关于Kubernetes-v1.23.6-readinessProbe-就绪探针的效果演示及说明

1、本文还是先创建一个带有 readinessProbe-就绪探针 的yaml 文件， nginx-demo.yaml，内容如下：

apiVersion: v1      # api 文档版本
kind: Pod           # 资源对象类型，也可以配置为像Deployment、StatefulSet这一类的对象
metadata:           # Pod 相关的元数据，用于描述 Pod 的数据
  name: nginx-demo  # Pod 的名称
  namespace: 'default' # 命名空间的配置
spec:                  # 期望 Pod 按照这里面的描述进行创建
  containers:          # 对于 Pod 中的容器描述
  - name: nginx        # 容器的名称
    image: nginx:1.7.9 # 指定容器的镜像
    imagePullPolicy: IfNotPresent # 镜像拉取策略，指定如果本地有就用本地的，如果没有就拉取远程的

    startupProbe:   # 应用启动探针配置
      exec:
        command:
        - sh
        - -c
        - "sleep 1;echo success > /inited"

      failureThreshold: 3   # 失败多少次才算真正失败
      periodSeconds: 10     # 间隔时间
      successThreshold: 1   # 多少次监测成功才算真正的成功
      timeoutSeconds: 5     # 请求的超时时间

    readinessProbe:   # 应用就绪探针配置
      httpGet:
        path: /started.html
        port: 80

      failureThreshold: 5   # 失败多少次才算真正失败
      periodSeconds: 10     # 间隔时间
      successThreshold: 1   # 多少次监测成功才算真正的成功
      timeoutSeconds: 3     # 请求的超时时间

    ports:
    - name: http        # 端口名称
      containerPort: 80 # 描述容器内要暴露什么端口
      protocol: TCP     # 描述该端口是基于哪种协议通信的

  restartPolicy: OnFailure # 重启策略，只有失败的情况才会重启

2、然后再创建pod，使用 kubectl create -f nginx-demo.yaml 命令进行pod的创建

3、接下来我们观察状态的变化，pod的状态，始终没有READY ，一直是0/1

[root@k8s-master ~]# kubectl get po
NAME         READY   STATUS    RESTARTS   AGE
nginx-demo   0/1     Running   0          25s
NAME         READY   STATUS    RESTARTS   AGE
nginx-demo   0/1     Running   0          53s
[root@k8s-master ~]# kubectl describe pod nginx-demo
......................省略部分..............................
Events:
  Type     Reason     Age               From               Message
  ----     ------     ----              ----               -------
  Normal   Scheduled  55s               default-scheduler  Successfully assigned default/nginx-demo to k8s-node2
  Normal   Pulled     54s               kubelet            Container image "nginx:1.7.9" already present on machine
  Normal   Created    54s               kubelet            Created container nginx
  Normal   Started    53s               kubelet            Started container nginx
  Warning  Unhealthy  5s (x5 over 44s)  kubelet            Readiness probe failed: HTTP probe failed with statuscode: 404
[root@k8s-master ~]# 
[root@k8s-master ~]# kubectl get po
NAME         READY   STATUS    RESTARTS   AGE
nginx-demo   0/1     Running   0          8m59s
[root@k8s-master ~]# kubectl get po
NAME         READY   STATUS    RESTARTS   AGE
nginx-demo   0/1     Running   0          9m
[root@k8s-master ~]# kubectl describe pod nginx-demo
Name:         nginx-demo
Namespace:    default
Priority:     0
Node:         k8s-node2/192.168.113.122
Start Time:   Thu, 07 Sep 2023 22:55:23 +0800
Labels:       <none>
Annotations:  cni.projectcalico.org/containerID: b2a16d93bb97564900351dc36dbdc1b0714fa4d344bf8d0ec6361c647311d63e
              cni.projectcalico.org/podIP: 10.224.169.135/32
              cni.projectcalico.org/podIPs: 10.224.169.135/32
Status:       Running
IP:           10.224.169.135
IPs:
  IP:  10.224.169.135
Containers:
  nginx:
    Container ID:   docker://45572be22ee60b8f62143a3890308775562cede4c2c1828128dbbd693f8f9459
    Image:          nginx:1.7.9
    Image ID:       docker-pullable://nginx@sha256:e3456c851a152494c3e4ff5fcc26f240206abac0c9d794affb40e0714846c451
    Port:           80/TCP
    Host Port:      0/TCP
    State:          Running
      Started:      Thu, 07 Sep 2023 22:55:25 +0800
    Ready:          False
    Restart Count:  0
    Readiness:      http-get http://:80/started.html delay=0s timeout=3s period=10s #success=1 #failure=5
    Startup:        exec [sh -c sleep 1;echo success > /inited] delay=0s timeout=5s period=10s #success=1 #failure=3
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-jq6wz (ro)
Conditions:
  Type              Status
  Initialized       True
  Ready             False
  ContainersReady   False
  PodScheduled      True
Volumes:
  kube-api-access-jq6wz:
    Type:                    Projected (a volume that contains injected data from multiple sources)
    TokenExpirationSeconds:  3607
    ConfigMapName:           kube-root-ca.crt
    ConfigMapOptional:       <nil>
    DownwardAPI:             true
QoS Class:                   BestEffort
Node-Selectors:              <none>
Tolerations:                 node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
                             node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
  Type     Reason     Age                     From               Message
  ----     ------     ----                    ----               -------
  Normal   Scheduled  9m2s                    default-scheduler  Successfully assigned default/nginx-demo to k8s-node2
  Normal   Pulled     9m1s                    kubelet            Container image "nginx:1.7.9" already present on machine
  Normal   Created    9m1s                    kubelet            Created container nginx
  Normal   Started    9m                      kubelet            Started container nginx
  Warning  Unhealthy  3m52s (x34 over 8m51s)  kubelet            Readiness probe failed: HTTP probe failed with statuscode: 404
[root@k8s-master ~]# 
[root@k8s-master ~]# kubectl get po
NAME         READY   STATUS    RESTARTS   AGE
nginx-demo   0/1     Running   0          9m7s
[root@k8s-master ~]#

4、此时，我们可以执行 ，kubectl cp started.html nginx-demo:/usr/share/nginx/html/  改变就绪探针的结果，效果如下：

[root@k8s-master ~]# kubectl get po
NAME         READY   STATUS    RESTARTS   AGE
nginx-demo   0/1     Running   0          13m
[root@k8s-master ~]# kubectl cp started.html nginx-demo:/usr/share/nginx/html/
[root@k8s-master ~]# kubectl get po
NAME         READY   STATUS    RESTARTS   AGE
nginx-demo   0/1     Running   0          13m
[root@k8s-master ~]# kubectl get po
NAME         READY   STATUS    RESTARTS   AGE
nginx-demo   1/1     Running   0          13m
[root@k8s-master ~]# kubectl describe pod nginx-demo
Name:         nginx-demo
Namespace:    default
Priority:     0
Node:         k8s-node2/192.168.113.122
Start Time:   Thu, 07 Sep 2023 22:55:23 +0800
Labels:       <none>
Annotations:  cni.projectcalico.org/containerID: b2a16d93bb97564900351dc36dbdc1b0714fa4d344bf8d0ec6361c647311d63e
              cni.projectcalico.org/podIP: 10.224.169.135/32
              cni.projectcalico.org/podIPs: 10.224.169.135/32
Status:       Running
IP:           10.224.169.135
IPs:
  IP:  10.224.169.135
Containers:
  nginx:
    Container ID:   docker://45572be22ee60b8f62143a3890308775562cede4c2c1828128dbbd693f8f9459
    Image:          nginx:1.7.9
    Image ID:       docker-pullable://nginx@sha256:e3456c851a152494c3e4ff5fcc26f240206abac0c9d794affb40e0714846c451
    Port:           80/TCP
    Host Port:      0/TCP
    State:          Running
      Started:      Thu, 07 Sep 2023 22:55:25 +0800
    Ready:          True
    Restart Count:  0
    Readiness:      http-get http://:80/started.html delay=0s timeout=3s period=10s #success=1 #failure=5
    Startup:        exec [sh -c sleep 1;echo success > /inited] delay=0s timeout=5s period=10s #success=1 #failure=3
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-jq6wz (ro)
Conditions:
  Type              Status
  Initialized       True
  Ready             True
  ContainersReady   True
  PodScheduled      True
Volumes:
  kube-api-access-jq6wz:
    Type:                    Projected (a volume that contains injected data from multiple sources)
    TokenExpirationSeconds:  3607
    ConfigMapName:           kube-root-ca.crt
    ConfigMapOptional:       <nil>
    DownwardAPI:             true
QoS Class:                   BestEffort
Node-Selectors:              <none>
Tolerations:                 node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
                             node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
  Type     Reason     Age                   From               Message
  ----     ------     ----                  ----               -------
  Normal   Scheduled  13m                   default-scheduler  Successfully assigned default/nginx-demo to k8s-node2
  Normal   Pulled     13m                   kubelet            Container image "nginx:1.7.9" already present on machine
  Normal   Created    13m                   kubelet            Created container nginx
  Normal   Started    13m                   kubelet            Started container nginx
  Warning  Unhealthy  3m25s (x68 over 13m)  kubelet            Readiness probe failed: HTTP probe failed with statuscode: 404
[root@k8s-master ~]# kubectl get po
NAME         READY   STATUS    RESTARTS   AGE
nginx-demo   1/1     Running   0          13m
[root@k8s-master ~]#

 

 

 

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