Kubernetes----Deployment控制器实现版本回退

Kubernetes----Deployment控制器实现版本回退

一、版本升级过程的变化原理

编辑pc_deployment.yaml文件，内容如下：

apiVersion: v1kind: Namespacemetadata: name: dev---apiVersion: apps/v1kind: Deploymentmetadata: name: pc-deployment namespace: devspec: replicas: 3 strategy: type: RollingUpdate rollingUpdate: maxUnavailable: 25% maxSurge: 25% selector: matchLabels: app: nginx-pod template: metadata: labels: app: nginx-pod spec: containers: - name: nginx image: nginx:1.17.1

使用如下命令创建资源，注意加–record参数，用于记录创建记录信息

[root@master pod_controller]# kubectl apply -f pc_deployment.yaml --record=truenamespace/dev createddeployment.apps/pc-deployment created[root@master pod_controller]#

然后编辑yaml文件，将镜像版本升级到1.17.2，再次使用上述命令 然后编辑yaml文件，将镜像版本升级到1.17.3，再次使用上述命令 然后编辑yaml文件，将镜像版本升级到1.17.4，再次使用上述命令 此时，通过如下命令可以查看到，有四个ReplicaSet

[root@master pod_controller]# kubectl get rs -n devNAME DESIRED CURRENT READY AGEpc-deployment-5d9c9b97bb 0 0 0 4m9spc-deployment-6b575b9c45 3 3 3 47spc-deployment-76fd8c7f84 0 0 0 88spc-deployment-7c7477c7ff 0 0 0

而通过监控ReplicaSet的变化过程如下看可以发现，在每次镜像升级的过程中，其实本质是每次都创建一个新的ReplicaSet，然后依次在新的ReplicaSet上创建pod

[root@master ~]# kubectl get rs -n dev -wNAME DESIRED CURRENT READY AGEpc-deployment-5d9c9b97bb 3 3 3 2m7spc-deployment-7c7477c7ff 1 0 0 0spc-deployment-7c7477c7ff 1 0 0 0spc-deployment-7c7477c7ff 1 1 0 0spc-deployment-7c7477c7ff 1 1 1 1spc-deployment-5d9c9b97bb 2 3 3 2m12spc-deployment-5d9c9b97bb 2 3 3 2m12spc-deployment-7c7477c7ff 2 1 1 1spc-deployment-5d9c9b97bb 2 2 2 2m12spc-deployment-7c7477c7ff 2 1 1 1spc-deployment-7c7477c7ff 2 2 1 1spc-deployment-7c7477c7ff 2 2 2 2spc-deployment-5d9c9b97bb 1 2 2 2m13spc-deployment-5d9c9b97bb 1 2 2 2m13spc-deployment-7c7477c7ff 3 2 2 2spc-deployment-5d9c9b97bb 1 1 1 2m13spc-deployment-7c7477c7ff 3 2 2 2spc-deployment-7c7477c7ff 3 3 2 2spc-deployment-7c7477c7ff 3 3 3 24spc-deployment-5d9c9b97bb 0 1 1 2m35spc-deployment-5d9c9b97bb 0 1 1 2m35spc-deployment-5d9c9b97bb 0 0 0 2m35spc-deployment-76fd8c7f84 1 0 0 0spc-deployment-76fd8c7f84 1 0 0 0spc-deployment-76fd8c7f84 1 1 0 0spc-deployment-76fd8c7f84 1 1 1 1spc-deployment-7c7477c7ff 2 3 3 31spc-deployment-7c7477c7ff 2 3 3 31spc-deployment-76fd8c7f84 2 1 1 1spc-deployment-76fd8c7f84 2 1 1 1spc-deployment-7c7477c7ff 2 2 2 31spc-deployment-76fd8c7f84 2 2 1 1spc-deployment-76fd8c7f84 2 2 2 2spc-deployment-7c7477c7ff 1 2 2 32spc-deployment-7c7477c7ff 1 2 2 32spc-deployment-76fd8c7f84 3 2 2 2spc-deployment-7c7477c7ff 1 1 1 32spc-deployment-76fd8c7f84 3 2 2 2spc-deployment-76fd8c7f84 3 3 2 2spc-deployment-76fd8c7f84 3 3 3 3spc-deployment-7c7477c7ff 0 1 1 33spc-deployment-7c7477c7ff 0 1 1 33spc-deployment-7c7477c7ff 0 0 0 33spc-deployment-6b575b9c45 1 0 0 0spc-deployment-6b575b9c45 1 0 0 0spc-deployment-6b575b9c45 1 1 0 0spc-deployment-6b575b9c45 1 1 1 22spc-deployment-76fd8c7f84 2 3 3 63spc-deployment-6b575b9c45 2 1 1 22spc-deployment-76fd8c7f84 2 3 3 63spc-deployment-6b575b9c45 2 1 1 22spc-deployment-6b575b9c45 2 2 1 22spc-deployment-76fd8c7f84 2 2 2 63spc-deployment-6b575b9c45 2 2 2 45spc-deployment-76fd8c7f84 1 2 2 86spc-deployment-6b575b9c45 3 2 2 45spc-deployment-76fd8c7f84 1 2 2 86spc-deployment-76fd8c7f84 1 1 1 86spc-deployment-6b575b9c45 3 2 2 45spc-deployment-6b575b9c45 3 3 2 45spc-deployment-6b575b9c45 3 3 3 46spc-deployment-76fd8c7f84 0 1 1 87spc-deployment-76fd8c7f84 0 1 1 87spc-deployment-76fd8c7f84 0 0 0

二、版本回退

2.1 版本回退简介

deployment控制器支持版本回退，因为在每次升级的时候deployment都是创建了一个新的ReplicaSet，依次，版本回退就是回退到旧的ReplicaSet上即可

deployment版本回退相关的命令是：kubectl rollout 命令，后跟如下选项

status 显示当前升级状态history 显示升级历史记录pause 暂停版本升级过程resume 继续已经暂停的版本升级过程restart 重启版本升级过程undo 回滚到上一级版本（可以使用 --to-revision回滚到指定的版本）

2.2 版本回退

如下即查看当前升级状态

[root@master pod_controller]# kubectl rollout status deployment pc-deployment -n devdeployment "pc-deployment" successfully rolled out[root@master pod_controller]#

如下命令可以查看到升级历史记录

[root@master pod_controller]# kubectl rollout history deployment pc-deployment -n devdeployment.apps/pc-deploymentREVISION CHANGE-CAUSE1 kubectl apply --filename=pc_deployment.yaml --record=true2 kubectl apply --filename=pc_deployment.yaml --record=true3 kubectl apply --filename=pc_deployment.yaml --record=true4 kubectl apply --filename=pc_deployment.yaml --record=true[root@master pod_controller]#

通过如下命令即可回退到上个版本

[root@master pod_controller]# kubectl rollout undo deployment pc-deployment -n devdeployment.apps/pc-deployment rolled back[root@master pod_controller]#

此时查看历史版本如下，已经没有3了，而是多了一个5

[root@master pod_controller]# kubectl rollout history deployment pc-deployment -n devdeployment.apps/pc-deploymentREVISION CHANGE-CAUSE1 kubectl apply --filename=pc_deployment.yaml --record=true2 kubectl apply --filename=pc_deployment.yaml --record=true3 kubectl apply --filename=pc_deployment.yaml --record=true4 kubectl apply --filename=pc_deployment.yaml --record=true[root@master pod_controller]#

若直接回退到第一个版本，则使用如下命令即可

[root@master pod_controller]# kubectl rollout undo deployment pc-deployment --to-revision=1 -n devdeployment.apps/pc-deployment rolled back[root@master pod_controller]#

此时再次查看历史记录如下，此时1已经没有了，而多出来一个6

[root@master pod_controller]# kubectl rollout history deployment pc-deployment -n devdeployment.apps/pc-deploymentREVISION CHANGE-CAUSE2 kubectl apply --filename=pc_deployment.yaml --record=true4 kubectl apply --filename=pc_deployment.yaml --record=true5 kubectl apply --filename=pc_deployment.yaml --record=true6 kubectl apply --filename=pc_deployment.yaml --record=true[root@master pod_controller]#

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