[teacher Zhao Yuqiang] kubernetes' probe

Kubernetes Probes are provided （Probe） Check the health of the container . In fact, we don't just need to do health testing on containers , Also, health testing should be carried out for the application arranged in the container .

Probe There are two types ：

• livenessProbe： Survival probe , If the check fails , Will kill the container , according to Pod Of restartPolicy Restart policy operations .
• readinessProbe： Ready probe , If the check fails ,Kubernetes Will be able to Pod from service endpoints Middle elimination .

Probe The following three inspection methods are supported ：

• httpGet： send out HTTP request , return 200-400 Range status code is success .
• exec： perform Shell The command return status code is 0 For success .
• tcpSocket： launch TCP Socket Build success .

Let's show the configuration of each checking method ：

• exec Check

apiVersion: v1
kind: Pod
metadata:
  labels:
    test: liveness
  name: liveness-exec
spec:
  containers:
  - name: liveness
    image: busybox
    args:
    - /bin/sh
    - -c
    - touch /tmp/healthy; sleep 30; rm -rf /tmp/healthy; sleep 600
    livenessProbe:  ##  livenessProbe Check the type 
      exec:    ##exec Check the method 
        command:
        - cat
        - /tmp/healthy
      initialDelaySeconds: 5   ## Container start up 5 I don't want to check until a few seconds later 
      periodSeconds: 5    ##  every other 5 Check every second 

• httpGet Check

apiVersion: v1
kind: Pod
metadata:
  labels:
    test: liveness
  name: liveness-http
spec:
  containers:
  - name: liveness
    image: k8s.gcr.io/liveness
    args:
    - /server
    livenessProbe:   ## livenessProbe type 
      httpGet:   ## httpGet Check the method 
        path: /healthz
        port: 8080
        httpHeaders:
        - name: Custom-Header
          value: Awesome
      initialDelaySeconds: 3
      periodSeconds: 3

• tcpSocket Check

apiVersion: v1
kind: Pod
metadata:
  name: goproxy
  labels:
    app: goproxy
spec:
  containers:
  - name: goproxy
    image: k8s.gcr.io/goproxy:0.1
    ports:
    - containerPort: 8080
    readinessProbe:   ##readinessProbe Check the type 
      tcpSocket:  ##tcpSocket Check the method 
        port: 8080
      initialDelaySeconds: 5
      periodSeconds: 10
    livenessProbe:   ##livenessProbe Check the type 
      tcpSocket:   ##tcpSocket Check the method 
        port: 8080
      initialDelaySeconds: 15
      periodSeconds: 20