pod没有将状态从unready变为ready

Question

我在k8s pod中使用准备就绪探测功能。为此，probe检查/tmp/healthy文件是否存在。如果不是，则探测"UN-READY"标记。我观察到，如果我再次创建/tmp/healthy文件，pod不会回到READY状态。这是否意味着，在pod的生命周期中，只有一条READY->不准备，反之亦然?

/home/ravi/for_others/ric/stub>kubectl describe pod -n myns  deployment-eterm
Name:         deployment-eterm
Namespace:    myns
Priority:     0
Status:       Running
IP:           192.168.252.87
IPs:
IP:           192.168.252.87
Controlled By:  ReplicaSet/deployment-myns-eterm-micro-6b896556c8
Containers:
Liveness:       exec [/bin/sh -c /tmp/liveliness-status-collector.sh] delay=60s timeout=1s period=2s #success=1 #failure=5
Readiness:      exec [/bin/sh -c cat /tmp/healthy] delay=60s timeout=1s period=10s #success=1 #failure=1
Environment Variables from:
configmap-myns-eterm-env-micro  ConfigMap  Optional: false
Environment:                       <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-57jpz (ro)
Conditions:
Type              Status
Initialized       True
Ready             False
ContainersReady   False
PodScheduled      True
Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
node.kubernetes.io/unreachable:NoExecute for 300s
Events:
Type     Reason     Age               From                    Message
----     ------     ----              ----                    -------
Normal   Scheduled  9m11s             default-scheduler       Successfully assigned myns/deployment-eterm to mnode
Normal   Pulled     9m10s             kubelet, mnode  Container image "porics.microlab.com:5000/eterm:latest" already present on machine
Normal   Created    9m10s             kubelet, mnode  Created container container-myns-eterm
Normal   Started    9m10s             kubelet, mnode  Started container container-myns-eterm
Normal   Pulled     9m10s             kubelet, mnode  Container image "porics.microlab.com:5000/config-proxy:latest" already present on machine
Normal   Created    9m10s             kubelet, mnode  Created container container-myns-configproxy
Normal   Started    9m10s             kubelet, mnode  Started container container-myns-configproxy
Warning  Unhealthy  3s (x3 over 23s)  kubelet, mnode  Readiness probe failed: cat: /tmp/healthy: No such file or directory
/home/ravi/for_others/ric/stub>

Answer 1

下面的语句不正确:

这是否意味着，在pod生命周期中，只有一条READY路径——>UN-READY但反之亦然?

您可以运行下面的实验来查看pod转换:

用下面的manifest文件创建一个pod:

apiVersion: v1
kind: Pod
metadata:
labels:
test: readiness
name: readiness-test
spec:
nodeName: kube-master
containers:
- name: liveness
image: bash
command: ['bash','-c', 'while true;do echo "$(date): creating /tmp/healthy"; touch /tmp/healthy; sleep 10; echo "$(date): deleting /tmp/healthy";rm /tmp/healthy ;sleep 10;done']
readinessProbe:
exec:
command:
- cat
- /tmp/healthy
initialDelaySeconds: 5
periodSeconds: 2

上述清单将导致pod每10秒转换为ready/not-ready。

kubectl get pod -w
NAME             READY   STATUS    RESTARTS   AGE
readiness-test   0/1     Running   0          79s
readiness-test   1/1     Running   0          83s
readiness-test   0/1     Running   0          97s
readiness-test   1/1     Running   0          103s
readiness-test   0/1     Running   0          117s
readiness-test   1/1     Running   0          2m3s
readiness-test   0/1     Running   0          2m17s
readiness-test   1/1     Running   0          2m23s
readiness-test   0/1     Running   0          2m37s
readiness-test   1/1     Running   0          2m43s
readiness-test   0/1     Running   0          2m57s
readiness-test   1/1     Running   0          3m3s
readiness-test   0/1     Running   0          3m17s
readiness-test   1/1     Running   0          3m23s
readiness-test   0/1     Running   0          3m37s
readiness-test   1/1     Running   0          3m43s
readiness-test   0/1     Running   0          3m57s
readiness-test   1/1     Running   0          4m3s

您可以看到准备状态正在更改:

while true; do k get pod readiness-test -o jsonpath='{.status.containerStatuses[*].ready}{"n"}';sleep 2 ;done
true
true
true
true
true
true
false
false
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true
true
true
false
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false