一、环境准备
我们紧接上一节的环境，进行下面的操作，如果不清楚的，可以先查看上一篇博文。
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。
二、更新
我们查看一下上一节的配置文件mytest-deploy.yaml。
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: mytest
spec:
replicas: 3
template:
metadata:
labels:
run: mytest
spec:
containers:
- name: mytest
image: wangzan18/mytest:v1
ports:
- containerPort: 80我们看到设定的镜像版本为v1，我们查看一下创建的ReplicaSet。
[[email protected] ~]# kubectl get rs -o wide
NAME DESIRED CURRENT READY AGE CONTAINERS IMAGES SELECTOR
mytest-88d46bf99 3 3 3 68m mytest wangzan18/mytest:v1 pod-template-hash=88d46bf99,run=mytest目前运行的 Pod 由 ReplicaSet mytest-88d46bf99进行控制，我们将配置文件中的 v1 替换为 v2，再次应用。
[[email protected] ~]# kubectl apply -f mytest-deploy.yaml
deployment.extensions/mytest configured
[[email protected] ~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
mytest-56c55b4c6-6gjxc 1/1 Running 0 24s
mytest-56c55b4c6-f5trx 1/1 Running 0 18s
mytest-56c55b4c6-sh5wd 1/1 Running 0 24s
mytest-88d46bf99-48f6n 1/1 Terminating 0 70m
mytest-88d46bf99-mv6cf 1/1 Terminating 0 70m
mytest-88d46bf99-p9w79 1/1 Terminating 0 70m[[email protected] ~]# kubectl get deploy -o wide
NAME READY UP-TO-DATE AVAILABLE AGE CONTAINERS IMAGES SELECTOR
mytest 3/3 3 3 72m mytest wangzan18/mytest:v2 run=mytest
[[email protected] ~]# kubectl get rs -o wide
NAME DESIRED CURRENT READY AGE CONTAINERS IMAGES SELECTOR
mytest-56c55b4c6 3 3 3 59s mytest wangzan18/mytest:v2 pod-template-hash=56c55b4c6,run=mytest
mytest-88d46bf99 0 0 0 71m mytest wangzan18/mytest:v1 pod-template-hash=88d46bf99,run=mytest我们可以看到 Deployment 的镜像更新为wangzan18/mytest:v2，创建了新的 ReplicaSet mytest-56c55b4c6，并管理了三个新的 Pod。
[[email protected] ~]# kubectl describe deployment mytest
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal ScalingReplicaSet 4m9s deployment-controller Scaled up replica set mytest-56c55b4c6 to 1
Normal ScalingReplicaSet 4m9s deployment-controller Scaled down replica set mytest-88d46bf99 to 2
Normal ScalingReplicaSet 4m9s deployment-controller Scaled up replica set mytest-56c55b4c6 to 2
Normal ScalingReplicaSet 4m3s deployment-controller Scaled down replica set mytest-88d46bf99 to 1
Normal ScalingReplicaSet 4m3s deployment-controller Scaled up replica set mytest-56c55b4c6 to 3
Normal ScalingReplicaSet 4m3s deployment-controller Scaled down replica set mytest-88d46bf99 to 0每次只更新替换一个 Pod。
三、回滚
kubectl apply 每次更新应用时 Kubernetes 都会记录下当前的配置，保存为一个 revision（版次），这样就可以回滚到某个特定 revision。
默认配置下，Kubernetes 只会保留最近的几个 revision，可以在 Deployment 配置文件中通过 revisionHistoryLimit 属性增加 revision 数量。
通过命令kubectl rollout undo我们可以回滚到上一个版本。
[[email protected] ~]# kubectl rollout undo deploy mytest
deployment.extensions/mytest rolled back[[email protected] ~]# kubectl get rs -o wide
NAME DESIRED CURRENT READY AGE CONTAINERS IMAGES SELECTOR
mytest-56c55b4c6 0 0 0 12m mytest wangzan18/mytest:v2 pod-template-hash=56c55b4c6,run=mytest
mytest-88d46bf99 3 3 3 82m mytest wangzan18/mytest:v1 pod-template-hash=88d46bf99,run=mytest可以看到三个 Pod 重新由镜像为wangzan18/mytest:v1的ReplicaSet进行接管。
原文地址：http://blog.51cto.com/wzlinux/2328833
时间： 2024-10-06 22:57:27