组成结构

一个 Deployment 拥有多个 Replica Set，而一个 Replica Set 拥有一个或多个 Pod

一个 Deployment 控制多个 rs 主要是为了支持回滚机制，每当 Deployment 操作时，Kubernetes会重新生成一个 Replica Set 并保留，以后有需要的话就可以回滚至之前的状态

deploy.spec

标签选择 selector

spec:
selector:
matchLabels:
xx: yy

pod 副本数 replicas

spec:
replicas: 1

滚动更新 strategy

spec:
minReadySeconds: 10
revisionHistoryLimit：5
pause: false
strategy:
type: RollingUpdate
rollingUpdate:
maxSurge: 1
maxUnavailable: 1

minReadySeconds
滚动更新中新建 pod 起来后多久杀死旧 pod
默认0 ，新容器启动起来后就杀掉旧pod

revisionHistoryLimit
限制最大保留的 revision number
默认 10

pause
进行更新是否停止

type
Recreate 全部重新创建
RollingUpdate 默认

rollingUpdate
上面指定 type: RollingUpdate 才生效

maxSurge
升级过程中最多新建的 pod 数量
例：maxSurage=1，replicas=5,则表示Kubernetes会先启动1一个新的Pod后才删掉一个旧的POD，整个升级过程中最多会有5+1个POD
如果 maxUnavailable为0 ，maxSurge不能为0

maxUnavailable
升级过程中最多杀死的旧 pod 数量
如果 maxSurge 为 0 ，maxUnavailable 不能为0
例：maxUnavaible=1，则表示Kubernetes整个升级过程中最多会有1个POD处于无法服务的状态

hpa HorizontalPodAutoscaler

metrics-server-v0.4.2

apiVersion: v1
kind: ServiceAccount
metadata:
  labels:
    k8s-app: metrics-server
  name: metrics-server
  namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  labels:
    k8s-app: metrics-server
    rbac.authorization.k8s.io/aggregate-to-admin: "true"
    rbac.authorization.k8s.io/aggregate-to-edit: "true"
    rbac.authorization.k8s.io/aggregate-to-view: "true"
  name: system:aggregated-metrics-reader
rules:
- apiGroups:
  - metrics.k8s.io
  resources:
  - pods
  - nodes
  verbs:
  - get
  - list
  - watch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  labels:
    k8s-app: metrics-server
  name: system:metrics-server
rules:
- apiGroups:
  - ""
  resources:
  - pods
  - nodes
  - nodes/stats
  - namespaces
  - configmaps
  verbs:
  - get
  - list
  - watch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  labels:
    k8s-app: metrics-server
  name: metrics-server-auth-reader
  namespace: kube-system
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: extension-apiserver-authentication-reader
subjects:
- kind: ServiceAccount
  name: metrics-server
  namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  labels:
    k8s-app: metrics-server
  name: metrics-server:system:auth-delegator
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: system:auth-delegator
subjects:
- kind: ServiceAccount
  name: metrics-server
  namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  labels:
    k8s-app: metrics-server
  name: system:metrics-server
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: system:metrics-server
subjects:
- kind: ServiceAccount
  name: metrics-server
  namespace: kube-system
---
apiVersion: v1
kind: Service
metadata:
  labels:
    k8s-app: metrics-server
  name: metrics-server
  namespace: kube-system
spec:
  ports:
  - name: https
    port: 443
    protocol: TCP
    targetPort: https
  selector:
    k8s-app: metrics-server
---
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    k8s-app: metrics-server
  name: metrics-server
  namespace: kube-system
spec:
  selector:
    matchLabels:
      k8s-app: metrics-server
  strategy:
    rollingUpdate:
      maxUnavailable: 0
  template:
    metadata:
      labels:
        k8s-app: metrics-server
    spec:
      containers:
      - args:
        - --cert-dir=/tmp
        - --kubelet-insecure-tls
        - --secure-port=4443
        - --kubelet-preferred-address-types=InternalIP,ExternalIP,Hostname
        - --kubelet-use-node-status-port
        image: k8s.gcr.io/metrics-server/metrics-server:v0.4.2
        imagePullPolicy: IfNotPresent
        livenessProbe:
          failureThreshold: 3
          httpGet:
            path: /livez
            port: https
            scheme: HTTPS
          periodSeconds: 10
        name: metrics-server
        ports:
        - containerPort: 4443
          name: https
          protocol: TCP
        readinessProbe:
          failureThreshold: 3
          httpGet:
            path: /readyz
            port: https
            scheme: HTTPS
          periodSeconds: 10
        securityContext:
          readOnlyRootFilesystem: true
          runAsNonRoot: true
          runAsUser: 1000
        volumeMounts:
        - mountPath: /tmp
          name: tmp-dir
      nodeSelector:
        kubernetes.io/os: linux
      priorityClassName: system-cluster-critical
      serviceAccountName: metrics-server
      volumes:
      - emptyDir: {}
        name: tmp-dir
---
apiVersion: apiregistration.k8s.io/v1
kind: APIService
metadata:
  labels:
    k8s-app: metrics-server
  name: v1beta1.metrics.k8s.io
spec:
  group: metrics.k8s.io
  groupPriorityMinimum: 100
  insecureSkipTLSVerify: true
  service:
    name: metrics-server
    namespace: kube-system
  version: v1beta1
  versionPriority: 100

示例


apiVersion: apps/v1
kind: Deployment
metadata:
  name: c7-dep
  namespace: default
spec:
  selector:
    matchLabels:
      app: c7-dep
  replicas: 3
  strategy:
    type: RollingUpdate
  template:
    metadata:
      labels:
        app: c7-dep
    spec:
      containers:
      - image: centos:7.4
        name: c7-dep-centos7
        command: 
        - /bin/sh
        - -c 
        - sleep 6000
        resources:
          limits:
            cpu: 1200m
          requests:
            cpu: 1000m

apiVersion: autoscaling/v1
kind: HorizontalPodAutoscaler
metadata:
  name: c7-hpa
spec:
  maxReplicas: 40
  minReplicas: 2
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: c7-dep
  targetCPUUtilizationPercentage: 70

示例实践结论

deploy 必须指定资源限制，requests.cpu 优先，不设置按 limits.cpu
按 cpu 以总量的百分比

kube-controller-manager 参数

—horizontal-pod-autoscaler-sync-period
HPA Controller 默认 30s 轮询一次，查询指定的资源（RC或者Deployment）中Pod的资源使用率，并且与创建时设定的值和指标做对比，从而实现自动伸缩的功能

—horizontal-pod-autoscaler-downscale-stabilization
设置一个持续时间，用于指定在当前操作完成后，HPA 必须等待多长时间才能执行另一次缩放操作。默认为5分钟，也就是默认需要等待5分钟后才会开始自动缩放

deployment(deploy)