kubernetes探针

LivenessProbe：周期性检测，检测未通过时，kubelet会根据restartPolicy的定义来决定是否会重启该容器；未定义时，kubelet认为容器未终止，即为健康；

ReadnessProbe：周期性检测，检测未通过时，与该Pod关联的Service，会将该Pod从Service的后段可用端点列表中删除；直到再次就绪再重新添加回来，未定义时，只要容器未终止，即为就绪；

StartupProbe：便于用户使用同livenessProbe不同参数或阈值；

 

三种探针：

  ExecAction：直接执行命令，命令成功返回表示探测成功；

  TCPSocketAction：端口正常打开，即成功；

  HTTPGetAction：向指定的path发送HTTP请求，2xx，3xx的响应码表示成功；

 

命令探测

[root@master probe]# kubectl apply -f liveness-exec-demo.yaml 
[root@master probe]# cat liveness-exec-demo.yaml 
apiVersion: v1
kind: Pod
metadata:
  name: liveness-exec-demo
  namespace: default
spec:
  containers:
  - name: demo
    image: ikubernetes/demoapp:v1.0
    imagePullPolicy: IfNotPresent
    livenessProbe:
      exec:
        command: ['/bin/sh', '-c', '[ "$(curl -s 127.0.0.1/livez)" == "OK" ]']
      initialDelaySeconds: 5  #5秒后探测
      timeoutSeconds: 1       #延迟时间1秒
      periodSeconds: 5        #间隔时间5秒

进入到Pod将livez改成FAIL，容器会自动重启

[root@master probe]# kubectl  exec -it liveness-exec-demo  /bin/sh
kubectl exec [POD] [COMMAND] is DEPRECATED and will be removed in a future version. Use kubectl exec [POD] -- [COMMAND] instead.

[root@liveness-exec-demo /]# curl 10.244.166.154/livez
OK
[root@liveness-exec-demo /]# curl -XPOST -d 'livez=FAIL' 10.244.166.154/livez
[root@liveness-exec-demo /]# curl 10.244.166.154/livez

TCP探测

[root@master probe]# kubectl apply -f  liveness-tcpsocket-demo.yaml 
[root@master probe]# cat liveness-tcpsocket-demo.yaml 
apiVersion: v1
kind: Pod
metadata:
  name: liveness-tcpsocket-demo
  namespace: default
spec:
  containers:
  - name: demo
    image: ikubernetes/demoapp:v1.0
    imagePullPolicy: IfNotPresent
    ports:
    - name: http
      containerPort: 80
    securityContext:
      capabilities:
        add:
        - NET_ADMIN
    livenessProbe:
      tcpSocket:
        port: http
      periodSeconds: 5
      initialDelaySeconds: 5

[root@master probe]# kubectl get pods
NAME                      READY   STATUS    RESTARTS       AGE
liveness-exec-demo        1/1     Running   1 (143m ago)   62m
liveness-tcpsocket-demo   1/1     Running   0              3s

 在容器内把80端口拒绝掉就会探测失败

[root@master probe]# kubectl exec liveness-tcpsocket-demo  -- iptables -A INPUT -p tcp --dport 80 -j REJECT

http探测

[root@master probe]# kubectl apply -f liveness-httpget-demo.yaml 
[root@master probe]# cat liveness-httpget-demo.yaml 
apiVersion: v1
kind: Pod
metadata:
  name: liveness-httpget-demo
  namespace: default
spec:
  containers:
  - name: demo
    image: ikubernetes/demoapp:v1.0
    imagePullPolicy: IfNotPresent
    livenessProbe:
      httpGet:
        path: '/livez'
        port: 80
        scheme: HTTP
      initialDelaySeconds: 5

[root@master probe]# kubectl get pods
NAME                      READY   STATUS             RESTARTS       AGE
liveness-exec-demo        1/1     Running            1 (152m ago)   71m
liveness-httpget-demo     1/1     Running            0              3m42s
liveness-tcpsocket-demo   0/1     CrashLoopBackOff   6 (57s ago)    8m33s
[root@master probe]# kubectl  exec -it liveness-httpget-demo -- /bin/sh
[root@liveness-httpget-demo /]# 
[root@liveness-httpget-demo /]# curl 127.0.0.1/livez
OK[root@liveness-httpget-demo /]# 
[root@liveness-httpget-demo /]# curl -XPOST -d 'livez=FAIL' 127.0.0.1/livez
[root@liveness-httpget-demo /]# curl -I 127.0.0.1/livez
HTTP/1.0 506 VARIANT ALSO NEGOTIATES
Content-Type: text/html; charset=utf-8
Content-Length: 4
Server: Werkzeug/1.0.0 Python/3.8.2
Date: Thu, 09 Feb 2023 09:07:16 GMT

 

 

Readnessprobe http探针

[root@master probe]# kubectl apply -f readiness-httpget-demo.yaml 
[root@master probe]# cat readiness-httpget-demo.yaml 
apiVersion: v1
kind: Pod
metadata:
  name: readiness-httpget-demo
  namespace: default
spec:
  containers:
  - name: demo
    image: ikubernetes/demoapp:v1.0
    imagePullPolicy: IfNotPresent
    readinessProbe:
      httpGet:
        path: 'readyz'
        port: 80
        scheme: HTTP
      initialDelaySeconds: 15
      timeoutSeconds: 2
      periodSeconds: 5
      failureThreshold: 3
  restartPolicy: Always

[root@readiness-httpget-demo /]# curl http://10.244.166.155:80/readyz
OK
[root@readiness-httpget-demo /]# curl -XPOST -d 'readyz=FAIL' 10.244.166.155:80/readyz
[root@readiness-httpget-demo /]# curl -I 10.244.166.155:80/readyz
HTTP/1.0 507 INSUFFICIENT STORAGE
Content-Type: text/html; charset=utf-8
Content-Length: 4
Server: Werkzeug/1.0.0 Python/3.8.2
Date: Thu, 09 Feb 2023 07:35:16 GMT