: 1 preference: matchExpressions: - key: source operator: In values: - zutuanxue_com

四、Pod 亲和性

​pod.spec.affinity.podAffinity/podAntiAffinity

  • preferredDuringSchedulingIgnoredDuringExecution:软策略

  • requiredDuringSchedulingIgnoredDuringExecution:硬策略

podAffinity: pod之间亲和,pod在同一网段 podAntiAffinity:pod之间反亲和,pod在不同网段

4.1、pod亲和性

vim test-pod.yaml apiVersion: v1 kind: Pod metadata: name: pod-1 labels: app: pod-1 spec: containers: - name: pod-1 image: docker.io/busybox command: [ "/bin/sh", "-c", "sleep 600s" ] #-----------------------------# 分割线 #--------------------------------------# vim affinity-pod.yaml apiVersion: v1 kind: Pod metadata: name: pod-3 labels: app: pod-3 spec: containers: - name: pod-3 image: docker.io/nginx affinity: podAffinity: requiredDuringSchedulingIgnoredDuringExecution: - labelSelector: matchExpressions: - key: app operator: In values: - pod-1 topologyKey: kubernetes.io/hostname

​我们来看一下结果:

123.png

五、关于亲和性总结

调度策略 匹配标签 操作符 拓扑域支持 调度目标
nodeAffinity 主机 In, NotIn, Exists,DoesNotExist, Gt, Lt 指定主机
podAffinity POD In, NotIn, Exists,DoesNotExist POD与指定POD同一拓扑域
podAnitAffinity POD In, NotIn, Exists,DoesNotExist POD与指定POD不在同一拓扑域
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