1、什么是controller

• 在集群上管理和运行容器的对象

2、 pod和controller关系

• pod是通过Controller实现应用的运维，比如伸缩、滚动升级等
• pod和Controller之间通过label建立关系。通过下图进行深刻理解

3、Deployment控制器应用场景

• 一般部署无状态应用
• 管理Pod和ReplicaSet
• 部署，滚动升级等功能
• 应用场景：web服务、微服务

3.1 部署时yaml文件书写

[root@master example]# kubectl create deployment web --image=nginx --dry-run -o yaml > web.yaml  ##生成一个示例yaml文件
[root@master example]# cat web.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:         ##控制器标签
    app: web
  name: web
spec:
  replicas: 1
  selector:   # 与pod匹配的labels
    matchLabels:
      app: web
  strategy: {}
  template:   # 模板部分是涉及到的pod
    metadata:
      creationTimestamp: null
      labels:
        app: web
    spec:
      containers:
      - image: nginx
        name: nginx
        resources: {}
status: {}

3.2 实际部署应用

[root@master example]# kubectl apply -f web.yaml    ##现在别的机器还访问不到
[root@master example]# kubectl expose --help    ## 对外发布，即暴漏端口
[root@master example]# kubectl expose deployment web --port=80 --type=NodePort --target-port=80 --name=webexpose -o yaml > webexpose.yaml   # 前面是自身端口，后面是向外暴露的端口
[root@master example]# ll webexpose.yaml 
[root@master example]# cat webexpose.yaml 
apiVersion: v1
kind: Service
metadata:
  creationTimestamp: "2022-05-05T12:57:40Z"
  labels:
    app: web
  managedFields:
  - apiVersion: v1
    fieldsType: FieldsV1
    fieldsV1:
      f:metadata:
        f:labels:
          .: {}
          f:app: {}
      f:spec:
        f:externalTrafficPolicy: {}
        f:ports:
          .: {}
          k:{"port":80,"protocol":"TCP"}:
            .: {}
            f:port: {}
            f:protocol: {}
            f:targetPort: {}
        f:selector:
          .: {}
          f:app: {}
        f:sessionAffinity: {}
        f:type: {}
    manager: kubectl-expose
    operation: Update
    time: "2022-05-05T12:57:40Z"
  name: webexpose
  namespace: default
  resourceVersion: "184540"
  uid: b79e14cb-2b1b-44c1-b626-f4903786fb8a
spec:
  clusterIP: 10.103.24.195
  clusterIPs:
  - 10.103.24.195
  externalTrafficPolicy: Cluster
  ports:
  - nodePort: 30605
    port: 80
    protocol: TCP
    targetPort: 80
  selector:
    app: web
  sessionAffinity: None
  type: NodePort
status:
  loadBalancer: {}
[root@master example]# kubectl get pods,svc   #svc是services的缩写
NAME                      READY   STATUS    RESTARTS   AGE
pod/mypod                 1/1     Running   0          10h
pod/nginx                 1/1     Running   1          27h
pod/web-96d5df5c8-kkmsz   1/1     Running   0          10m

NAME                 TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
service/kubernetes   ClusterIP   10.96.0.1       <none>        443/TCP        57d
service/webexpose    NodePort    10.103.24.195   <none>        80:30605/TCP   21s

3.3 升级回滚

3.3.1 升级

# 1、最初的nginx:1.14版本
[root@master example]# vim web.yaml 
[root@master example]# cat web.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    app: web
  name: web
spec:
  replicas: 2
  selector:
    matchLabels:
      app: web
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: web
    spec:
      containers:
      - image: nginx:1.14
        name: nginx
        resources: {}
status: {}
[root@master example]# kubectl apply -f web.yaml 
deployment.apps/web created
[root@master example]# kubectl get pod
NAME                   READY   STATUS              RESTARTS   AGE
web-5bb6fd4c98-bskvw   1/1     Running             0          3s
web-5bb6fd4c98-qtv8q   0/1     ContainerCreating   0          3s
[root@master example]# kubectl get pod
NAME                   READY   STATUS    RESTARTS   AGE
web-5bb6fd4c98-bskvw   1/1     Running   0          30s
web-5bb6fd4c98-qtv8q   1/1     Running   0          30s


# 2、升级
# 升级过程中会下载新的镜像，下载成功后删除掉原来的pod，建立新的pod
[root@master example]#  kubectl set image deployment web nginx=nginx:1.15  # 升级
[root@master example]# kubectl rollout  status deployment web   #查看升级状态
deployment "web" successfully rolled out

3.3.2 回滚

[root@master example]#  kubectl rollout history deployment web   # 查看历史版本
deployment.apps/web 
REVISION  CHANGE-CAUSE
1         <none>
2         <none>

[root@master example]#  kubectl rollout undo deployment web  # 回滚到上一个版本
deployment.apps/web rolled back
[root@master example]# kubectl rollout  status deployment web   #  查看回滚状态
deployment "web" successfully rolled out
[root@master example]# kubectl get pod
NAME                   READY   STATUS    RESTARTS   AGE
web-5bb6fd4c98-hm2jt   1/1     Running   0          17s
web-5bb6fd4c98-nmjcg   1/1     Running   0          16s
[root@master example]# kubectl rollout undo --help ^C   # 查看回滚帮助
[root@master example]# kubectl rollout undo deployment web --to-revision=2  # 回滚到指定版本
deployment.apps/web rolled back
[root@master example]# kubectl rollout  status deployment web 
deployment "web" successfully rolled out

3.4 弹性伸缩

• 为了提供更多的服务

[root@master example]# kubectl scale deployment web --replicas=5
deployment.apps/web scaled
[root@master example]# kubectl get pod
NAME                  READY   STATUS    RESTARTS   AGE
web-f686c9cdf-72fhz   1/1     Running   0          4s
web-f686c9cdf-7kxgm   1/1     Running   0          4s
web-f686c9cdf-89zwq   1/1     Running   0          3m6s
web-f686c9cdf-gm6r6   1/1     Running   0          3m5s
web-f686c9cdf-q45v2   1/1     Running   0          4s