Kubernetes - What happens if startupProbe runs beyond periodSeconds - kubernetes

Question

I have a Deployment which runs a simple apache server. I want to execute some commands after the service is up. I am not quite sure how much time the post action commands going to take. I have "timeoutSeconds" set as more than "periodSeconds".
Kubernets Version: 1.25
apiVersion: apps/v1
kind: Deployment
metadata:
name: readiness
spec:
replicas: 1
selector:
matchLabels:
app: readiness
template:
metadata:
labels:
app: readiness
spec:
containers:
- image: sujeetkp/readiness:3.0
name: readiness
resources:
limits:
memory: "500M"
cpu: "1"
readinessProbe:
httpGet:
path: /health_monitor
port: 80
initialDelaySeconds: 20
timeoutSeconds: 10
failureThreshold: 20
periodSeconds: 10
livenessProbe:
httpGet:
path: /health_monitor
port: 80
initialDelaySeconds: 60
timeoutSeconds: 10
failureThreshold: 20
periodSeconds: 10
startupProbe:
exec:
command:
- /bin/sh
- -c
- |-
OUTPUT=$(curl -s -o /dev/null -w %{http_code} http://localhost:80/health_monitor)
if [ $? -eq 0 ] && [ $OUTPUT -ge 200 ] && [ $OUTPUT -lt 400 ]
then
echo "Success" >> /tmp/post_action_track
if [ ! -f /tmp/post_action_success ]
then
# Trigger Post Action
sleep 60
echo "Success" >> /tmp/post_action_success
fi
else
exit 1
fi
initialDelaySeconds: 20
timeoutSeconds: 80
failureThreshold: 20
periodSeconds: 10
When I run this code, I see very strange results.
As "periodSeconds" is 10 and my script has a sleep of 60 seconds, should not the start up probe trigger atleast 6 times, but it only triggers 2 times.
I am checking the contents of files /tmp/post_action_success and /tmp/post_action_track to identify how many times the probe triggers. (Count the number of success inside the files)
Question: If the previous instance of startup probe is running, then is the startupProbe triggered on top of it or not ? If yes, then why it triggered only twice in my case.
Another observation:
When I set below options
initialDelaySeconds: 20
timeoutSeconds: 5
failureThreshold: 20
periodSeconds: 10
Then the content of file /tmp/post_action_success shows sleep/timeoutSeconds (60/5)=12 "success".
Can someone please explain how this works.

Answer 1

I think the reason you see the probe being triggered twice is because of timeoutSeconds: 80. See this question. Also the official doc is quiet handy in explaining the other fields.
Perhaps you can set initialDelaySeconds: 61 instead of using sleep in you script?