9、Rolling Update滚动更新、回滚

Rolling Update

滚动更新是一次只更新一小部分副本，成功后，再更新更多的副本，最终完成所有副本的更新。滚动更新的最大的好处是零停机，整个更新过程始终有副本在运行，从而保证了业务的连续性。

 

run: httpd   和name: httpd 都可以

下面我们部署三副本应用，初始镜像为 httpd:2.2.31，然后将其更新到 httpd:2.2.32。

[root@master rolling]# vim httpd.yml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: httpd
spec:
  selector:
     matchLabels:
        run: httpd
  replicas: 3
  template:
    metadata:
      labels:
        run: httpd
    spec:
      containers:
      - name: httpd
        image: httpd:2.2.31

run: httpd   和name: httpd 都可以

通过 kubectl apply 部署。

[root@master rolling]# kubectl apply  -f httpd.yml 
deployment.apps/httpd created
[root@master rolling]# kubectl get deployment httpd -o wide
NAME    READY   UP-TO-DATE   AVAILABLE   AGE     CONTAINERS   IMAGES         SELECTOR
httpd   3/3     3            3           2m40s   httpd        httpd:2.2.31   run=httpd
[root@master rolling]# kubectl get replicaset -o wide 
NAME                            DESIRED   CURRENT   READY   AGE     CONTAINERS   IMAGES           SELECTOR
httpd-55f56846f                 3         3         3       3m21s   httpd        httpd:2.2.31     pod-template-hash=55f56846f,run=httpd
[root@master rolling]# kubectl get pod 
NAME                                  READY   STATUS    RESTARTS   AGE
httpd-55f56846f-7bthw                 1/1     Running   0          3m28s
httpd-55f56846f-7wzjs                 1/1     Running   0          3m28s
httpd-55f56846f-pjf5q                 1/1     Running   0          3m28s
[root@master rolling]# 

部署过程如下：
1、创建 Deployment httpd
2、创建 ReplicaSet h