227 lines
11 KiB
Markdown
227 lines
11 KiB
Markdown
---
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vssueId: 36
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layout: LearningLayout
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description: 本文描述了如何在 Kubernetes 中回滚 Deployment
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---
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# 回滚 Deployment
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[返回 Deployment](./#deployment-概述)
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某些情况下，您可能想要回滚（rollback）Deployment，例如：Deployment 不稳定（可能是不断地崩溃）。默认情况下，kubernetes 将保存 Deployment 的所有更新（rollout）历史。您可以设定 revision history limit 来确定保存的历史版本数量。
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::: tip
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当且仅当 Deployment 的 `.spec.template` 字段被修改时（例如，您修改了容器的镜像），kubernetes 将为其创建一个 Deployment revision（版本）。Deployment 的其他更新（例如：修改 `.spec.replicas` 字段）将不会创建新的 Deployment reviesion（版本）。
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:::
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<el-tabs type="border-card">
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<el-tab-pane label="使用 kubectl 回滚 Deployment">
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<h2>模拟更新错误</h2>
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* 假设您在更新 Deployment 的时候，犯了一个拼写错误，将 `nginx:1.9.1` 写成了 `nginx:1.91`
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``` sh
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kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:1.91 --record=true
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```
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输出结果如下所示：
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```
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deployment.apps/nginx-deployment image updated
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```
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* 该更新将卡住，您可以执行命令 `kubectl rollout status deployment.v1.apps/nginx-deployment` 检查其状态，输出结果如下所示：
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```
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Waiting for rollout to finish: 1 out of 3 new replicas have been updated...
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```
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* 执行命令 `kubectl get rs` 您将看到两个旧的 ReplicaSet（nginx-deployment-1564180365 and nginx-deployment-2035384211）和一个新的 ReplicaSet (nginx-deployment-3066724191) 。如下所示：
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```
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NAME DESIRED CURRENT READY AGE
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nginx-deployment-1564180365 3 3 3 25s
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nginx-deployment-2035384211 0 0 0 36s
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nginx-deployment-3066724191 1 1 0 6s
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```
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* 执行命令 `kubectl get pods`，您将看到 1 个由新 ReplicaSet 创建的 Pod 卡在抓取 image 的死循环里：
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```
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NAME READY STATUS RESTARTS AGE
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nginx-deployment-1564180365-70iae 1/1 Running 0 25s
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nginx-deployment-1564180365-jbqqo 1/1 Running 0 25s
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nginx-deployment-1564180365-hysrc 1/1 Running 0 25s
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nginx-deployment-3066724191-08mng 0/1 ImagePullBackOff 0 6s
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```
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::: tip
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Deployment Controller 将自动停止有问题的更新（rollout），不会继续 scale up 新的 ReplicaSet。maxUnavailable 参数指定了最多会有几个 Pod 副本卡住，该参数的默认值是 25%。
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:::
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* 执行命令 `kubectl describe deployment` 查看 Deployment 的详情，输出结果如下所示：
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```
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Name: nginx-deployment
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Namespace: default
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CreationTimestamp: Tue, 15 Mar 2016 14:48:04 -0700
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Labels: app=nginx
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Selector: app=nginx
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Replicas: 3 desired | 1 updated | 4 total | 3 available | 1 unavailable
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StrategyType: RollingUpdate
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MinReadySeconds: 0
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RollingUpdateStrategy: 25% max unavailable, 25% max surge
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Pod Template:
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Labels: app=nginx
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Containers:
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nginx:
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Image: nginx:1.91
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Port: 80/TCP
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Host Port: 0/TCP
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Environment: <none>
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Mounts: <none>
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Volumes: <none>
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Conditions:
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Type Status Reason
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---- ------ ------
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Available True MinimumReplicasAvailable
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Progressing True ReplicaSetUpdated
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OldReplicaSets: nginx-deployment-1564180365 (3/3 replicas created)
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NewReplicaSet: nginx-deployment-3066724191 (1/1 replicas created)
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Events:
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FirstSeen LastSeen Count From SubobjectPath Type Reason Message
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--------- -------- ----- ---- ------------- -------- ------ -------
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1m 1m 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set nginx-deployment-2035384211 to 3
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22s 22s 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set nginx-deployment-1564180365 to 1
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22s 22s 1 {deployment-controller } Normal ScalingReplicaSet Scaled down replica set nginx-deployment-2035384211 to 2
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22s 22s 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set nginx-deployment-1564180365 to 2
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21s 21s 1 {deployment-controller } Normal ScalingReplicaSet Scaled down replica set nginx-deployment-2035384211 to 1
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21s 21s 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set nginx-deployment-1564180365 to 3
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13s 13s 1 {deployment-controller } Normal ScalingReplicaSet Scaled down replica set nginx-deployment-2035384211 to 0
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13s 13s 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set nginx-deployment-3066724191 to 1
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```
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为了修复这个问题，您需要将其回滚到之前的一个稳定版本。
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<h2>检查 Deployment 的更新历史</h2>
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1. 执行命令 `kubectl rollout history deployment.v1.apps/nginx-deployment` 检查 Deployment 的历史版本，输出结果如下所示：
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```
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deployments "nginx-deployment"
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REVISION CHANGE-CAUSE
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1 kubectl apply --filename=https://k8s.io/examples/controllers/nginx-deployment.yaml --record=true
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2 kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:1.9.1 --record=true
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3 kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:1.91 --record=true
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```
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**CHANGE-CAUSE** 是该 revision（版本）创建时从 Deployment 的 annotation `kubernetes.io/change-cause` 拷贝而来。
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您可以通过如下方式制定 **CHANGE-CAUSE** 信息：
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* 为 Deployment 增加注解，`kubectl annotate deployment.v1.apps/nginx-deployment kubernetes.io/change-cause="image updated to 1.9.1"`
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* 执行 kubectl apply 命令时，增加 `--record` 选项
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* 手动编辑 Deployment 的 `.metadata.annotation` 信息
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2. 执行命令 `kubectl rollout history deployment.v1.apps/nginx-deployment --revision=2`，查看 revision（版本）的详细信息，输出结果如下所示：
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```
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deployments "nginx-deployment" revision 2
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Labels: app=nginx
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pod-template-hash=1159050644
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Annotations: kubernetes.io/change-cause=kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:1.9.1 --record=true
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Containers:
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nginx:
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Image: nginx:1.9.1
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Port: 80/TCP
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QoS Tier:
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cpu: BestEffort
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memory: BestEffort
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Environment Variables: <none>
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No volumes.
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```
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<h2>回滚到前一个 revision（版本）</h2>
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下面的步骤可将 Deployment 从当前版本回滚到前一个版本（version 2）
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1. 执行命令 `kubectl rollout undo deployment.v1.apps/nginx-deployment` 将当前版本回滚到前一个版本，输出结果如下所示：
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```
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deployment.apps/nginx-deployment
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```
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或者，您也可以使用 `--to-revision` 选项回滚到前面的某一个指定版本，执行如下命令：
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```sh
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kubectl rollout undo deployment.v1.apps/nginx-deployment --to-revision=2
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```
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输出结果如下：
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```
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deployment.apps/nginx-deployment
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```
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更详细的信息，请参考 [kubectl rollout](https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#rollout)
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此时，Deployment 已经被回滚到前一个稳定版本。您可以看到 Deployment Controller 为该 Deployment 产生了 DeploymentRollback event。
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2. 执行命令 `kubectl get deployment nginx-deployment`，检查该回滚是否成功，Deployment 是否按预期的运行，输出结果如下：
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```
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NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
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nginx-deployment 3 3 3 3 30m
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```
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3. 执行命令 `kubectl describe deployment nginx-deployment` 查看 Deployment 的详情，输出结果如下：
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```
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Name: nginx-deployment
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Namespace: default
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CreationTimestamp: Sun, 02 Sep 2018 18:17:55 -0500
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Labels: app=nginx
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Annotations: deployment.kubernetes.io/revision=4
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kubernetes.io/change-cause=kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:1.9.1 --record=true
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Selector: app=nginx
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Replicas: 3 desired | 3 updated | 3 total | 3 available | 0 unavailable
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StrategyType: RollingUpdate
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MinReadySeconds: 0
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RollingUpdateStrategy: 25% max unavailable, 25% max surge
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Pod Template:
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Labels: app=nginx
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Containers:
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nginx:
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Image: nginx:1.9.1
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Port: 80/TCP
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Host Port: 0/TCP
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Environment: <none>
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Mounts: <none>
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Volumes: <none>
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Conditions:
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Type Status Reason
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---- ------ ------
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Available True MinimumReplicasAvailable
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Progressing True NewReplicaSetAvailable
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OldReplicaSets: <none>
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NewReplicaSet: nginx-deployment-c4747d96c (3/3 replicas created)
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Events:
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Type Reason Age From Message
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---- ------ ---- ---- -------
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Normal ScalingReplicaSet 12m deployment-controller Scaled up replica set nginx-deployment-75675f5897 to 3
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Normal ScalingReplicaSet 11m deployment-controller Scaled up replica set nginx-deployment-c4747d96c to 1
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Normal ScalingReplicaSet 11m deployment-controller Scaled down replica set nginx-deployment-75675f5897 to 2
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Normal ScalingReplicaSet 11m deployment-controller Scaled up replica set nginx-deployment-c4747d96c to 2
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Normal ScalingReplicaSet 11m deployment-controller Scaled down replica set nginx-deployment-75675f5897 to 1
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Normal ScalingReplicaSet 11m deployment-controller Scaled up replica set nginx-deployment-c4747d96c to 3
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Normal ScalingReplicaSet 11m deployment-controller Scaled down replica set nginx-deployment-75675f5897 to 0
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Normal ScalingReplicaSet 11m deployment-controller Scaled up replica set nginx-deployment-595696685f to 1
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Normal DeploymentRollback 15s deployment-controller Rolled back deployment "nginx-deployment" to revision 2
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Normal ScalingReplicaSet 15s deployment-controller Scaled down replica set nginx-deployment-595696685f to 0
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```
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</el-tab-pane>
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<el-tab-pane label="使用 Kuboard 回滚 Deployment">
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正在撰写中
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</el-tab-pane>
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</el-tabs>
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[返回 Deployment](./#deployment-概述)
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