K8S - 1.Pod生命周期

Pod生命周期

1.Init C  Pod 第一次创建时 运行  可以N个 并且串行<br />    2.START STOP MainC启动结束是 执行的操作<br />    3.readiness 就绪检测 检测容器是否启动完成 就绪<br />    4.Liveness 当容器不能提供服务时候 就需要Liveness 操作

3.1 Init C
说明：
InitC 也是一个单独的镜像 前一个InitC 成功执行后 才执行下一个
Init容器 会在网络和数据初始化之后启动（Pause）
Pod重启 Init容器必须重新执行
init容器name 不能更Main容器 重复
测试：

apiVersion: v1
kind: Pod
metadata:
  name: myapp-pod
  labels:
    app: myapp
spec:
  containers:
  - name: myapp-container
    image: busybox
    command: ['sh','-c','echo The app is running! && sleep 3600']
  initContainers:
  - name: init-myservice
    image: busybox
    command: ['sh','-c','until nslookup myservice; do echo waiting for myservice; sleep 2;done;']
  - name: init-mydb
    image: busybox
    command: ['sh','-c','until nslookup mydb; do echo waiting for mydb; sleep 2; done;']

kind: Service
apiVersion: v1
metadata:
  name: myservice
spec:
  ports:
    - protocol: TCP
      port: 80
      targetPort: 9376
  ---
kind: Service
apiVersion: v1
metadata:
  name: mydb
spec:
  ports:
    - protocol: TCP
      port: 80
      targetPort: 9377

3.2 探针
探针是由于kubelet对容器执行的定期诊断 kubelet调用由容器实现的Handler 有三种数据处理程序
ExecAction
TCPSocketAction
HTTPGetAction
readinessProbe 就绪探测

apiVersion: v1
kind: Pod
metadata:
  name: readiness-httpget-pod
  namespace: default
spec:
  containers:
  - name: readiness-httpget-container
    image: wangyanglinux/myapp:v1
    imagePullPolicy: IfNotPresent
    readinessProbe:
      httpGet:
        port: 80
        path: /index1.html
        initialDelaySeconds: 1
        periodSeconds: 3

livenessProbe 存活探测

apiVersion: v1
kind: Pod
metadata:
  name: liveness-exec-pod
  namespace: default
spec:
  containers:
  - name: liveness-exec-container
    image: hub.atguigu.com/library/busybox
    imagePullPolicy: IfNotPresent
    command: ["/bin/sh","-c","touch /tmp/live ; sleep 60; rm -rf /tmp/live; sleep3600"]
    livenessProbe:
      exec:
        command: ["test","-e","/tmp/live"]
        initialDelaySeconds: 1
        periodSeconds: 3

HTTP检测

apiVersion: v1
kind: Pod
metadata:
  name: liveness-httpget-pod
  namespace: default
spec:
  ontainers:
  - name: liveness-httpget-container
    image: hub.atguigu.com/library/myapp:v1
    imagePullPolicy: IfNotPresent
    ports:
    - name: http
      containerPort: 80
      livenessProbe:
        httpGet:
          port: http
          path: /index.html
        initialDelaySeconds: 1
        periodSeconds: 3
        timeoutSeconds: 1

TCP检测

apiVersion: v1
kind: Pod
metadata:
  name: probe-tcp
spec:
  containers:
  - name: nginx
    image: hub.atguigu.com/library/myapp:v1
    livenessProbe:
      initialDelaySeconds: 5
      timeoutSeconds: 1
      tcpSocket:
        port: 80

3.3 Start/Stop操作
启动退出操作

apiVersion: v1
kind: Pod
metadata:
  name: lifecycle-demo
spec:
  containers:  
  - name: lifecycle-demo-container
    image: nginx
    lifecycle:
      postStart:
        exec:
          command: ["/bin/sh", "-c", "echo Hello from the postStart handler >/usr/share/message"]
      preStop:
        exec:
          command: ["/bin/sh", "-c", "echo Hello from the poststop handler >/usr/share/message"]

3.4 运行状态
Pending 挂起 Pod已被K8S系统接受 但有一个或者多个容器镜像 未创建 等待时间包括调度Pod的时间和网络下载镜像时间
Running 运行 Pod已经绑定到一个节点上 Pod中所有容器已经被创建 至少一个容器在运行 或者处于启动或重启状态(不可用)
Succeeded 成功 Pod中所有容器都被成功终止 不会再重启
Failed 失败 Pod中所有容器都已经终止 且至少有一个容器因为失败而终止 容器非0状态退出
Unknow 未知