一、实验环境准备：

kubectl get pods -o wide
kubectl get nodes -o wide
kubectl get svc

准备两个nginx镜像，版本号一个是V3，一个是V4

二、准备一个nginx.yaml文件

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deploy
  labels:
    release: v1
spec:
  replicas: 1
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 25%
      maxSurge: 25%
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: mynginx
        image: 192.168.206.137/library/nginx:v3
        ports:
        - containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  name: nginxservice
spec:
  type: NodePort
  ports:
  - port: 80
    targetPort: 80
    nodePort: 30080
  selector:
    app: nginx1

在这个文件中，定义了：

元数据的名称为：nginx-deploy

副本数量为：1

滚动升级的策略为：RollingUpdate

滚动升级最低保留的副本数量为：25%

镜像为：192.168.206.137/library/nginx:v3

集群内部访问端口为：80

外部访问端口为：30080

三、部署这个yaml，并查看部署状态

kubectl apply -f nginx.yaml

部署状态：

kubectl rollout status deploy nginx-deploy

查看历史升级状态：

kubectl rollout history deploy nginx-deploy

查看历史升级状态为1的详细信息：

kubectl rollout history deploy nginx-deploy  --revision=1

查看发布完成后的svc和pod状态：

kubectl get svc,pods -o wide

此时可以看到，nginx.yaml已经部署完成。

四、更新nginx版本，重新发布

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deploy
  labels:
    release: v2
spec:
  replicas: 2
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 25%
      maxSurge: 25%
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: mynginx
        image: 192.168.206.137/library/nginx:v4
        ports:
        - containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  name: nginxservice
spec:
  type: NodePort
  ports:
  - port: 80
    targetPort: 80
    nodePort: 30080
  selector:
    app: nginx2

比较上面的V1版本，V2更新了几点：

副本数量增加为：2

镜像使用：v4

更新发布这个新的版本：

kubectl apply -f nginx.yaml
kubectl rollout status deploy nginx-deploy

跟新后的SVC和POD状态：

可以看到POD增加到了2个

再次查看历史更新记录：

kubectl rollout history deploy nginx-deploy

指定查看V2的详细信息：

kubectl rollout history deploy nginx-deploy  --revision=2

这里可以看到，两次的版本更新操作，这里都有详细记录。但是这里最多只能记录2个。

五、回滚版本到V1：

v1只有一个pod并且镜像使用的是nginx:v3

撤销上一次升级，并查看升级状态：

kubectl  rollout undo deploy  nginx-deploy
kubectl rollout status deploy nginx-deploy
kubectl get svc,pods -o wide

这里会发现，原本1个的POD，回滚后变成了2个。其实这里是k8s滚动升级的机制导致的。前面设置了最低保留25%的可用性，那么至少也有1个POD。所以K8s首先新增了一个POD，然后再升级版本，最后保持两个POD一致。 

再次查看升级历史信息：

kubectl rollout history deploy nginx-deploy

查看3的详细信息：

kubectl rollout history deploy nginx-deploy  --revision=3

对比2：

kubectl rollout history deploy nginx-deploy  --revision=2

查看当前POD的详细信息：

kubectl describe pods nginx-deploy-6b6f9ff985-xpz94

Name:         nginx-deploy-6b6f9ff985-xpz94
Namespace:    default
Priority:     0
Node:         master/192.168.206.138
Start Time:   Sat, 27 Jan 2024 12:56:23 +0800
Labels:       app=nginx
              pod-template-hash=6b6f9ff985
Annotations:  cni.projectcalico.org/containerID: 1b2e98f76f8f8e7da439c4a767ec4b297035ca582bcdd445e816e1c13c3d891a
              cni.projectcalico.org/podIP: 10.224.219.80/32
              cni.projectcalico.org/podIPs: 10.224.219.80/32
Status:       Running
IP:           10.224.219.80
IPs:
  IP:           10.224.219.80
Controlled By:  ReplicaSet/nginx-deploy-6b6f9ff985
Containers:
  mynginx:
    Container ID:   docker://2e6181cee6a4886c0892af0b92b0f31bde4d3513b0d34a654a9a0e0438274c73
    Image:          192.168.206.137/library/nginx:v3
    Image ID:       docker-pullable://192.168.206.137/library/nginx@sha256:37bb5a5a2078bd67b1be281165e9f82f6f267d6404e0ae11b3a524b8fff8354e
    Port:           80/TCP
    Host Port:      0/TCP
    State:          Running
      Started:      Sat, 27 Jan 2024 12:56:24 +0800
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-gd949 (ro)
Conditions:
  Type              Status
  Initialized       True
  Ready             True
  ContainersReady   True
  PodScheduled      True
Volumes:
  default-token-gd949:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-gd949
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
                 node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
  Type    Reason     Age    From             Message
  ----    ------     ----   ----             -------
  Normal  Scheduled  5m17s                   Successfully assigned default/nginx-deploy-6b6f9ff985-xpz94 to master
  Normal  Pulled     5m17s  kubelet, master  Container image "192.168.206.137/library/nginx:v3" already present on machine
  Normal  Created    5m17s  kubelet, master  Created container mynginx
  Normal  Started    5m17s  kubelet, master  Started container mynginx

Image这个地方，可以看到当前POD使用的版本号为V3，可以说明撤销成功，已经回退都发布之前的版本。

六、回滚到指定版本：

kubectl rollout history deploy nginx-deplo

目前有两个版本，在使用的是3，可以回滚到指定版本2，镜像回滚到nginx:v4状态，副本数量为2个

kubectl rollout undo deploy nginx-deploy --to-revision=2
kubectl rollout status deploy nginx-deploy
kubectl get svc,pods -o wide
kubectl describe pods nginx-deploy-76d4c4c684-kvtx8