创建Deployment

nginx-deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  progressDeadlineSeconds: 600
  replicas: 10
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      app: nginx-deployment
  strategy:
rollingUpdate:
      # 升级过程中最多比replicas多出的新增Pod数量
      maxSurge: 25%
      # 升级过程中最多的无法提供服务的Pod数量
      maxUnavailable: 25%
    type: RollingUpdate
  template:
    metadata:
      labels:
        app: nginx-deployment
    spec:
      containers:
      - name: nginx-deployment
        image: nginx:1.9
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 80

创建应用

kubectl create -f nginx-deployment.yaml

更新镜像

kubectl set image nginx-deployment nginx-deployment=nginx:1.9.3

滚动更新过程

创建newRS，replicas 是3。

// 10*25%=2.5
// 向上取整为3
maxSurge = replicas * deployment.spec.strategy.rollingUpdate.maxSurge

缩容oldRS，replicas是8。

// 10*0.25=2.5
// 向下取整为2
maxUnavailable = replicas * deployment.spec.strategy.rollingUpdate.maxUnavailable

newRS不断增加到10个，oldRS不断减少到0个。变化过程中，Pod总数控制在13个，最少的可提供服务数量控制在8个。

// 8 = 10 - 2
minAvailable := *(deployment.Spec.Replicas) - maxUnavailable