探针类型、方式及实验

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目录

1、tcpSocket方式

 2、就绪检测

 3、就绪检测2

4、启动、退出动作

5、探针

5.1探针的三种类型

5.2探针的三种方式

1、tcpSocket方式

vim tcpsocket.yaml apiVersion: v1 kind: Pod metadata: name: probe-tcp spec: containers: - name: nginx image: soscscs/myapp:v1 livenessProbe: initialDelaySeconds: 5 timeoutSeconds: 1 tcpSocket: port: 8080 periodSeconds: 10 failureThreshold: 2 kubectl create -f tcpsocket.yaml kubectl exec -it probe-tcp -- netstat -natp kubectl get pods -w

 2、就绪检测

vim readiness-httpget.yaml
apiVersion: v1
kind: Pod
metadata:
  name: readiness-httpget
  namespace: default
spec:
  containers:
  - name: readiness-httpget-container
    image: soscscs/myapp:v1
    imagePullPolicy: IfNotPresent
    ports:
    - name: http
      containerPort: 80
    readinessProbe:
      httpGet:
        port: 80
        path: /index1.html
      initialDelaySeconds: 1
      periodSeconds: 3
    livenessProbe:
      httpGet:
        port: http
        path: /index.html
      initialDelaySeconds: 1
      periodSeconds: 3
      timeoutSeconds: 10

kubectl create -f readiness-httpget.yaml

kubectl get pods 

kubectl exec -it readiness-httpget sh
 # cd /usr/share/nginx/html/
 # ls
50x.html    index.html
 # echo 123 > index1.html 
 # exit

kubectl get pods 

kubectl exec -it readiness-httpget -- rm -rf /usr/share/nginx/html/index.html

kubectl get pods -w

 3、就绪检测2

vim readiness-myapp.yaml
apiVersion: v1
kind: Pod
metadata:
  name: myapp1
  labels:
     app: myapp
spec:
  containers:
  - name: myapp
    image: soscscs/myapp:v1
    ports:
    - name: http
      containerPort: 80
    readinessProbe:
      httpGet:
        port: 80
        path: /index.html
      initialDelaySeconds: 5
      periodSeconds: 5
      timeoutSeconds: 10 
---
apiVersion: v1
kind: Pod
metadata:
  name: myapp2
  labels:
     app: myapp
spec:
  containers:
  - name: myapp
    image: soscscs/myapp:v1
    ports:
    - name: http
      containerPort: 80
    readinessProbe:
      httpGet:
        port: 80
        path: /index.html
      initialDelaySeconds: 5
      periodSeconds: 5
      timeoutSeconds: 10 
---
apiVersion: v1
kind: Pod
metadata:
  name: myapp3
  labels:
     app: myapp
spec:
  containers:
  - name: myapp
    image: soscscs/myapp:v1
    ports:
    - name: http
      containerPort: 80
    readinessProbe:
      httpGet:
        port: 80
        path: /index.html
      initialDelaySeconds: 5
      periodSeconds: 5
      timeoutSeconds: 10 
---
apiVersion: v1
kind: Service
metadata:
  name: myapp
spec:
  selector:
    app: myapp
  type: ClusterIP
  ports:
  - name: http
    port: 80
    targetPort: 80

kubectl create -f readiness-myapp.yaml

kubectl get pods,svc,endpoints -o wide

kubectl exec -it pod/myapp1 -- rm -rf /usr/share/nginx/html/index.html

kubectl get pods,svc,endpoints -o wide

4、启动、退出动作

vim post.yaml apiVersion: v1 kind: Pod metadata: name: lifecycle-demo spec: containers: - name: lifecycle-demo-container image: soscscs/myapp:v1 lifecycle: #此为关键字段 postStart: exec: command: ["/bin/sh", "-c", "echo Hello from the postStart handler >> /var/log/nginx/message"] preStop: exec: command: ["/bin/sh", "-c", "echo Hello from the poststop handler >> /var/log/nginx/message"] volumeMounts: - name: message-log mountPath: /var/log/nginx/ readOnly: false initContainers: - name: init-myservice image: soscscs/myapp:v1 command: ["/bin/sh", "-c", "echo 'Hello initContainers' >> /var/log/nginx/message"] volumeMounts: - name: message-log mountPath: /var/log/nginx/ readOnly: false volumes: - name: message-log hostPath: path: /data/volumes/nginx/log/ type: DirectoryOrCreate 

kubectl create -f post.yaml kubectl get pods -o wide kubectl exec -it lifecycle-demo -- cat /var/log/nginx/message //在 node02 节点上查看 cd /data/volumes/nginx/log/ ls cat message //删除 pod 后，再在 node02 节点上查看(在master节点删除） kubectl delete pod lifecycle-demo cat message

5、探针

健康检查：又称为探针，探针是由kubelet对容器执行的定期诊断。

5.1探针的三种类型

（1）存储探针（livenessProbe):判断容器是否运行正常，如果探测失败则杀掉容器（不是pod)，容器会根据容器策略决定是否重启
（2）就绪探针（readinesspProbe):判断pod是否能够进入ready状态，做好接受请求的准备，探测失败会进入notreadyp状态并且从service资源的endpoints中剔除，service 将不会在把访问请求转发给这个pod
（3）启动探针(starupProbe):判断容器内的应用是否启动成功，在探测成功状态sucess之前，其他探针都会处于失效状态
 

5.2探针的三种方式

（1）exec ：在容器内执行指定命令。如果命令退出时返回码为0则认为诊断成功。

（2）tcpSocket ：对指定端口上的容器的IP地址进行TCP检查（三次握手）。如果端口打开，则诊断被认为是成功的。

（3）httpGet ：对指定的端口和路径上的容器的IP地址执行HTTPGet请求。如果响应的状态码大于等于200且小于400，则诊断被认为是成功的。