k8s学习笔记-P21-探针-实操

教程：尚硅谷Kubernetes教程(K8s入门到精通)_哔哩哔哩_bilibili

笔记摘自视频章节：第四章-p22

主题

测试k8s中的探针： readiness和liveness

操作

就绪检测 readiness

• 创建一个带就绪探针的pod yaml文件

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

• 字段讲解

  • imagePullPolicy: 镜像下载策略
  • readinessProbe: 就绪检测方案
    • httpGet: 检查http
    • inititalDelaySeconds: 延时策略
    • periodSeconds: 周期执行时间

• 查看pod 状态，一直未就绪

kubectl get pod
NAME                               READY   STATUS      RESTARTS       AGE
readiness-httpget-pod    0/1     Running         0                    12s

• 分析原因: 确认为404，所以一直在未就绪状态

kubectl describd pods readiness-httpget-pod
Events:
  Type     Reason     Age                    From               Message
  ----     ------     ----                   ----               -------
  Normal   Scheduled  14m                    default-scheduler  Successfully assigned default/readiness-httpget-pod to jjh-k8s-demo-node1
  Normal   Pulling    14m                    kubelet            Pulling image "wangyanglinux/myapp:v1"
  Normal   Pulled     14m                    kubelet            Successfully pulled image "wangyanglinux/myapp:v1" in 12.760578508s
  Normal   Created    14m                    kubelet            Created container readiness-httpget-container
  Normal   Started    14m                    kubelet            Started container readiness-httpget-container
  Warning  Unhealthy  4m15s (x205 over 14m)  kubelet            Readiness probe failed: HTTP probe failed with statuscode: 404

• 尝试恢复，使得改html存在，httpGet条件满足后，期望pod的readiness检查通过。
  • sh进入pod：kubectl exec readiness-httpget-pod -it -- /bin/sh
  • 创建文件： echo "123" >> /usr/share/nginx/html/index1.html
  • 退出
  • 查看pod状态，已经恢复正常

存活检测 liveness

case1: 文件检查

• 创建yaml，就绪条件为：检查文件/tmp/live存在

apiVersion: v1
kind: Pod
metadata:
  name: liveness-exec-pod
  namespace: default
spec:
  containers:
    - name: liveness-exec-container
      image: busybox
      imagePullPolicy: IfNotPresent
      command: ["/bin/sh","-c", "touch /tmp/live ; sleep 60; rm -rf /tmp/live; sleep 3600"]
      livenessProbe:
        exec:
          command: ["test","-e","/tmp/live"]
        initialDelaySeconds: 1
        periodSeconds: 3

• 创建pod：

  kubectl create -f p21_liveness_probe.yaml
  pod/liveness-exec-pod created
  

• 状态跟踪

  • 一开始一直是运行着的

  kubectl get pods
  NAME                READY   STATUS    RESTARTS   AGE
  liveness-exec-pod   1/1     Running   0          8s
  

  • 监测，等待一分钟，发现pod在一分钟后重启，探活机制成功触发

  kubectl get pods -w
  NAME                READY   STATUS    RESTARTS   AGE
  liveness-exec-pod   1/1     Running   0          36s
  liveness-exec-pod   1/1     Running   1 (1s ago)   100s
  

case2: tcpSocket

• 文件

apiVersion: v1
kind: Pod
metadata:
  name: probe-tcp
spec:
  containers:
  - name: nginx
    image: wangyanglinux/myapp:v1
    imagePullPolicy: IfNotPresent
    livenessProbe:
      initialDelaySeconds: 5
      timeoutSeconds: 1
      tcpSocket:
        port: 21212

• 查看发现不断重启，这是因为21212单口一直没有就绪

kubectl get pod -o wide -w
NAME        READY   STATUS    RESTARTS   AGE   IP            NODE                 NOMINATED NODE   READINESS GATES
probe-tcp   1/1     Running   0          4s    10.244.1.17   jjh-k8s-demo-node1   <none>           <none>
probe-tcp   1/1     Running   1 (1s ago)   31s   10.244.1.17   jjh-k8s-demo-node1   <none>           <none>
probe-tcp   1/1     Running   2 (1s ago)   61s   10.244.1.17   jjh-k8s-demo-node1   <none>           <none>
probe-tcp   1/1     Running   3 (1s ago)   91s   10.244.1.17   jjh-k8s-demo-node1   <none>           <none>

其他

还有readiness和liveness组合使用的case，不作赘述