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@ -48,4 +48,6 @@ CKA证书的含金量如何？考不考这个证完全取决于个人，因为
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[CKA每日一题 - Day 4](./daily/004.html)
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[CKA每日一题 - Day 5](./daily/005.html)
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<JoinCKACommunity/>
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@ -46,10 +46,6 @@ spec:
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### 解析
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## 昨日解析
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**官网中调度器地址：**
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https://kubernetes.io/docs/concepts/scheduling/kube-scheduler/
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---
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vssueId: 170
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# layout: StepLayout
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sharingTitle: CKA备考打卡 - 每日一题 - Day 5
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description: CKA备考打卡 - 每日一题 - Day 5
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meta:
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- name: keywords
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content: Kubernetes,K8S,CKA,Certified Kubernetes Administrator
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---
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# CKA每日一题 --- Day 5
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<AdSenseTitle/>
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::: tip 考题
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通过命令行，创建两个deployment。
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- 需要集群中有2个节点 ；
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- 第1个deployment名称为cka-1122-01，使用nginx镜像，有2个pod，并配置该deployment自身的pod之间在节点级别反亲和；
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- 第2个deployment名称为cka-1122-02，使用nginx镜像，有2个pod，并配置该deployment的pod与第1个deployment的pod在节点级别亲和；
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**最好提交最精简的deployment yaml，如果评论被限制，请提交反亲和性配置块yaml，也可多次评论提交**
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:::
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<b-button v-b-toggle.collapse-join-error variant="danger" size="sm" style="margin-top: 1rem;" v-on:click="$sendGaEvent('cka-daily', 'cka-daily', 'CKA每日一题003')">答案及解析</b-button>
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<b-collapse id="collapse-join-error" class="mt-2">
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<b-card style="background-color: rgb(254, 240, 240); border: solid 1px #F56C6C;">
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### 答案
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第一个deployment：cka-1122-01
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```yaml
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apiVersion: apps/v1
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kind: Deployment
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metadata:
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labels:
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app: cka-1122-01
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name: cka-1122-01
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spec:
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replicas: 2
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selector:
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matchLabels:
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app: cka-1122-01
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template:
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metadata:
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labels:
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app: cka-1122-01
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spec:
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containers:
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- image: nginx
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name: cka-1122-01
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affinity:
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podAntiAffinity:
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requiredDuringSchedulingIgnoredDuringExecution:
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labelSelector:
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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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- cka-1122-01
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topologyKey: "kubernetes.io/hostname"
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```
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## 第二个deployment：cka-1122-02
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```yaml
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apiVersion: apps/v1
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kind: Deployment
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metadata:
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labels:
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app: cka-1122-02
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name: cka-1122-02
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spec:
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replicas: 2
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selector:
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matchLabels:
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app: cka-1122-02
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template:
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metadata:
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labels:
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app: cka-1122-02
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spec:
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containers:
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- image: nginx
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name: cka-1122-02
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affinity:
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podAffinity:
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requiredDuringSchedulingIgnoredDuringExecution:
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- labelSelector:
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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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- cka-1122-01
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topologyKey: "kubernetes.io/hostname"
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```
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最终调度结果：
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``` sh
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NAME READY STATUS RESTARTS AGE IP NODE
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cka-1122-01-5df9bdf8c9-qwd2v 1/1 Running 0 8m 10.192.4.2 node-1
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cka-1122-01-5df9bdf8c9-r4rhs 1/1 Running 0 8m 10.192.4.3 node-2
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cka-1122-02-749cd4b846-bjhzq 1/1 Running 0 10m 10.192.4.4 node-1
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cka-1122-02-749cd4b846-rkgpo 1/1 Running 0 10m 10.192.4.5 node-2
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```
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### 解析
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**考点：k8s中的高级调度及用法。**
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亲和性和反亲和性调度官方文档：
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[https://kubernetes.io/docs/concepts/configuration/assign-pod-node/](https://kubernetes.io/docs/concepts/configuration/assign-pod-node/)
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中文文档： [https://kuboard.cn/learning/k8s-intermediate/config/assign-pod-node.html](https://kuboard.cn/learning/k8s-intermediate/config/assign-pod-node.html)
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#### 将 Pod 调度到特定的 Node 上：nodeSelector
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nodeSelector是节点选择约束的最简单推荐形式。nodeSelector是PodSpec下的一个字段。它指定键值对的映射。为了使Pod可以在节点上运行，该节点必须具有每个指定的键值对作为label。
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> 语法格式：map[string]string
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>
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> 作用：
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> – 匹配node.labels
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> – 排除不包含nodeSelector中指定label的所有node
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> – 匹配机制 —— 完全匹配
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#### nodeSelector 升级版：nodeAffinity
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节点亲和性在概念上类似于nodeSelector，它可以根据节点上的标签来限制Pod可以被调度在哪些节点上。
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**红色框为硬性过滤：**排除不具备指定label的node；在预选阶段起作用；
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**绿色框为软性评分：**不具备指定label的node打低分， 降低node被选中的几率；在优选阶段起作用；
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#### 与nodeSelector关键差异
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> – 引入运算符：In，NotIn （labelselector语法） – 支持枚举label可能的取值，如 zone in [az1, az2, az3...] – 支持硬性过滤和软性评分
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>
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> – 硬性过滤规则支持指定多条件之间的逻辑或运算 – 软性评分规则支持 设置条件权重值
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#### 让某些 Pod 分布在同一组 Node 上：podAffinity
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Pod亲和性和反亲和性可以基于已经在节点上运行的Pod上的标签而不是基于节点上的标签，来限制Pod调度的节点。
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**规则的格式为：**
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如果该X已经在运行一个或多个满足规则Y的Pod，则该Pod应该（或者在反亲和性的情况下不应该）在X中运行。
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Y表示为LabelSelector。X是一个拓扑域，例如节点，机架，云提供者区域，云提供者区域等。
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红框硬性过滤：排除不具备指定pod的node组；在预选阶段起作用；绿框软性评分：不具备指定pod的node组打低分， 降低该组node被选中的几率；在优选阶段起作用；
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#### 与nodeAffinity的关键差异
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> – 定义在PodSpec中，亲和与反亲和规则具有对称性 – labelSelector的匹配对象为Pod – 对node分组，依据label-key=topologyKey，每个labelvalue取值为一组
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>
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> – 硬性过滤规则，条件间只有逻辑与运算
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#### 避免某些 Pod 分布在同一组 Node 上：podAntiAffinity
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#### 与podAffinity的差异
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> – 匹配过程相同
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>
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> – 最终处理调度结果时取反
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> 即
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> – podAffinity中可调度节点，在podAntiAffinity中为不可调度
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> – podAffinity中高分节点，在podAntiAffinity中为低分
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</b-card>
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</b-collapse>
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> CKA 考试每日一题系列，全部内容由 [我的小碗汤](https://mp.weixin.qq.com/s/5tYgb_eSzHz_TMsi0U32gw) 创作，本站仅做转载
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<JoinCKACommunity/>
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