kubernetes rolling update
-
- Rolling update
- 1. Create Deployment
- 2. Update image
- 3. Observation
- 4. Rollback
- 参考链接：
- Rolling update
Rolling update
1. Create Deployment
# kubectl apply -f wether.cm.yaml
# kubectl apply -f weather-jmx.deploy.yaml --record产生了新的rs 。
[root@k8s-master ~]# kubectl get rs -w | egrep "jmx|NAME"
NAME DESIRED CURRENT READY AGE
weather-jmx-1809594718 3 3 3 35s2. Update image
模拟版本升级，更换deployment 中使用的镜像。
这里以直接修改yaml文件为例：
用文本编辑器打开weather-jmx.deploy.yaml， 将镜像改为：
172.16.18.5:30088/admin/centos7.1-v1-wth:test
执行：
[root@k8s-master ~]# kubectl replace -f weather-jmx.deploy.yaml --record
deployment "weather-jmx" replaced3. Observation
[root@k8s-master ~]# kubectl get rs -w | egrep "jmx"
weather-jmx-1809594718 3 3 3 52s
weather-jmx-790510206 1 0 0 0s
weather-jmx-1809594718 2 3 3 9m
weather-jmx-790510206 1 0 0 0s
weather-jmx-790510206 1 1 0 0s
weather-jmx-1809594718 2 3 3 9m
weather-jmx-1809594718 2 2 2 9m
weather-jmx-790510206 2 1 0 0s
weather-jmx-790510206 2 1 0 0s
weather-jmx-790510206 2 2 0 0s
weather-jmx-790510206 2 2 1 4s
weather-jmx-1809594718 1 2 2 9m
weather-jmx-1809594718 1 2 2 9m
weather-jmx-790510206 3 2 1 4s
weather-jmx-1809594718 1 1 1 9m
weather-jmx-790510206 3 2 1 4s
weather-jmx-790510206 3 3 1 4s
weather-jmx-790510206 3 3 2 6s
weather-jmx-1809594718 0 1 1 9m
weather-jmx-1809594718 0 1 1 9m
weather-jmx-1809594718 0 0 0 9m
weather-jmx-790510206 3 3 3 7s通过 kubectl get rs -w 命令可以观察到,更新镜像后创建了一个新的rs.
从上图可以看出，新的rs 从1开始，逐渐的替换掉来原来的3个pod. 而原来的rs也由3个pod，逐渐变为0个pod. 由此完成了整个滚动升级的过程。
升级完成
可以通过 rollout history 来查看Deployment的滚动日志。
[root@k8s-master ~]# kubectl rollout history deployment/weather-jmx
deployments "weather-jmx"
REVISION CHANGE-CAUSE
1 kubectl apply -f weather-jmx.deploy.yaml --record
2 kubectl replace -f weather-jmx.deploy.yaml --record4. Rollback
如果需要回退到上个版本，执行：
[root@k8s-master ~]# kubectl rollout undo deployment/weather-jmx
deployment "weather-jmx" rolled back回退过程同滚动升级过程一致：
[root@k8s-master ~]# kubectl get rs -w | egrep "jmx"
weather-jmx-1809594718 0 0 0 13m
weather-jmx-790510206 3 3 3 3m
weather-jmx-1809594718 0 0 0 13m
weather-jmx-1809594718 1 0 0 13m
weather-jmx-790510206 2 3 3 4m
weather-jmx-1809594718 1 0 0 13m
weather-jmx-1809594718 1 1 0 13m
weather-jmx-790510206 2 3 3 4m
weather-jmx-790510206 2 2 2 4m
weather-jmx-1809594718 2 1 0 13m
weather-jmx-1809594718 2 1 0 13m
weather-jmx-1809594718 2 2 0 13m
weather-jmx-1809594718 2 2 1 13m
weather-jmx-790510206 1 2 2 4m
weather-jmx-790510206 1 2 2 4m
weather-jmx-1809594718 3 2 1 13m
weather-jmx-790510206 1 1 1 4m
weather-jmx-1809594718 3 2 1 13m
weather-jmx-1809594718 3 3 1 13m
weather-jmx-1809594718 3 3 2 13m
weather-jmx-790510206 0 1 1 4m
weather-jmx-790510206 0 1 1 4m
weather-jmx-790510206 0 0 0 4m
weather-jmx-1809594718 3 3 3 13m[root@k8s-master ~]# kubectl rollout history deployment/weather-jmx
deployments "weather-jmx"
REVISION CHANGE-CAUSE
2 kubectl replace -f weather-jmx.deploy.yaml --record
3 kubectl apply -f weather-jmx.deploy.yaml --record通过 rollout history 可以发现，当前的revision 为3。也可以通过
# kubectl rollout undo deployment/weather-jmx --revision=来回退到具体某个版本
参考链接：
https://kubernetes.io/docs/concepts/workloads/controllers/deployment/
https://tachingchen.com/tw/blog/Kubernetes-Rolling-Update-with-Deployment/