CKA 006、CICD
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huanqing.shao
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<b-button v-b-toggle.collapse-join-error variant="danger" size="sm" style="margin-top: 1rem;" v-on:click="$sendGaEvent('cka-daily', 'cka-daily', 'CKA每日一题003')">答案及解析</b-button>
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<b-button v-b-toggle.collapse-join-error variant="danger" size="sm" style="margin-top: 1rem;" v-on:click="$sendGaEvent('cka-daily', 'cka-daily', 'CKA每日一题004')">答案及解析</b-button>
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<b-button v-b-toggle.collapse-join-error variant="danger" size="sm" style="margin-top: 1rem;" v-on:click="$sendGaEvent('cka-daily', 'cka-daily', 'CKA每日一题003')">答案及解析</b-button>
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<b-button v-b-toggle.collapse-join-error variant="danger" size="sm" style="margin-top: 1rem;" v-on:click="$sendGaEvent('cka-daily', 'cka-daily', 'CKA每日一题005')">答案及解析</b-button>
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t/cka/daily/006.md
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t/cka/daily/006.md
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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 6
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description: CKA备考打卡 - 每日一题 - Day 6
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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 6
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<AdSenseTitle/>
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::: tip 考题
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通过命令行，创建1个deployment，副本数为3，镜像为 `nginx:latest`。然后滚动升 级到 `nginx:1.9.1`，再回滚到原来的版本
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要求：Deployment的名称为cka-1125，贴出用到的相关命令。
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最好附带创建的Deployment完整yaml，以及和升级回滚有关的命令。
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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006')">答案及解析</b-button>
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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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先创建deployment，可以用命令创建：
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```
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kubectl run cka-1125 --image=nginx --replicas=3
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```
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也可以用以下yaml：cka-1125.yaml创建
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```
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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-1125
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name: cka-1125
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spec:
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replicas: 3
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selector:
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matchLabels:
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app: cka-1125
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template:
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metadata:
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labels:
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app: cka-1125
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spec:
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containers:
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- image: nginx
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name: cka-1125
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```
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创建：
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```
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kubectl apply -f cka-1125.yaml
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```
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升级：
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```
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kubectl set image deploy/cka-1125 cka-1125=nginx:1.9.1 --record
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deployment.extensions/cka-1125 image updated
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```
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回滚：
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```
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# 回滚到上一个版本
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kubectl rollout undo deploy/cka-1125
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# 回滚到指定版本
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kubectl rollout undo deploy/cka-1125 --to-revision=2
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```
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## 解析
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**官方中set image命令：**
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[https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#set](https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#set)
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### set image命令
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set image命令格式如下：
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```
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kubectl set image (-f FILENAME | TYPE NAME) CONTAINER_NAME_1=CONTAINER_IMAGE_1 ... CONTAINER_NAME_N=CONTAINER_IMAGE_N [--record]
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```
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--record指定，在annotation中记录当前的kubectl命令。如果设置为false，则不记录命令。如果设置为true，则记录命令。默认为false。
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```
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[root@liabio test]# kubectl set image deploy/cka-1125 cka-1125=nginx:1.9.1 --record
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deployment.extensions/cka-1125 image updated
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[root@liabio test]#
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[root@liabio test]# kubectl rollout history deploy/cka-1125
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deployment.extensions/cka-1125
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REVISION CHANGE-CAUSE
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3 <none>
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4 kubectl set image deploy/cka-1125 cka-1125=nginx:1.9.1 --record=true
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```
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像上面这样，CHANGE-CAUSE中会有升级命令。
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`set image`命令可以对：`pod (po), replicationcontroller (rc), deployment (deploy), daemonset (ds), replicaset (rs)，statefulset(sts)`进行操作。
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### roll命令
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**roll命令官方文档：**
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[https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#rollout](https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#rollout)
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可以管理`deployments、daemonsets、statefulsets`资源的回滚：
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查询升级历史：
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```
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[root@liabio test]# kubectl rollout history deploy/cka-1125
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deployment.extensions/cka-1125
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REVISION CHANGE-CAUSE
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1 <none>
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2 <none>
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```
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查看指定版本的详细信息：
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```
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kubectl rollout history deploy/cka-1125 --revision=3 -o=yaml
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```
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回滚到上一个版本：
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```
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[root@liabio test]# kubectl rollout undo deploy/cka-1125
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deployment.extensions/cka-1125 rolled back
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```
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或者回滚到指定版本：
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```
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[root@liabio test]# kubectl rollout undo deploy/cka-1125 --to-revision=3
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deployment.extensions/cka-1125 rolled back
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```
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### 其他roll子命令
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restart：资源将重新启动；
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status：展示回滚状态；
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resume：恢复被暂停的资源。控制器不会控制被暂停的资源。通过恢复资源，可以让控制器再次控制。resume仅对deployment支持。
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pause：控制器不会控制被暂停的资源。使用`kubectl rollout resume`来恢复暂停的资源。当前，只有deployment支持被暂停。
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### 滚动更新策略
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**滚动更新官网文档：**
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[https://kubernetes.io/docs/concepts/workloads/controllers/deployment/](https://kubernetes.io/docs/concepts/workloads/controllers/deployment/)
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中文文档： [滚动更新](/learning/k8s-intermediate/workload/wl-deployment/update.html)
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```
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minReadySeconds: 5
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strategy:
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type: RollingUpdate
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rollingUpdate:
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maxSurge: 1
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maxUnavailable: 1
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```
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**minReadySeconds**
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Kubernetes在等待设置的时间后才进行升级
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如果没有设置该值，Kubernetes会假设该容器启动起来后就提供服务了
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如果没有设置该值，在某些极端情况下可能会造成服务服务正常运行
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**maxSurge**
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控制滚动更新过程中副本总数超过DESIRED的上限。maxSurge可以是具体的整数，也可以是百分比，向上取整。maxSurge默认值为25%。
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例如DESIRED为10，那么副本总数的最大值为roundUp(10 + 10*25%)=13,所以CURRENT为13。
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**maxUnavaible**
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控制滚动更新过程中，不可用副本占DESIRED的最大比例。maxUnavailable可以是具体的整数，也可以是百分之百，向下取整。默认值为25%。
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例如DESIRED为10，那么可用的副本数至少要为 `10-roundDown(10*25%)=8`所以AVAILABLE为8。
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**maxSurge越大，初始创建的新副本数量就越多；maxUnavailable越大，初始销毁的旧副本数目就越多。**
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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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