一、Deployment控制器

1.1 Deployment控制器简介

Deployment控制器并不是直接管理Pod，而是通过管理ReplicaSet来间接管理Pod，即Deployment管理ReplicaSet，ReplicaSet管理Pod，所以Deployment比ReplicaSet功能更加强大

Deployment控制器主要功能又如下几个：

支持ReplicaSet所有功能
支持发布的停止、继续
支持版本滚动升级和版本回退

1.2 Deployment的资源清单文件

deployment资源清单文件如下：

apiVersion: apps/v1  # 版本号
kind: Deployment   # 类型
metadata:   # 元数据
  name:   # rs名称
  namespace:    # 所属命名空间
  labels:   # 标签
    controller: deploy
spec:   # 详情描述
  replicas: 3  # 副本数量
  revisionHistoryLimit: 3  # 保留历史版本，默认是10
  paused: false  # 暂停部署，默认是false
  progressDeadlineSeconds: 600  # 部署超时时间，默认是600s
  strategy: # 策略
    type: RollingUpdate   # 滚动更新策略
    rollingUpdate:  # 滚动更新
      maxSurge: 30%   # 最大额外可以存在的副本数，可以为百分比，也可以为整数
      maxUnavailable: 30%  # 最大不可用状态的Pod的最大值，可以为百分比，也可以为整数
  selector: # 选择器，通过它指定该控制器管理哪些pod
    matchLabels:  # Label匹配规则
      app: nginx-pod
    matchExpressions: # Expressions匹配规则
      - {key: app, operator: In, values: [nginx-pod]}
  template: # 模板，当副本数量不足时，会根据下面的模板创建Pod副本
    metadata:
      labels:
        app: nginx-pod
    spec:
      containers:
      - name: nginx
        image: nginx:1.17.1
        ports:
        - containerPort: 80

二、Deployment控制器实例演示

编写pc_deployment.yaml文件，内容如下：

apiVersion: v1
kind: Namespace
metadata:
  name: dev
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: pc-deployment
  namespace: dev
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx-pod
  template:
    metadata:
      labels:
        app: nginx-pod
    spec:
      containers:
      - name: nginx
        image: nginx:1.17.1

使用如下命令创建资源，其中—record参数，用于记录每次的版本变化

[root@master pod_controller]# kubectl apply -f pc_deployment.yaml --record=true
namespace/dev created
deployment.apps/pc-deployment created
[root@master pod_controller]#

通过如下命令可以查看创建结果

[root@master pod_controller]# kubectl get deploy,pod -n dev -o wide
NAME                            READY   UP-TO-DATE   AVAILABLE   AGE    CONTAINERS   IMAGES         SELECTOR
deployment.apps/pc-deployment   3/3     3            3           119s   nginx        nginx:1.17.1   app=nginx-pod
NAME                                 READY   STATUS    RESTARTS   AGE    IP            NODE    NOMINATED NODE   READINESS GATES
pod/pc-deployment-5d9c9b97bb-9rxz6   1/1     Running   0          119s   10.244.1.29   node1   <none>           <none>
pod/pc-deployment-5d9c9b97bb-bg9zn   1/1     Running   0          119s   10.244.1.28   node1   <none>           <none>
pod/pc-deployment-5d9c9b97bb-nfn9f   1/1     Running   0          119s   10.244.2.54   node2   <none>           <none>
[root@master pod_controller]#

如下，可以查看到deployment，ReplicaSet，Pod详细信息

[root@master pod_controller]# kubectl get deploy,rs,pod -n dev -o wide
NAME                            READY   UP-TO-DATE   AVAILABLE   AGE     CONTAINERS   IMAGES         SELECTOR
deployment.apps/pc-deployment   3/3     3            3           3m56s   nginx        nginx:1.17.1   app=nginx-pod
NAME                                       DESIRED   CURRENT   READY   AGE     CONTAINERS   IMAGES         SELECTOR
replicaset.apps/pc-deployment-5d9c9b97bb   3         3         3       3m56s   nginx        nginx:1.17.1   app=nginx-pod,pod-template-hash=5d9c9b97bb
NAME                                 READY   STATUS    RESTARTS   AGE     IP            NODE    NOMINATED NODE   READINESS GATES
pod/pc-deployment-5d9c9b97bb-9rxz6   1/1     Running   0          3m56s   10.244.1.29   node1   <none>           <none>
pod/pc-deployment-5d9c9b97bb-bg9zn   1/1     Running   0          3m56s   10.244.1.28   node1   <none>           <none>
pod/pc-deployment-5d9c9b97bb-nfn9f   1/1     Running   0          3m56s   10.244.2.54   node2   <none>           <none>
[root@master pod_controller]#

三、Deployment控制器实现扩缩容

3.1 通过修改配置文件扩缩容

如下，将pod数量扩容到6个

apiVersion: v1
kind: Namespace
metadata:
  name: dev
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: pc-deployment
  namespace: dev
spec:
  replicas: 6
  selector:
    matchLabels:
      app: nginx-pod
  template:
    metadata:
      labels:
        app: nginx-pod
    spec:
      containers:
      - name: nginx
        image: nginx:1.17.1

然后使用如下命令扩容

[root@master pod_controller]# kubectl apply -f pc_deployment.yaml
namespace/dev configured
deployment.apps/pc-deployment configured
[root@master pod_controller]#

通过如下命令可以查询到此时已经有6个pod在运行了

[root@master pod_controller]# kubectl get deploy,rs,pod -n dev -o wide
NAME                            READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES         SELECTOR
deployment.apps/pc-deployment   6/6     6            6           28m   nginx        nginx:1.17.1   app=nginx-pod
NAME                                       DESIRED   CURRENT   READY   AGE   CONTAINERS   IMAGES         SELECTOR
replicaset.apps/pc-deployment-5d9c9b97bb   6         6         6       28m   nginx        nginx:1.17.1   app=nginx-pod,pod-template-hash=5d9c9b97bb
NAME                                 READY   STATUS    RESTARTS   AGE   IP            NODE    NOMINATED NODE   READINESS GATES
pod/pc-deployment-5d9c9b97bb-2bjlb   1/1     Running   0          30s   10.244.1.30   node1   <none>           <none>
pod/pc-deployment-5d9c9b97bb-4sg8r   1/1     Running   0          30s   10.244.2.56   node2   <none>           <none>
pod/pc-deployment-5d9c9b97bb-9rxz6   1/1     Running   0          28m   10.244.1.29   node1   <none>           <none>
pod/pc-deployment-5d9c9b97bb-bg9zn   1/1     Running   0          28m   10.244.1.28   node1   <none>           <none>
pod/pc-deployment-5d9c9b97bb-nfn9f   1/1     Running   0          28m   10.244.2.54   node2   <none>           <none>
pod/pc-deployment-5d9c9b97bb-vs4zf   1/1     Running   0          30s   10.244.2.55   node2   <none>           <none>
[root@master pod_controller]#

3.2 通过命令进行扩缩容

通过如下命令可以将deployment缩容到3个pod

[root@master pod_controller]# kubectl scale deploy pc-deployment --replicas=3 -n dev
deployment.apps/pc-deployment scaled
[root@master pod_controller]#

如下，可以查询到缩容结果

[root@master pod_controller]# kubectl get deploy,rs,pod -n dev -o wide
NAME                            READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES         SELECTOR
deployment.apps/pc-deployment   3/3     3            3           30m   nginx        nginx:1.17.1   app=nginx-pod
NAME                                       DESIRED   CURRENT   READY   AGE   CONTAINERS   IMAGES         SELECTOR
replicaset.apps/pc-deployment-5d9c9b97bb   3         3         3       30m   nginx        nginx:1.17.1   app=nginx-pod,pod-template-hash=5d9c9b97bb
NAME                                 READY   STATUS    RESTARTS   AGE   IP            NODE    NOMINATED NODE   READINESS GATES
pod/pc-deployment-5d9c9b97bb-9rxz6   1/1     Running   0          30m   10.244.1.29   node1   <none>           <none>
pod/pc-deployment-5d9c9b97bb-bg9zn   1/1     Running   0          30m   10.244.1.28   node1   <none>           <none>
pod/pc-deployment-5d9c9b97bb-nfn9f   1/1     Running   0          30m   10.244.2.54   node2   <none>           <none>
[root@master pod_controller]#

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