k8s deployment控制器：滚动升级 平滑过渡 零停机

1. 滚动升级

• 滚动升级架构图
  

• 滚动升级注释：

  ​ K8s对Pod升级的默认策略，通过使用新版本Pod逐步更新旧版本Pod，实现零停机发布，用户无感知。

• 滚动升级更新策略：

  [root@k8s-master deployment]# vim web.yaml 
  [root@k8s-master deployment]# cat web.yaml 
  apiVersion: apps/v1
  kind: Deployment
  metadata:
    name: web
    namespace: default
    annotations:       # 记录回滚参数
      kubernetes.io/change-cause: "web.v1-nginx-1.19"   #记录到revision中的内容，记录版本号
  spec:
    replicas: 9 # Pod副本预期数量
    revisionHistoryLimit: 10 # RS历史版本保存数量
    selector:
      matchLabels:
        app: web
    strategy:
      rollingUpdate:
        maxSurge: 25%             # 滚动更新过程最大pod副本数
        maxUnavailable: 25%       # 滚动更新过程中最大不可用pod副本数，
      type: RollingUpdate
    template:
      metadata:
        labels:
          app: web # Pod副本的标签
      spec:
        containers:
        - name: web
          image: nginx:1.19
          readinessProbe:          # 存活检查,如果失败，将杀死容器，来重启
            httpGet:
              port: 80
              path: /index.html
            initialDelaySeconds: 10 #启动容器后多少秒健康检查
            periodSeconds: 10 #以后间隔多少秒检查一次
  
          livenessProbe:   # 就绪检查，失败就会剔除 service 
            httpGet:
              port: 80
              path: /index.html
  
  

  • 注释
    1. maxSurge：滚动更新过程中最大Pod副本数，确保在更新时启动的Pod数量比期望（replicas）Pod数量最大多出25%
    2. maxUnavailable：滚动更新过程中最大不可用Pod副本数，确保在更新时最大25%Pod数量不可用，即确保75%Pod数量是可用状态。

2. 滚动升级操作

kubectl apply -f xxx.yaml
kubectl set image deployment/web nginx=nginx:1.16
kubectl edit deployment/web

3. 案例

3.1 编写deployment的web.yaml文件

[root@k8s-master deployment]# vim web.yaml 
[root@k8s-master deployment]# cat web.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: web
  namespace: default
  annotations:       # 记录回滚参数
    kubernetes.io/change-cause: "web.v1-nginx-1.19"   #记录到revision中的内容，记录版本号
spec:
  replicas: 9 # Pod副本预期数量
  revisionHistoryLimit: 10 # RS历史版本保存数量
  selector:
    matchLabels:
      app: web
  strategy:
    rollingUpdate:
      maxSurge: 25%             # 滚动更新过程最大pod副本数
      maxUnavailable: 25%       # 滚动更新过程中最大不可用pod副本数，
    type: RollingUpdate
  template:
    metadata:
      labels:
        app: web # Pod副本的标签
    spec:
      containers:
      - name: web
        image: nginx:1.16
        readinessProbe:          # 存活检查,如果失败，将杀死容器，来重启
          httpGet:
            port: 80
            path: /index.html
          initialDelaySeconds: 10 #启动容器后多少秒健康检查
          periodSeconds: 10 #以后间隔多少秒检查一次

        livenessProbe:   # 就绪检查，失败就会剔除 service 
          httpGet:
            port: 80
            path: /index.html

3.2 启动服务

[root@k8s-master deployment]# kubectl apply -f web.yaml 
deployment.apps/web created

3.3 查看服务

[root@k8s-master deployment]# kubectl get pods
NAME                   READY   STATUS    RESTARTS   AGE
web-548b65b8c6-4k8n7   1/1     Running   0          2m24s
web-548b65b8c6-7wvhj   1/1     Running   0          2m24s
web-548b65b8c6-vpmpg   1/1     Running   0          2m24s
[root@k8s-master deployment]# kubectl get pods -o wide
NAME                   READY   STATUS    RESTARTS   AGE     IP               NODE        NOMINATED NODE   READINESS GATES
web-548b65b8c6-4k8n7   1/1     Running   0          2m56s   10.244.36.96     k8s-node1   <none>           <none>
web-548b65b8c6-7wvhj   1/1     Running   0          2m56s   10.244.169.159   k8s-node2   <none>           <none>
web-548b65b8c6-vpmpg   1/1     Running   0          2m56s   10.244.36.95     k8s-node1   <none>           <none>

3.4 deployment端口暴露

[root@k8s-master deployment]# kubectl expose deployment web --port=80 --target-port=80 --type=NodePort
service/web exposed

3.5 查询服务是否端口暴露

[root@k8s-master deployment]# kubectl get service 
NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
kubernetes   ClusterIP   10.96.0.1        <none>        443/TCP        6d
probe-demo   ClusterIP   10.104.161.168   <none>        80/TCP         2d
web          NodePort    10.98.32.199     <none>        80:30082/TCP   14s

3.6 curl请求测试

[root@k8s-master deployment]# curl -I http://192.168.0.202:30082
HTTP/1.1 200 OK
Server: nginx/1.16.1
Date: Tue, 01 Dec 2020 08:28:06 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Tue, 13 Aug 2019 10:05:00 GMT
Connection: keep-alive
ETag: "5d528b4c-264"
Accept-Ranges: bytes

3.7 修改deployment的web.yaml文件实现滚动更新

[root@k8s-master deployment]# vim web.yaml [root@k8s-master deployment]# cat web.yaml apiVersion: apps/v1kind: Deploymentmetadata:  name: web  namespace: default  annotations:       # 记录回滚参数    kubernetes.io/change-cause: "web.v1-nginx-1.19"   #记录到revision中的内容，记录版本号spec:  replicas: 9 # Pod副本预期数量  revisionHistoryLimit: 10 # RS历史版本保存数量  selector:    matchLabels:      app: web  strategy:    rollingUpdate:      maxSurge: 25%             # 滚动更新过程最大pod副本数      maxUnavailable: 25%       # 滚动更新过程中最大不可用pod副本数，    type: RollingUpdate  template:    metadata:      labels:        app: web # Pod副本的标签    spec:      containers:      - name: web        image: nginx:1.18        readinessProbe:          # 存活检查,如果失败，将杀死容器，来重启          httpGet:            port: 80            path: /index.html          initialDelaySeconds: 10 #启动容器后多少秒健康检查          periodSeconds: 10 #以后间隔多少秒检查一次        livenessProbe:   # 就绪检查，失败就会剔除 service           httpGet:            port: 80            path: /index.html

3.8 执行配置文件更新

[root@k8s-master deployment]# kubectl apply -f web.yaml deployment.apps/web configured

3.9 查看pod服务

[root@k8s-master deployment]# kubectl get podsNAME                   READY   STATUS              RESTARTS   AGEweb-65798c9f74-2r266   0/1     Terminating         0          39mweb-65798c9f74-5hl4p   1/1     Running             0          39mweb-65798c9f74-5qhgg   1/1     Running             0          39mweb-79c4bc4bd-9j4pw    0/1     ContainerCreating   0          3sweb-79c4bc4bd-pbz5m    1/1     Running             0          30s

3.10 curl 请求是否nginx是1.18版本

[root@k8s-master deployment]# curl -I http://192.168.0.202:30082HTTP/1.1 200 OKServer: nginx/1.18.0Date: Tue, 01 Dec 2020 08:31:09 GMTContent-Type: text/htmlContent-Length: 612Last-Modified: Tue, 21 Apr 2020 14:09:01 GMTConnection: keep-aliveETag: "5e9efe7d-264"Accept-Ranges: bytes