Kubernetes的RollingUpdate实战-创新互联

一.背景

随着Kubernetes的进一步深入使用，我们越来越体会到它给我们的工作带来的高效与便利。Rolling Update是Kubernetes系统中的一个强大的功能，能够为我们的运维工作带来极大的便利。

创新互联建站是网站建设专家,致力于互联网品牌建设与网络营销，专业领域包括成都网站制作、网站建设、电商网站制作开发、小程序制作、微信营销、系统平台开发，与其他网站设计及系统开发公司不同，我们的整合解决方案结合了恒基网络品牌建设经验和互联网整合营销的理念，并将策略和执行紧密结合，且不断评估并优化我们的方案，为客户提供全方位的互联网品牌整合方案！

二.步骤

2.1 部署最初始版本Deployment。

初始Deployment的YAML如下：

apiVersion: apps/v1beta1
kind: Deployment
metadata:
  name: deployment-rollout
spec:
  replicas: 4
  template:
    metadata:
      labels:
        test: httpd
    spec:
      containers:
      - name: httpd-rollout-test
        image: httpd:2.2.31
        ports:
        - containerPort: 80

执行命令：

[root@k8s-m ~]# kubectl get deployment -o wide
NAME                 DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE    CONTAINERS           IMAGES         SELECTOR
deployment-rollout   4         4         4            4           107s   httpd-rollout-test   httpd:2.2.31   test=httpd
[root@k8s-m ~]# kubectl get replicaset -o wide
NAME                            DESIRED   CURRENT   READY   AGE    CONTAINERS           IMAGES         SELECTOR
deployment-rollout-5fb9c69c5c   4         4         4       116s   httpd-rollout-test   httpd:2.2.31   pod-template-hash=5fb9c69c5c,test=httpd

2.2 将初始版本升级。

升级到2.4.31，YAML如下：

apiVersion: apps/v1beta1
kind: Deployment
metadata:
  name: deployment-rollout
spec:
  revisionHistoryLimit: 10
  replicas: 4
  template:
    metadata:
      labels:
        test: httpd
    spec:
      containers:
      - name: httpd-rollout-test
        image: httpd:2.4.33
        ports:
        - containerPort: 80

执行命令：

[root@k8s-m ~]# kubectl apply -f Httpd-Deployment-rollout-v1.yaml
deployment.apps/deployment-rollout configured
[root@k8s-m ~]# kubectl get deployment -o wide
NAME                 DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE     CONTAINERS           IMAGES         SELECTOR
deployment-rollout   4         5         2            3           3m57s   httpd-rollout-test   httpd:2.4.33   test=httpd
[root@k8s-m ~]# kubectl get replicaset -o wide
NAME                            DESIRED   CURRENT   READY   AGE     CONTAINERS           IMAGES         SELECTOR
deployment-rollout-54766f574f   2         2         0       93s     httpd-rollout-test   httpd:2.4.33   pod-template-hash=54766f574f,test=httpd
deployment-rollout-5fb9c69c5c   3         3         3       4m12s   httpd-rollout-test   httpd:2.2.31   pod-template-hash=5fb9c69c5c,test=httpd
[root@k8s-m ~]# kubectl get pod -o wide
NAME                                  READY   STATUS              RESTARTS   AGE     IP             NODE     NOMINATED NODE
deployment-rollout-54766f574f-668pc   0/1     ContainerCreating   0          114s             k8s-n1   
deployment-rollout-54766f574f-ssz67   0/1     ContainerCreating   0          115s             k8s-n2   
deployment-rollout-5fb9c69c5c-m5dvs   1/1     Running             0          4m34s   10.244.2.47    k8s-n2   
deployment-rollout-5fb9c69c5c-p9grr   1/1     Running             0          4m34s   10.244.1.113   k8s-n1   
deployment-rollout-5fb9c69c5c-tzm7w   1/1     Running             0          4m34s   10.244.2.48    k8s-n2

一会儿后再观察一下：

[root@k8s-m ~]# kubectl get replicaset -o wide
NAME                            DESIRED   CURRENT   READY   AGE     CONTAINERS           IMAGES         SELECTOR
deployment-rollout-54766f574f   4         4         4       4m24s   httpd-rollout-test   httpd:2.4.33   pod-template-hash=54766f574f,test=httpd
deployment-rollout-5fb9c69c5c   0         0         0       7m3s    httpd-rollout-test   httpd:2.2.31   pod-template-hash=5fb9c69c5c,test=httpd
[root@k8s-m ~]# kubectl get deployment -o wide
NAME                 DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE     CONTAINERS           IMAGES         SELECTOR
deployment-rollout   4         4         4            4           7m18s   httpd-rollout-test   httpd:2.4.33   test=httpd
[root@k8s-m ~]# kubectl get pod -o wide
NAME                                  READY   STATUS    RESTARTS   AGE     IP             NODE     NOMINATED NODE
deployment-rollout-54766f574f-668pc   1/1     Running   0          4m48s   10.244.1.114   k8s-n1   
deployment-rollout-54766f574f-h7gf9   1/1     Running   0          99s     10.244.2.50    k8s-n2   
deployment-rollout-54766f574f-ssz67   1/1     Running   0          4m49s   10.244.2.49    k8s-n2   
deployment-rollout-54766f574f-vklvr   1/1     Running   0          41s     10.244.1.115   k8s-n1

在此过程中，我们会发现，ReplicaSet deployment-rollout-5fb9c69c5c逐步被deployment-rollout-54766f574f取代，创建新版本的Pod之后，原始版本的Pod被终止。这是一个平滑的升级过程。Kubernetes提供了两个参数maxSurge和maxUnavailable来精细控制Pod的替换数量。

2.3 版本的回滚。

默认情况下，Kubernetes只会保留最近几个revision。在上面的升级过程中，通过revisionHistoryLimit设置了revision的数量。我们通过命令来看一下：

[root@k8s-m ~]# kubectl rollout history deployment deployment-rollout
deployment.extensions/deployment-rollout
REVISION  CHANGE-CAUSE
1         
2

继续升级。新版的YAML如下：

apiVersion: apps/v1beta1
kind: Deployment
metadata:
  name: deployment-rollout
spec:
  revisionHistoryLimit: 10
  replicas: 4
  template:
    metadata:
      labels:
        test: httpd
    spec:
      containers:
      - name: httpd-rollout-test
        image: httpd:2.4.34
        ports:
        - containerPort: 80

执行升级并记录升级日志。

[root@k8s-m ~]# kubectl apply -f Httpd-Deployment-rollout-v2.yaml --record
deployment.apps/deployment-rollout configured
[root@k8s-m ~]# kubectl rollout history deployment deployment-rollout
deployment.extensions/deployment-rollout
REVISION  CHANGE-CAUSE
1         
2         
3         kubectl apply --filename=Httpd-Deployment-rollout-v2.yaml --record=true
[root@k8s-m ~]# kubectl get deployment deployment-rollout -o wide
NAME                 DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS           IMAGES         SELECTOR
deployment-rollout   4         4         4            4           31m   httpd-rollout-test   httpd:2.4.34   test=httpd
[root@k8s-m ~]# kubectl get replicaset -o wide
NAME                            DESIRED   CURRENT   READY   AGE     CONTAINERS           IMAGES         SELECTOR
deployment-rollout-54766f574f   0         0         0       29m     httpd-rollout-test   httpd:2.4.33   pod-template-hash=54766f574f,test=httpd
deployment-rollout-54fc66bb6    4         4         4       6m12s   httpd-rollout-test   httpd:2.4.34   pod-template-hash=54fc66bb6,test=httpd
deployment-rollout-5fb9c69c5c   0         0         0       32m     httpd-rollout-test   httpd:2.2.31   pod-template-hash=5fb9c69c5c,test=httpd
[root@k8s-m ~]# kubectl get pod -o wide
NAME                                 READY   STATUS    RESTARTS   AGE     IP             NODE     NOMINATED NODE
deployment-rollout-54fc66bb6-2zvhk   1/1     Running   0          6m26s   10.244.1.116   k8s-n1   
deployment-rollout-54fc66bb6-7rsj6   1/1     Running   0          4m16s   10.244.1.117   k8s-n1   
deployment-rollout-54fc66bb6-nlx4h   1/1     Running   0          6m26s   10.244.2.51    k8s-n2   
deployment-rollout-54fc66bb6-xxnrg   1/1     Running   0          6m24s   10.244.2.52    k8s-n2

修改YAML文件中镜像的版本继续升级，观察升级结果：

[root@k8s-m ~]# kubectl rollout history deployment deployment-rollout
deployment.extensions/deployment-rollout
REVISION  CHANGE-CAUSE
1         
2         
3         kubectl apply --filename=Httpd-Deployment-rollout-v2.yaml --record=true
4         kubectl apply --filename=Httpd-Deployment-rollout-v3.yaml --record=true

[root@k8s-m ~]# kubectl get replicaset -o wide
NAME                            DESIRED   CURRENT   READY   AGE     CONTAINERS           IMAGES         SELECTOR
deployment-rollout-54766f574f   0         0         0       33m     httpd-rollout-test   httpd:2.4.33   pod-template-hash=54766f574f,test=httpd
deployment-rollout-54fc66bb6    0         0         0       10m     httpd-rollout-test   httpd:2.4.34   pod-template-hash=54fc66bb6,test=httpd
deployment-rollout-5b99bbfbbc   4         4         4       2m33s   httpd-rollout-test   httpd:2.4.35   pod-template-hash=5b99bbfbbc,test=httpd
deployment-rollout-5fb9c69c5c   0         0         0       36m     httpd-rollout-test   httpd:2.2.31   pod-template-hash=5fb9c69c5c,test=httpd
[root@k8s-m ~]# kubectl get pod -o wide
NAME                                  READY   STATUS    RESTARTS   AGE     IP             NODE     NOMINATED NODE
deployment-rollout-5b99bbfbbc-7mdg9   1/1     Running   0          65s     10.244.1.119   k8s-n1   
deployment-rollout-5b99bbfbbc-9mfbk   1/1     Running   0          2m40s   10.244.1.118   k8s-n1   
deployment-rollout-5b99bbfbbc-jn5sb   1/1     Running   0          2m40s   10.244.2.53    k8s-n2   
deployment-rollout-5b99bbfbbc-tr6t2   1/1     Running   0          2m38s   10.244.2.54    k8s-n2

httpd的image均已经升级到2.4.35，接下来我们试一下回滚到v2版本：

[root@k8s-m ~]# kubectl rollout undo deployment deployment-rollout --to-revision=3
deployment.extensions/deployment-rollout
[root@k8s-m ~]# kubectl get deployment -o wide
NAME                 DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS           IMAGES         SELECTOR
deployment-rollout   4         4         4            4           42m   httpd-rollout-test   httpd:2.4.34   test=httpd
[root@k8s-m ~]# kubectl get replicaset -o wide
NAME                            DESIRED   CURRENT   READY   AGE     CONTAINERS           IMAGES         SELECTOR
deployment-rollout-54766f574f   0         0         0       39m     httpd-rollout-test   httpd:2.4.33   pod-template-hash=54766f574f,test=httpd
deployment-rollout-54fc66bb6    4         4         4       16m     httpd-rollout-test   httpd:2.4.34   pod-template-hash=54fc66bb6,test=httpd
deployment-rollout-5b99bbfbbc   0         0         0       8m35s   httpd-rollout-test   httpd:2.4.35   pod-template-hash=5b99bbfbbc,test=httpd
deployment-rollout-5fb9c69c5c   0         0         0       42m     httpd-rollout-test   httpd:2.2.31   pod-template-hash=5fb9c69c5c,test=httpd
[root@k8s-m ~]# kubectl get pod -o wide
NAME                                 READY   STATUS    RESTARTS   AGE   IP             NODE     NOMINATED NODE
deployment-rollout-54fc66bb6-bjskn   1/1     Running   0          68s   10.244.1.121   k8s-n1   
deployment-rollout-54fc66bb6-c65th   1/1     Running   0          70s   10.244.2.55    k8s-n2   
deployment-rollout-54fc66bb6-cwpbk   1/1     Running   0          70s   10.244.1.120   k8s-n1   
deployment-rollout-54fc66bb6-lz9xt   1/1     Running   0          68s   10.244.2.56    k8s-n2   
[root@k8s-m ~]# kubectl rollout history deployment deployment-rollout
deployment.extensions/deployment-rollout
REVISION  CHANGE-CAUSE
1         
2         
4         kubectl apply --filename=Httpd-Deployment-rollout-v3.yaml --record=true
5         kubectl apply --filename=Httpd-Deployment-rollout-v2.yaml --record=true

每次升级或回滚操作之后REVISION的数字都会增加1。通过kubectl history，我们可以看到每次升级记录，--record记录了每次操作的详细过程。通过kubectl undo执行回滚操作，选项--to-revision指定了回滚的修订版本号。

三.总结

3.1. 再次被Kubernetes的魅力所折服，平常工作中的灰度升级/发布/更新（按批次停止老版本实例，启用新版本实例，新老版本共存，逐步扩大新版本范围，最终把所有用户迁移到新版本上），蓝绿升级/发布/更新（不停止老版本，另外部署一套新版本，新版本通过测试发布后删除老版本），滚动升级/发布/更新（一个或多个服务停止，执行更新，逐步将新版本投入使用，周而复始，最终完成整个集群中所有实例的版本更新）这些概念理解更加透彻。

3.2. 目前有些资料已经不适用于新版本了，不要被网上的资料所误导，一定要立足与官方文档和系统帮助。例如：

Kubernetes 的Deploy相关的命令只有:

Deploy Commands:
  rollout        Manage the rollout of a resource
  scale          为 Deployment, ReplicaSet, Replication Controller 或者 Job 设置一个新的副本数量
  autoscale      自动调整一个 Deployment, ReplicaSet, 或者 ReplicationController 的副本数量

Rollout可用资源类型：

Valid resource types include:
  * deployments
  * daemonsets
  * statefulsets

3.3 Rollout updat也可以通过YAML来实现，后续文章会介绍。

四.相关资料

4.1 本文相关的yaml文件

4.2 官方资料

另外有需要云服务器可以了解下创新互联cdcxhl.cn，海内外云服务器15元起步，三天无理由+7*72小时售后在线，公司持有idc许可证，提供“云服务器、裸金属服务器、高防服务器、香港服务器、美国服务器、虚拟主机、免备案服务器”等云主机租用服务以及企业上云的综合解决方案，具有“安全稳定、简单易用、服务可用性高、性价比高”等特点与优势，专为企业上云打造定制，能够满足用户丰富、多元化的应用场景需求。

网站标题：Kubernetes的RollingUpdate实战-创新互联
网站网址：http://dzwzjz.com/article/djiphi.html

大橙子网站建设，新征程启航