专栏首页踏歌行的专栏Kubernetes K8S之资源控制器RC、RS、Deployment详解

Kubernetes K8S之资源控制器RC、RS、Deployment详解

Kubernetes的资源控制器ReplicationController(RC)、ReplicaSet(RS)、Deployment(Deploy)详解与示例

主机配置规划

服务器名称(hostname)

系统版本

配置

内网IP

外网IP(模拟)

k8s-master

CentOS7.7

2C/4G/20G

172.16.1.110

10.0.0.110

k8s-node01

CentOS7.7

2C/4G/20G

172.16.1.111

10.0.0.111

k8s-node02

CentOS7.7

2C/4G/20G

172.16.1.112

10.0.0.112

什么是控制器

kubernetes中内建了很多controller(控制器),这些相当于一个状态机,用来控制pod的具体状态和行为。

部分控制器类型如下:

  • ReplicationController 和 ReplicaSet
  • Deployment
  • DaemonSet
  • StatefulSet
  • Job/CronJob
  • HorizontalPodAutoscaler

ReplicationController 和 ReplicaSet

ReplicationController (RC)用来确保容器应用的副本数始终保持在用户定义的副本数,即如果有容器异常退出,会自动创建新的pod来替代;而异常多出来的容器也会自动回收。

在新版的Kubernetes中建议使用ReplicaSet (RS)来取代ReplicationController。ReplicaSet跟ReplicationController没有本质的不同,只是名字不一样,但ReplicaSet支持集合式selector。

虽然 ReplicaSets 可以独立使用,但如今它主要被Deployments 用作协调 Pod 的创建、删除和更新的机制。当使用 Deployment 时,你不必担心还要管理它们创建的 ReplicaSet,Deployment 会拥有并管理它们的 ReplicaSet。

ReplicaSet 是下一代的 Replication Controller。 ReplicaSet 和 Replication Controller 的唯一区别是选择器的支持。ReplicaSet 支持新的基于集合的选择器需求,这在标签用户指南中有描述。而 Replication Controller 仅支持基于相等选择器的需求。

Deployments

Deployment 控制器为 Pods和 ReplicaSets提供描述性的更新方式。用来替代以前的ReplicationController以方便管理应用。

典型的应用场景包括:

  • 定义Deployment来创建Pod和ReplicaSet
  • 滚动升级和回滚应用
  • 扩容和缩容
  • 暂停和继续Deployment

ReplicaSet示例

yaml文件

 1 [root@k8s-master controller]# pwd
 2 /root/k8s_practice/controller
 3 [root@k8s-master controller]# cat ReplicaSet-01.yaml 
 4 apiVersion: apps/v1
 5 kind: ReplicaSet
 6 metadata:
 7   name: frontend
 8 spec:
 9   replicas: 3
10   selector:
11     matchLabels:
12       tier: frontend
13   template:
14     metadata:
15       labels:
16         tier: frontend
17     spec:
18       containers:
19       - name: nginx
20         image: registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17
21         imagePullPolicy: IfNotPresent
22         ports:
23         - name: httpd
24           containerPort: 80

创建ReplicaSet,并查看rs状态与详情

 1 [root@k8s-master controller]# kubectl apply -f ReplicaSet-01.yaml 
 2 replicaset.apps/frontend created
 3 [root@k8s-master controller]# kubectl get rs -o wide    # 查看状态
 4 NAME       DESIRED   CURRENT   READY   AGE     CONTAINERS   IMAGES                                                        SELECTOR
 5 frontend   3         3         3       2m12s   nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17   tier=frontend
 6 [root@k8s-master controller]# 
 7 [root@k8s-master controller]# kubectl describe rs frontend   # 查看详情
 8 Name:         frontend
 9 Namespace:    default
10 Selector:     tier=frontend
11 Labels:       <none>
12 Annotations:  kubectl.kubernetes.io/last-applied-configuration:
13                 {"apiVersion":"apps/v1","kind":"ReplicaSet","metadata":{"annotations":{},"name":"frontend","namespace":"default"},"spec":{"replicas":3,"se...
14 Replicas:     3 current / 3 desired
15 Pods Status:  3 Running / 0 Waiting / 0 Succeeded / 0 Failed
16 Pod Template:
17   Labels:  tier=frontend
18   Containers:
19    nginx:
20     Image:        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17
21     Port:         80/TCP
22     Host Port:    0/TCP
23     Environment:  <none>
24     Mounts:       <none>
25   Volumes:        <none>
26 Events:
27   Type    Reason            Age    From                   Message
28   ----    ------            ----   ----                   -------
29   Normal  SuccessfulCreate  10m    replicaset-controller  Created pod: frontend-kltwp
30   Normal  SuccessfulCreate  10m    replicaset-controller  Created pod: frontend-76dbn
31   Normal  SuccessfulCreate  10m    replicaset-controller  Created pod: frontend-jk8td

查看pod状态信息

1 [root@k8s-master controller]# kubectl get pod -o wide --show-labels
2 NAME             READY   STATUS    RESTARTS   AGE     IP            NODE         NOMINATED NODE   READINESS GATES   LABELS
3 frontend-76dbn   1/1     Running   0          5m15s   10.244.4.31   k8s-node01   <none>           <none>            tier=frontend
4 frontend-jk8td   1/1     Running   0          5m15s   10.244.2.35   k8s-node02   <none>           <none>            tier=frontend
5 frontend-kltwp   1/1     Running   0          5m15s   10.244.2.34   k8s-node02   <none>           <none>            tier=frontend

删除一个pod,然后再次查看

1 [root@k8s-master controller]# kubectl delete pod frontend-kltwp
2 pod "frontend-kltwp" deleted
3 [root@k8s-master controller]# 
4 [root@k8s-master controller]# kubectl get pod -o wide --show-labels   # 可见重新创建了一个pod
5 NAME             READY   STATUS    RESTARTS   AGE     IP            NODE         NOMINATED NODE   READINESS GATES   LABELS
6 frontend-76dbn   1/1     Running   0          7m27s   10.244.4.31   k8s-node01   <none>           <none>            tier=frontend
7 frontend-jk8td   1/1     Running   0          7m27s   10.244.2.35   k8s-node02   <none>           <none>            tier=frontend
8 frontend-mf79k   1/1     Running   0          16s     10.244.4.32   k8s-node01   <none>           <none>            tier=frontend

由上可见,rs又新建了一个pod,保证了pod数总是为3.

Deployment示例

创建 Deployment

yaml文件

 1 [root@k8s-master controller]# pwd
 2 /root/k8s_practice/controller
 3 [root@k8s-master controller]# cat nginx-deployment-1.17.1.yaml 
 4 apiVersion: apps/v1
 5 kind: Deployment
 6 metadata:
 7   name: nginx-deployment
 8   labels:
 9     app: nginx
10 spec:
11   replicas: 3
12   # 重点关注该字段
13   selector:
14     matchLabels:
15       app: nginx
16   template:
17     metadata:
18       labels:
19         app: nginx
20     spec:
21       containers:
22       - name: nginx
23         image: registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.1
24         ports:
25         - containerPort: 80
26 [root@k8s-master controller]# 
27 [root@k8s-master controller]# cat nginx-deployment-1.17.5.yaml 
28 apiVersion: apps/v1
29 kind: Deployment
30 metadata:
31   name: nginx-deployment
32   labels:
33     app: nginx
34 spec:
35   replicas: 3
36   # 重点关注该字段
37   selector:
38     matchLabels:
39       app: nginx
40   template:
41     metadata:
42       labels:
43         app: nginx
44     spec:
45       containers:
46       - name: nginx
47         image: registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.5
48         ports:
49         - containerPort: 80

selector 字段定义 Deployment 如何查找要管理的 Pods。 在这种情况下,会选择在 template(Pod)模板中定义的标签labels(app: nginx)。但更复杂的选择规则是可能的,只要 template (Pod) 模板本身满足规则。

刚启动时状态说明

启动deployment,并查看状态

1 [root@k8s-master controller]# kubectl apply -f nginx-deployment-1.17.1.yaml --record
2 deployment.apps/nginx-deployment created
3 [root@k8s-master controller]# 
4 [root@k8s-master controller]# kubectl get deployment -o wide
5 NAME               READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES                                                          SELECTOR
6 nginx-deployment   2/3     3            2           10s   nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.1   app=nginx
7 
8 # --record 参数可以记录命令,通过 kubectl rollout history deployment/nginx-deployment 可查询

参数说明:

  • NAME:列出集群中 Deployments 的名称
  • READY:已就绪副本数/期望副本数
  • UP-TO-DATE:显示已更新和正在更新中的副本数
  • AVAILABLE:显示应用程序可供用户使用的副本数
  • AGE:显示运行的时间

查看ReplicaSet状态

1 [root@k8s-master controller]# kubectl get rs -o wide
2 NAME                          DESIRED   CURRENT   READY   AGE   CONTAINERS   IMAGES                                                          SELECTOR
3 nginx-deployment-76b9d6bcf5   3         3         2       17s   nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.1   app=nginx,pod-template-hash=76b9d6bcf5

参数说明:

  • NAME:列出集群中 ReplicaSet的名称
  • DESIRED:期望副本数
  • CURRENT:当前副本数
  • READY:已就绪副本数
  • AGE:运行时间

查看pod状态

1 [root@k8s-master controller]# kubectl get pod -o wide
2 NAME                                READY   STATUS              RESTARTS   AGE   IP            NODE         NOMINATED NODE   READINESS GATES
3 nginx-deployment-76b9d6bcf5-ngpg5   1/1     Running             0          26s   10.244.2.43   k8s-node02   <none>           <none>
4 nginx-deployment-76b9d6bcf5-rw827   1/1     Running             0          26s   10.244.2.44   k8s-node02   <none>           <none>
5 nginx-deployment-76b9d6bcf5-ttf4j   0/1     ContainerCreating   0          26s   <none>        k8s-node01   <none>           <none>

过一会儿状态说明

 1 [root@k8s-master controller]# kubectl get deployment -o wide --show-labels
 2 NAME               READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES                                                          SELECTOR    LABELS
 3 nginx-deployment   3/3     3            3           23m   nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.1   app=nginx   app=nginx
 4 [root@k8s-master controller]# 
 5 [root@k8s-master controller]# kubectl get rs -o wide --show-labels
 6 NAME                          DESIRED   CURRENT   READY   AGE   CONTAINERS   IMAGES                                                          SELECTOR                                 LABELS
 7 nginx-deployment-76b9d6bcf5   3         3         3       23m   nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.1   app=nginx,pod-template-hash=76b9d6bcf5   app=nginx,pod-template-hash=76b9d6bcf5
 8 [root@k8s-master controller]# 
 9 [root@k8s-master controller]# kubectl get pod -o wide --show-labels
10 NAME                                READY   STATUS    RESTARTS   AGE   IP            NODE         NOMINATED NODE   READINESS GATES   LABELS
11 nginx-deployment-76b9d6bcf5-ngpg5   1/1     Running   0          23m   10.244.2.43   k8s-node02   <none>           <none>            app=nginx,pod-template-hash=76b9d6bcf5
12 nginx-deployment-76b9d6bcf5-rw827   1/1     Running   0          23m   10.244.2.44   k8s-node02   <none>           <none>            app=nginx,pod-template-hash=76b9d6bcf5
13 nginx-deployment-76b9d6bcf5-ttf4j   1/1     Running   0          23m   10.244.4.37   k8s-node01   <none>           <none>            app=nginx,pod-template-hash=76b9d6bcf5

重点说明

1、ReplicaSet 的名称始终被格式化为[DEPLOYMENT-NAME]-[RANDOM-STRING]。随机字符串是随机生成,并使用 pod-template-hash 作为选择器和标签。

2、Deployment 控制器将 pod-template-hash 标签添加到 Deployment 创建或使用的每个 ReplicaSet 。此标签可确保 Deployment 的子 ReplicaSets 不重叠。因此不可修改。

3、注意Deployment、ReplicaSet和Pod三者的名称关系

更新 Deployment

Deployment 可确保在更新时仅关闭一定数量的 Pods。默认情况下,它确保至少 75%所需 Pods 运行(25%最大不可用)。

Deployment 更新过程中还确保仅创建一定数量的 Pods 且高于期望的 Pods 数。默认情况下,它可确保最多增加 25% 期望 Pods 数(25%最大增量)。

备注:实际操作中如果更新Deployment,那么最好通过yaml文件更新,这样回滚到任何版本都非常便捷,而且更容易追述;而不是通过命令行。

如下Deployment示例,由于只有3个副本。因此更新时不会先删除旧的pod,而是先新建一个pod。新pod运行时,才会删除对应老的pod。一切的前提都是为了满足上述的条件。

需求:更新 nginx Pods,从当前的1.17.1版本改为1.17.5版本。

 1 # 方式一
 2 kubectl edit deployment/nginx-deployment    # 然后修改 image 镜像信息 【不推荐】
 3 # 上述方法不会记录命令,通过kubectl rollout history deployment/nginx-deployment 无法查询
 4 
 5 # 方式二如下【可使用】:
 6 kubectl set image deployment/nginx-deployment nginx=registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.5 --record 
 7 
 8 # 方式三如下【推荐★★★★★】
 9 kubectl apply -f nginx-deployment-1.17.5.yaml --record
10 
11 # --record 参数可以记录命令,通过 kubectl rollout history deployment/nginx-deployment 可查询

要查看更新状态

 1 [root@k8s-master controller]# kubectl rollout status deployment/nginx-deployment
 2 # 如没有更新完成,则显示更新过程直到更新成功
 3 Waiting for deployment "nginx-deployment" rollout to finish: 1 out of 3 new replicas have been updated...
 4 Waiting for deployment "nginx-deployment" rollout to finish: 1 out of 3 new replicas have been updated...
 5 Waiting for deployment "nginx-deployment" rollout to finish: 2 out of 3 new replicas have been updated...
 6 Waiting for deployment "nginx-deployment" rollout to finish: 2 out of 3 new replicas have been updated...
 7 Waiting for deployment "nginx-deployment" rollout to finish: 2 out of 3 new replicas have been updated...
 8 Waiting for deployment "nginx-deployment" rollout to finish: 1 old replicas are pending termination...
 9 Waiting for deployment "nginx-deployment" rollout to finish: 1 old replicas are pending termination...
10 deployment "nginx-deployment" successfully rolled out
11 # 如已更新完毕,直接显示更新成功
12 deployment "nginx-deployment" successfully rolled out

更新中的Deployment、ReplicaSet、Pod信息

 1 [root@k8s-master controller]# kubectl get deployment -o wide --show-labels
 2 NAME               READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES                                                          SELECTOR    LABELS
 3 nginx-deployment   3/3     1            3           12m   nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.5   app=nginx   app=nginx
 4 [root@k8s-master controller]# 
 5 [root@k8s-master controller]# kubectl get rs -o wide --show-labels
 6 NAME                          DESIRED   CURRENT   READY   AGE   CONTAINERS   IMAGES                                                          SELECTOR                                 LABELS
 7 nginx-deployment-56d78686f5   1         1         0       23s   nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.5   app=nginx,pod-template-hash=56d78686f5   app=nginx,pod-template-hash=56d78686f5
 8 nginx-deployment-76b9d6bcf5   3         3         3       12m   nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.1   app=nginx,pod-template-hash=76b9d6bcf5   app=nginx,pod-template-hash=76b9d6bcf5
 9 [root@k8s-master controller]# 
10 [root@k8s-master controller]# kubectl get pod -o wide --show-labels
11 NAME                                READY   STATUS              RESTARTS   AGE   IP            NODE         NOMINATED NODE   READINESS GATES   LABELS
12 nginx-deployment-56d78686f5-4kn4c   0/1     ContainerCreating   0          30s   <none>        k8s-node02   <none>           <none>            app=nginx,pod-template-hash=56d78686f5
13 nginx-deployment-76b9d6bcf5-7lcr9   1/1     Running             0          12m   10.244.4.41   k8s-node01   <none>           <none>            app=nginx,pod-template-hash=76b9d6bcf5
14 nginx-deployment-76b9d6bcf5-jbb5h   1/1     Running             0          12m   10.244.2.48   k8s-node02   <none>           <none>            app=nginx,pod-template-hash=76b9d6bcf5
15 nginx-deployment-76b9d6bcf5-rt4m7   1/1     Running             0          12m   10.244.4.42   k8s-node01   <none>           <none>            app=nginx,pod-template-hash=76b9d6bcf5

更新成功后的Deployment、ReplicaSet、Pod信息

 1 [root@k8s-master controller]# kubectl get deployment -o wide --show-labels
 2 NAME               READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES                                                          SELECTOR    LABELS
 3 nginx-deployment   3/3     3            3           15m   nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.5   app=nginx   app=nginx
 4 [root@k8s-master controller]# 
 5 [root@k8s-master controller]# kubectl get rs -o wide --show-labels
 6 NAME                          DESIRED   CURRENT   READY   AGE     CONTAINERS   IMAGES                                                          SELECTOR                                 LABELS
 7 nginx-deployment-56d78686f5   3         3         3       3m23s   nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.5   app=nginx,pod-template-hash=56d78686f5   app=nginx,pod-template-hash=56d78686f5
 8 nginx-deployment-76b9d6bcf5   0         0         0       15m     nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.1   app=nginx,pod-template-hash=76b9d6bcf5   app=nginx,pod-template-hash=76b9d6bcf5
 9 [root@k8s-master controller]# 
10 [root@k8s-master controller]# kubectl get pod -o wide --show-labels
11 NAME                                READY   STATUS    RESTARTS   AGE     IP            NODE         NOMINATED NODE   READINESS GATES   LABELS
12 nginx-deployment-56d78686f5-4kn4c   1/1     Running   0          3m25s   10.244.2.49   k8s-node02   <none>           <none>            app=nginx,pod-template-hash=56d78686f5
13 nginx-deployment-56d78686f5-khsnm   1/1     Running   0          100s    10.244.2.50   k8s-node02   <none>           <none>            app=nginx,pod-template-hash=56d78686f5
14 nginx-deployment-56d78686f5-t24qw   1/1     Running   0          2m44s   10.244.4.43   k8s-node01   <none>           <none>            app=nginx,pod-template-hash=56d78686f5

通过查询Deployment详情,知晓pod替换过程

 1 [root@k8s-master controller]# kubectl describe deploy nginx-deployment
 2 Name:                   nginx-deployment
 3 Namespace:              default
 4 CreationTimestamp:      Thu, 28 May 2020 00:04:09 +0800
 5 Labels:                 app=nginx
 6 Annotations:            deployment.kubernetes.io/revision: 2
 7                         kubectl.kubernetes.io/last-applied-configuration:
 8                           {"apiVersion":"apps/v1","kind":"Deployment","metadata":{"annotations":{"kubernetes.io/change-cause":"kubectl apply --filename=nginx-deploy...
 9                         kubernetes.io/change-cause:
10                           kubectl set image deployment/nginx-deployment nginx=registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.5 --record=true
11 Selector:               app=nginx
12 Replicas:               3 desired | 3 updated | 3 total | 3 available | 0 unavailable
13 StrategyType:           RollingUpdate
14 MinReadySeconds:        0
15 RollingUpdateStrategy:  25% max unavailable, 25% max surge
16 Pod Template:
17   Labels:  app=nginx
18   Containers:
19    nginx:
20     Image:        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.5
21     Port:         80/TCP
22     Host Port:    0/TCP
23     Environment:  <none>
24     Mounts:       <none>
25   Volumes:        <none>
26 Conditions:
27   Type           Status  Reason
28   ----           ------  ------
29   Available      True    MinimumReplicasAvailable
30   Progressing    True    NewReplicaSetAvailable
31 OldReplicaSets:  <none>
32 NewReplicaSet:   nginx-deployment-56d78686f5 (3/3 replicas created)
33 Events:
34   Type    Reason             Age   From                   Message
35   ----    ------             ----  ----                   -------
36   Normal  ScalingReplicaSet  93s   deployment-controller  Scaled up replica set nginx-deployment-76b9d6bcf5 to 3
37   Normal  ScalingReplicaSet  38s   deployment-controller  Scaled up replica set nginx-deployment-56d78686f5 to 1
38   Normal  ScalingReplicaSet  37s   deployment-controller  Scaled down replica set nginx-deployment-76b9d6bcf5 to 2
39   Normal  ScalingReplicaSet  37s   deployment-controller  Scaled up replica set nginx-deployment-56d78686f5 to 2
40   Normal  ScalingReplicaSet  35s   deployment-controller  Scaled down replica set nginx-deployment-76b9d6bcf5 to 1
41   Normal  ScalingReplicaSet  35s   deployment-controller  Scaled up replica set nginx-deployment-56d78686f5 to 3
42   Normal  ScalingReplicaSet  34s   deployment-controller  Scaled down replica set nginx-deployment-76b9d6bcf5 to 0

多 Deployment 动态更新

当 Deployment 正在展开进行更新时,Deployment 会为每个更新创建一个新的 ReplicaSet 并开始向上扩展,之前的 ReplicaSet 会被添加到旧 ReplicaSets 队列并开始向下扩展。

例如,假设创建一个 Deployment 以创建 nginx:1.7.9 的 5 个副本,然后更新 Deployment 以创建 5 个 nginx:1.9.1 的副本,而此时只有 3 个nginx:1.7.9 的副本已创建。在这种情况下, Deployment 会立即开始杀死3个 nginx:1.7.9 Pods,并开始创建 nginx:1.9.1 Pods。它不等待 nginx:1.7.9 的 5 个副本完成后再更新为nginx:1.9.1。

回滚 Deployment

yaml文件方式

针对应用的每个镜像版本,都有对应deploy的yaml文件。不管是升级还是回滚都已轻松应对。如下

1 nginx-deployment-1.15.6.yaml
2 nginx-deployment-1.17.yaml
3 nginx-deployment-1.17.1.yaml
4 nginx-deployment-1.17.5.yaml

yaml文件中的信息,参考上文即可。

命令行方式

问题产生

假设在更新 Deployment 时犯了一个拼写错误,将镜像名称命名为了 nginx:1.1710 而不是 nginx:1.17.10

1 [root@k8s-master controller]# kubectl set image deployment/nginx-deployment nginx=registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.1710 --record
2 deployment.apps/nginx-deployment image updated

查看Deployment、ReplicaSet、Pod信息

 1 [root@k8s-master controller]# kubectl get deploy -o wide --show-labels
 2 NAME               READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES                                                          SELECTOR    LABELS
 3 nginx-deployment   3/3     1            3           14m   nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.1710   app=nginx   app=nginx
 4 [root@k8s-master controller]#
 5 [root@k8s-master controller]# kubectl get rs -o wide --show-labels
 6 NAME                          DESIRED   CURRENT   READY   AGE     CONTAINERS   IMAGES                                                          SELECTOR                                 LABELS
 7 nginx-deployment-55c7bdfb86   3         3         3       9m19s   nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17     app=nginx,pod-template-hash=55c7bdfb86   app=nginx,pod-template-hash=55c7bdfb86
 8 nginx-deployment-56d78686f5   0         0         0       12m     nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.5   app=nginx,pod-template-hash=56d78686f5   app=nginx,pod-template-hash=56d78686f5
 9 nginx-deployment-76b9d6bcf5   0         0         0       13m     nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.1   app=nginx,pod-template-hash=76b9d6bcf5   app=nginx,pod-template-hash=76b9d6bcf5
10 nginx-deployment-844d7bbb7f   1         1         0       64s     nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.1710   app=nginx,pod-template-hash=844d7bbb7f   app=nginx,pod-template-hash=844d7bbb7f
11 [root@k8s-master controller]#
12 [root@k8s-master controller]# kubectl get pod -o wide --show-labels
13 NAME                                READY   STATUS             RESTARTS   AGE    IP            NODE         NOMINATED NODE   READINESS GATES   LABELS
14 nginx-deployment-55c7bdfb86-bwzk9   1/1     Running            0          10m    10.244.4.49   k8s-node01   <none>           <none>            app=nginx,pod-template-hash=55c7bdfb86
15 nginx-deployment-55c7bdfb86-cmvzg   1/1     Running            0          10m    10.244.2.55   k8s-node02   <none>           <none>            app=nginx,pod-template-hash=55c7bdfb86
16 nginx-deployment-55c7bdfb86-kjrrw   1/1     Running            0          10m    10.244.2.56   k8s-node02   <none>           <none>            app=nginx,pod-template-hash=55c7bdfb86
17 nginx-deployment-844d7bbb7f-pctwr   0/1     ImagePullBackOff   0          2m3s   10.244.4.51   k8s-node01   <none>           <none>            app=nginx,pod-template-hash=844d7bbb7f

需求:回滚到以前稳定的 Deployment 版本。

操作步骤如下:

检查 Deployment 修改历史

1 [root@k8s-master controller]# kubectl rollout history deployment/nginx-deployment
2 deployment.apps/nginx-deployment 
3 REVISION  CHANGE-CAUSE
4 1         kubectl apply --filename=nginx-deployment.yaml --record=true
5 2         kubectl set image deployment/nginx-deployment nginx=registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.5 --record=true
6 3         kubectl set image deployment/nginx-deployment nginx=registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17 --record=true
7 4         kubectl set image deployment/nginx-deployment nginx=registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.1710 --record=true

查看修改历史的详细信息,运行

 1 [root@k8s-master controller]# kubectl rollout history deployment/nginx-deployment --revision=3
 2 deployment.apps/nginx-deployment with revision #3
 3 Pod Template:
 4   Labels:    app=nginx
 5     pod-template-hash=55c7bdfb86
 6   Annotations:    kubernetes.io/change-cause:
 7       kubectl set image deployment/nginx-deployment nginx=registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17 --record=true
 8   Containers:
 9    nginx:
10     Image:    registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17
11     Port:    80/TCP
12     Host Port:    0/TCP
13     Environment:    <none>
14     Mounts:    <none>
15   Volumes:    <none>

回滚到上一次修改(即版本 3)或指定版本

现在已决定撤消当前更新并回滚到以前的版本

1 # 回滚到上一版本
2 [root@k8s-master controller]# kubectl rollout undo deployment/nginx-deployment
3 deployment.apps/nginx-deployment rolled back
4 # 回滚到指定历史版本
5 [root@k8s-master controller]# kubectl rollout undo deployment/nginx-deployment --to-revision=2
6 deployment.apps/nginx-deployment rolled back

检查回滚是否成功、 Deployment 是否正在运行

1 [root@k8s-master controller]# kubectl get deploy -o wide --show-labels
2 NAME               READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES                                                          SELECTOR    LABELS
3 nginx-deployment   3/3     3            3           17h   nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.5   app=nginx   app=nginx

获取 Deployment 描述信息

 1 [root@k8s-master controller]# kubectl describe deployment
 2 Name:                   nginx-deployment
 3 Namespace:              default
 4 CreationTimestamp:      Thu, 28 May 2020 00:04:09 +0800
 5 Labels:                 app=nginx
 6 Annotations:            deployment.kubernetes.io/revision: 7
 7                         kubectl.kubernetes.io/last-applied-configuration:
 8                           {"apiVersion":"apps/v1","kind":"Deployment","metadata":{"annotations":{"kubernetes.io/change-cause":"kubectl apply --filename=nginx-deploy...
 9                         kubernetes.io/change-cause:
10                           kubectl set image deployment/nginx-deployment nginx=registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.5 --record=true
11 Selector:               app=nginx
12 Replicas:               3 desired | 3 updated | 3 total | 3 available | 0 unavailable
13 StrategyType:           RollingUpdate
14 MinReadySeconds:        0
15 RollingUpdateStrategy:  25% max unavailable, 25% max surge
16 Pod Template:
17   Labels:  app=nginx
18   Containers:
19    nginx:
20     Image:        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.5
21     Port:         80/TCP
22     Host Port:    0/TCP
23     Environment:  <none>
24     Mounts:       <none>
25   Volumes:        <none>
26 Conditions:
27   Type           Status  Reason
28   ----           ------  ------
29   Available      True    MinimumReplicasAvailable
30   Progressing    True    NewReplicaSetAvailable
31 OldReplicaSets:  <none>
32 NewReplicaSet:   nginx-deployment-56d78686f5 (3/3 replicas created)
33 Events:
34   Type    Reason             Age                 From                   Message
35   ----    ------             ----                ----                   -------
36 ………………
37   Normal  ScalingReplicaSet  107s                deployment-controller  Scaled up replica set nginx-deployment-56d78686f5 to 1
38   Normal  ScalingReplicaSet  104s                deployment-controller  Scaled down replica set nginx-deployment-55c7bdfb86 to 2
39   Normal  ScalingReplicaSet  104s                deployment-controller  Scaled up replica set nginx-deployment-56d78686f5 to 2
40   Normal  ScalingReplicaSet  103s                deployment-controller  Scaled down replica set nginx-deployment-55c7bdfb86 to 1
41   Normal  ScalingReplicaSet  103s                deployment-controller  Scaled up replica set nginx-deployment-56d78686f5 to 3
42   Normal  ScalingReplicaSet  102s                deployment-controller  Scaled down replica set nginx-deployment-55c7bdfb86 to 0

扩容/缩容Deployment

操作过程如下

 1 [root@k8s-master controller]# kubectl scale deployment/nginx-deployment --replicas=10
 2 deployment.apps/nginx-deployment scaled
 3 [root@k8s-master controller]# kubectl get deploy -o wide --show-labels
 4 NAME               READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES                                                          SELECTOR    LABELS
 5 nginx-deployment   10/10   10           10          17h   nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.5   app=nginx   app=nginx
 6 [root@k8s-master controller]# 
 7 [root@k8s-master controller]# kubectl get rs -o wide --show-labels
 8 NAME                          DESIRED   CURRENT   READY   AGE   CONTAINERS   IMAGES                                                          SELECTOR                                 LABELS
 9 nginx-deployment-55c7bdfb86   0         0         0       17h   nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17     app=nginx,pod-template-hash=55c7bdfb86   app=nginx,pod-template-hash=55c7bdfb86
10 nginx-deployment-56d78686f5   10        10        10      17h   nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.5   app=nginx,pod-template-hash=56d78686f5   app=nginx,pod-template-hash=56d78686f5
11 nginx-deployment-76b9d6bcf5   0         0         0       17h   nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17.1   app=nginx,pod-template-hash=76b9d6bcf5   app=nginx,pod-template-hash=76b9d6bcf5
12 nginx-deployment-844d7bbb7f   0         0         0       17h   nginx        registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.1710   app=nginx,pod-template-hash=844d7bbb7f   app=nginx,pod-template-hash=844d7bbb7f
13 [root@k8s-master controller]# 
14 [root@k8s-master controller]# kubectl get pod -o wide --show-labels
15 NAME                                READY   STATUS    RESTARTS   AGE   IP            NODE         NOMINATED NODE   READINESS GATES   LABELS
16 nginx-deployment-56d78686f5-4v5mj   1/1     Running   0          44s   10.244.2.64   k8s-node02   <none>           <none>            app=nginx,pod-template-hash=56d78686f5
17 nginx-deployment-56d78686f5-8m7mx   1/1     Running   0          44s   10.244.4.60   k8s-node01   <none>           <none>            app=nginx,pod-template-hash=56d78686f5
18 nginx-deployment-56d78686f5-c7wlb   1/1     Running   0          44s   10.244.4.59   k8s-node01   <none>           <none>            app=nginx,pod-template-hash=56d78686f5
19 nginx-deployment-56d78686f5-jg5lt   1/1     Running   0          44s   10.244.2.63   k8s-node02   <none>           <none>            app=nginx,pod-template-hash=56d78686f5
20 nginx-deployment-56d78686f5-jj58d   1/1     Running   0          11m   10.244.4.56   k8s-node01   <none>           <none>            app=nginx,pod-template-hash=56d78686f5
21 nginx-deployment-56d78686f5-k2kts   1/1     Running   0          11m   10.244.4.57   k8s-node01   <none>           <none>            app=nginx,pod-template-hash=56d78686f5
22 nginx-deployment-56d78686f5-qltkv   1/1     Running   0          44s   10.244.2.61   k8s-node02   <none>           <none>            app=nginx,pod-template-hash=56d78686f5
23 nginx-deployment-56d78686f5-r7vmm   1/1     Running   0          11m   10.244.2.60   k8s-node02   <none>           <none>            app=nginx,pod-template-hash=56d78686f5
24 nginx-deployment-56d78686f5-rxlpm   1/1     Running   0          44s   10.244.2.62   k8s-node02   <none>           <none>            app=nginx,pod-template-hash=56d78686f5
25 nginx-deployment-56d78686f5-vlzrf   1/1     Running   0          44s   10.244.4.58   k8s-node01   <none>           <none>            app=nginx,pod-template-hash=56d78686f5

清理策略Policy

可以在 Deployment 中设置 .spec.revisionHistoryLimit,以指定保留多少该 Deployment 的 ReplicaSets数量。其余的将在后台进行垃圾回收。默认情况下,是10。

注意:此字段设置为 0 将导致清理 Deployment 的所有历史记录,因此 Deployment 将无法通过命令行回滚。

相关阅读

1、Kubernetes K8S之kubectl命令详解及常用示例

完毕!


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