Deployment 回滚

更新Deployment资源时，pod状态为Pending，使用delete命令是删不掉Pending的pod的，因为Deployment会无限创建，这时候需要用到Deployment的回滚功能

如下我更改了Deployment/Jenkins，但新创建的pod因为资源不足无法创建而处于pending状态：

$ kd get pod -n cicd
NAME                          READY   STATUS    RESTARTS   AGE
jenkins-5b688ddcc7-2zlwz      1/1     Running   0          5d23h
jenkins-8588ccc5c5-v4b2x      0/1     Pending   0          28s

如果删除pod，deployment就会重新创建pod，依然是pending状态

$ kubectl delete pod jenkins-8588ccc5c5-v4b2x -n cice
pod "jenkins-8588ccc5c5-v4b2x" deleted
$ kd get pod -n cicd
NAME                          READY   STATUS    RESTARTS   AGE
jenkins-5b688ddcc7-2zlwz      1/1     Running   0          5d23h
jenkins-8588ccc5c5-46qt2      0/1     Pending   0          5s

解决方法：

查看Deployment更新的历史版本，回滚到上一版本

# 查看历史版本
$ kubectl rollout history deployment jenkins -n cicd
deployment.apps/jenkins
REVISION  CHANGE-CAUSE
1         <none>
2         <none>

# 回滚到上一版本
$ kubectl rollout undo deployment/jenkins -n cicd
deployment.apps/jenkins rolled back

# 回滚成功，状态为pending的pod已被删除
$ kubectl get pod -n cicd
NAME                          READY   STATUS    RESTARTS   AGE
jenkins-5b688ddcc7-2zlwz      1/1     Running   0          5d23h