OpenShift aPaaS v3 失败的 Liveness 探测与失败的 Readiness 探测

Question

如果 pod Liveness 探测池中的一个池和 pod Readiness 探测池中的一个失败，会发生什么情况？

Answer 1

活性探测和就绪探测之间几乎没有什么区别。但主要区别之一是准备就绪探测失败会从池中删除 pod，但不要重新启动。另一方面，失败的 liveness 探测会从池中删除 pod 并重新启动 pod。

apiVersion: v1
kind: Pod
metadata:
  labels:
    test: liveness-vs-readiness
  name: liveness-vs-readiness-exec
spec:
  containers:
  - name: liveness
    image: k8s.gcr.io/busybox
    args:
    - /bin/sh
    - -c
    - touch /tmp/healthy; touch /tmp/liveness; sleep 999999
    livenessProbe:
      exec:
        command:
        - cat
        - /tmp/liveness
      initialDelaySeconds: 5
      periodSeconds: 5
    readinessProbe:
      exec:
        command:
        - cat
        - /tmp/healthy
      initialDelaySeconds: 5
      periodSeconds: 5

让我们创建这个 pod 并展示它的实际效果：oc create -f liveness-vs-readiness.yaml

当我们在 pod 中执行操作时输出 pod 状态。名字前面的数字对应pod内完成的动作：

 oc get pods -w
NAME                         READY     STATUS    RESTARTS   AGE
[1] liveness-vs-readiness-exec   1/1       Running   0         44s
[2] liveness-vs-readiness-exec   0/1       Running   0         1m
[3] liveness-vs-readiness-exec   1/1       Running   0         2m
[4] liveness-vs-readiness-exec   0/1       Running   1         3m
    liveness-vs-readiness-exec   1/1       Running   1         3m

容器内的操作：

[root@default ~]# oc rsh liveness-vs-readiness-exec 
# [1] we rsh to the pod and do nothing. Pod is healthy and live
# [2] we remove health probe file and see that pod goes to notReady state
# rm /tmp/healthy 
# 
# [3] we create health file. Pod goes into ready state without restart
# touch /tmp/healthy
# 
# [4] we remove liveness file. Pod goes into notready state and is restarted just after that
# rm /tmp/liveness 
# command terminated with exit code 137

OpenShift aPaaS v3 失败的 Liveness 探测与失败的 Readiness 探测

OpenShift aPaaS v3 failed Liveness probes vs failed Readiness Probes

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