Kubernetes进阶实战读书笔记：Deployment控制器

一、Deployment控制器

deployment控制器资源的主要职责同样是为了保证POD资源的健康运行、其大部分功能均可通过调用replicaset控制器来实现
同时还增添了部分特性：

1、事件和状态查看：必要时可以查看Deployment对象升级的详细进度和状态
2、回滚：升级操作完成后发现问题时、支持使用回滚机制将应用返回到前一个或由用户指定的历史记录中的版本上
3、版本记录：对Deployment对象的每一次操作都予以保存、以供后续可能执行的回滚操作使用
4、暂停和启动：对于每一次升级、都能够随时暂停和启动
5、多种自动更新方案：一个Recreate、即重建更新机制、全面停止、删除旧有的POD后用新版本替代；另一个RollingUpdate
即滚动升级机制、逐步替换旧有的pod至新的版本

二、 创建deployment

1、资源清单

[root@master chapter5]# cat myapp-deploy.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-deploy
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: myapp
        image: ikubernetes/myapp:v1
        ports:
        - containerPort: 80
          name: http

2、创建运行

[root@master chapter5]# kubectl apply -f myapp-deploy.yaml --record
deployment.apps/myapp-deploy created

3、验证效果

[root@master chapter5]# kubectl apply -f myapp-deploy.yaml --record
deployment.apps/myapp-deploy created
[root@master chapter5]# kubectl get ds myapp-deploy
Error from server (NotFound): daemonsets.apps "myapp-deploy" not found
[root@master chapter5]# kubectl get deployments myapp-deploy
NAME READY UP-TO-DATE AVAILABLE AGE
myapp-deploy 3/3 3 3 27s

三、更新策略

 1、查看详细更新事件

[root@master chapter5]# kubectl describe deployments myapp-deploy 
Name:                   myapp-deploy
Namespace:              default
CreationTimestamp:      Fri, 12 Jun 2020 11:55:09 +0800
Labels:                 
Annotations:            deployment.kubernetes.io/revision: 1
                        kubernetes.io/change-cause: kubectl apply --filename=myapp-deploy.yaml --record=true
Selector:               app=myapp
Replicas:               3 desired | 3 updated | 3 total | 3 available | 0 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:  app=myapp
  Containers:
   myapp:
    Image:        ikubernetes/myapp:v1
    Port:         80/TCP
    Host Port:    0/TCP
    Environment:  
    Mounts:       
  Volumes:        
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      True    MinimumReplicasAvailable
  Progressing    True    NewReplicaSetAvailable
OldReplicaSets:  
NewReplicaSet:   myapp-deploy-5cbd66595b (3/3 replicas created)
Events:
  Type    Reason             Age    From                   Message
  ----    ------             ----   ----                   -------
  Normal  ScalingReplicaSet  3m23s  deployment-controller  Scaled up replica set myapp-deploy-5cbd66595b to 3　　

2、滚动更新图解

 

 3、更新字段详解

[root@master ~]# kubectl explain  deploy.spec.strategy.rollingUpdate
KIND:     Deployment
VERSION:  apps/v1

RESOURCE: rollingUpdate