5.kubelet探针

探针是由kubelet对容器定期的诊断，探测有三种类型

.执行自定义命令            execAction 在容器内执行命令，返回码为0表示成功，返回为其它表示失败
.向指定的tcp套节字发请求   TCPsocketAction 对指定的端口发起请求
.向指定的http服务发请求    HttpGetAction 返回状态码大于等于200，且小于400表示成功

2.5.3.1容器的就绪性探测，就是容器能对外提供服务后，才可以被service关联到后端

readiness-httpget方法模板

vim readiness-httpget.yaml
apiVersion: v1
kind: Pod
metadata:
  name: readiness-httpget-pod
spec:
  containers:
  - name: readiness-httpget-pod
    image: ikubernetes/myapp:v1
    imagePullPolicy: IfNotPresent
    ports:
    - name: http
      containerPort: 80
    readinessProbe:
      httpGet:
        port: http
        path: /oldboy.html
      initialDelaySeconds: 1
      failureThreshold: 3
  restartPolicy: Always

2.5.3.2 存活性检查，每隔多长时间检查一次，这个动作持续到容器退出为止

liveness-exec方法探测

vim liveness-exec.yaml
apiVersion: v1
kind: Pod
metadata:
  name: liveness-exec-pod
  namespace: default
spec:
  containers:
  - name: liveness-exec-pod
    image: busybox:latest
    imagePullPolicy: IfNotPresent
    command: ["/bin/sh","-c","touch /tmp/healthy; sleep 30; rm /tmp/healthy; sheep 300"]
    livenessProbe:
      exec:
       command: ["test","-e","/tmp/healthy"]#检查此文件是否存在
      initialDelaySeconds: 1
      periodSeconds: 3
  restartPolicy: Always

liveness-httpget方法探测

apiVersion: v1
kind: Pod
metadata:
  name: liveness-httpget-pod
  namespace: default
spec:
  containers:
  - name: liveness-httpget-pod
    image: ikubernetes/myapp:v1
    imagePullPolicy: IfNotPresent
    ports:
    - name: http
      containerPort: 80
    livenessProbe:
      httpGet:
        port: http
        path: /index.html
      initialDelaySeconds: 1
      periodSeconds: 3
  restartPolicy: Always

liveness-tcpsocket方法探测

vim liveness-tcpsocket.yaml
apiVersion: v1
kind: Pod
metadata:
  name: liveness-tcpsocket-pod
  namespace: default
spec:
  containers:
  - name: liveness-tcpsocket-pod
    image: nginx:1.14-alpine
    imagePullPolicy: IfNotPresent
    ports:
      - containerPort: 80
    livenessProbe:
      tcpSocket:
        port: 80
      initialDelaySeconds: 1
      periodSeconds: 3
  restartPolicy: Always