OpenShift aPaaS v3 failed Liveness probes vs failed Readiness Probes - openshift

Question

What will happen if in a pool of pod Liveness probes are failed and a pool of pod Readiness probes are failed ?

Answer 1

There is few more differences between liveness and readiness probes. But one of the main difference is that a failed readiness probe removes the pod from the pool, but DO NOT RESTART. On the other hand a failed liveness probe removes the pod from the pool and RESTARTS the 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
Lets create this pod and show this in action: oc create -f liveness-vs-readiness.yaml
Output of pod status while we do actions inside the pod. Number in front of the name coresponds to the actions done inside the pod:
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
Actions inside the container:
[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