当容器转换为就绪时，Kubernetes 就绪探针是否应该发出事件？

Question

我开始在我的服务中引入liveness and readiness probes，我不确定我是否成功地让它工作，因为我无法自信地解释kubectl报告的状态。

kubectl describe pod mypod 给了我这样的东西：

Name:           myapp-5798dd798c-t7dqs
Namespace:      dev
Node:           docker-for-desktop/192.168.65.3
Start Time:     Wed, 24 Oct 2018 13:22:54 +0200
Labels:         app=myapp
                pod-template-hash=1354883547
Annotations:    version: v2
Status:         Running
IP:             10.1.0.103
Controlled By:  ReplicaSet/myapp-5798dd798c
Containers:
  myapp:
    Container ID:   docker://5d39cb47d2278eccd6d28c1eb35f93112e3ad103485c1c825de634a490d5b736
    Image:          myapp:latest
    Image ID:       docker://sha256:61dafd0c208e2519d0165bf663e4b387ce4c2effd9237fb29fb48d316eda07ff
    Port:           80/TCP
    Host Port:      0/TCP
    State:          Running
      Started:      Wed, 24 Oct 2018 13:23:06 +0200
    Ready:          True
    Restart Count:  0
    Liveness:       http-get http://:80/healthz/live delay=0s timeout=10s period=60s #success=1 #failure=3
    Readiness:      http-get http://:80/healthz/ready delay=3s timeout=3s period=5s #success=1 #failure=3
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-gvnc2 (ro)
Conditions:
  Type           Status
  Initialized    True
  Ready          True
  PodScheduled   True
Volumes:
  default-token-gvnc2:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-gvnc2
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
                 node.kubernetes.io/unreachable:NoExecute for 300s
Events:
  Type     Reason                 Age   From                         Message
  ----     ------                 ----  ----                         -------
  Normal   Scheduled              84s   default-scheduler            Successfully assigned myapp-5798dd798c-t7dqs to docker-for-desktop
  Normal   SuccessfulMountVolume  84s   kubelet, docker-for-desktop  MountVolume.SetUp succeeded for volume "default-token-gvnc2"
  Normal   Pulled                 75s   kubelet, docker-for-desktop  Container image "myapp:latest" already present on machine
  Normal   Created                74s   kubelet, docker-for-desktop  Created container
  Normal   Started                72s   kubelet, docker-for-desktop  Started container
  Warning  Unhealthy              65s   kubelet, docker-for-desktop  Readiness probe failed: Get http://10.1.0.103:80/healthz/ready: net/http: request canceled (Client.Timeout exceeded while awaiting headers)

现在，我注意到container 具有Status: Ready，但由于准备就绪探测失败，事件列表中的最后一个事件将状态列为Unhealthy。 （查看应用程序日志，我可以看到从那以后有更多传入请求到就绪探测，并且它们都成功了。）

我应该如何解释这些信息？ Kubernetes 是否认为我的 pod 已准备就绪？

Answer 1

当所有容器的就绪探测返回成功时，一个 pod 就准备好了。在您的情况下，就绪探测在第一次尝试中失败，但下一次探测成功并且容器进入就绪状态。下面是失败的就绪探测示例

下面的就绪探测在最后 11m 内探测了 58 次，但失败了。

Events:
  Type     Reason     Age                  From                                   Message
  ----     ------     ----                 ----                                   -------
  Normal   Scheduled  11m                  default-scheduler                      Successfully assigned default/upnready to mylabserver.com
  Normal   Pulling    11m                  kubelet, mylabserver.com  pulling image "luksa/kubia:v3"
  Normal   Pulled     11m                  kubelet, mylabserver.com  Successfully pulled image "luksa/kubia:v3"
  Normal   Created    11m                  kubelet, mylabserver.com  Created container
  Normal   Started    11m                  kubelet, mylabserver.com  Started container
  Warning  Unhealthy  103s (x58 over 11m)  kubelet, mylabserver.com  Readiness probe failed: Get http://10.44.0.123:80/: dial tcp 10.44.0.123:80: connect: 

容器状态也未准备好，如下所示

kubectl get pods -l run=upnready
NAME       READY   STATUS    RESTARTS   AGE
upnready   0/1     Running   0          17m

在您的情况下，就绪探测通过了运行状况检查，并且您的 pod 处于就绪状态。

您可以有效地利用 initialDelaySeconds,periodSeconds,timeoutSeconds 来获得更好的结果。这是一篇文章。

article on readiness probe and liveness probe