How to negate exit code status to be used in Kubernetes livenessProbe?

Question

How to negate exit code status to be used in Kubernetes livenessProbe?

I'll be using the grep command and I would like to do below as a check.

Return exit value 0, if grep has no hit
Return exit value 1, if grep has a hit

Since normally, grep will return 0 if there is a hit, can I negate this something like shown below?

!$(cat filet.txt | grep keyword)

Harsh Manvar · Accepted Answer · 2021-09-23T05:25:11.793

2

Yes you can give it try

example :

    livenessProbe:
  exec:
    command:
    - /bin/bash
    - -c
    - cat filet.txt | grep keyword
  initialDelaySeconds: 10
  periodSeconds: 10

you should checkout if helpful

-v, --invert-match
          Invert the sense of matching, to select non-matching lines.

You can also try -c

echo 'Test' | grep -c T

1

echo 'Test' | grep -c N

0

shell script

#!/bin/sh
if [ $(echo 'Test' | grep -c T) ]; then
  exit 1
else
  exit 0
fi

the easiest way would be writing shell script and managing the exit code for liveness as you want 0 or 1 and based on that liveness will restart the pod.

livenessProbe:
  exec:
    command:
    - /bin/sh
    - -c
    - /home/test/health.sh

edited Sep 23 '21 at 05:25

answered Sep 23 '21 at 04:26

Harsh Manvar

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in your example, the pod will retart if there are no hits ? – lemont80 Sep 23 '21 at 05:17
1

i think, but easiest way would be using the shell script option last one I have shared, that will be good to manage the exit status code and manage code as per need. – Harsh Manvar Sep 23 '21 at 05:25
1

I will give the shell script approach a try. I think it is the better solution. Can you upvote my question bro? I can't upvote your answer for now since I still have less rep :( – lemont80 Sep 23 '21 at 05:39
1

it worked man. Really helped a lot. – lemont80 Sep 23 '21 at 07:12
glad to hear that...! – Harsh Manvar Sep 23 '21 at 08:45
1

There a little issue with the answer. All cases will lead to exit 1 path. – lemont80 Sep 23 '21 at 10:28
1

It's just an info bro, no need to edit. I just added a conditional operator to make it work. – lemont80 Sep 23 '21 at 11:51
got it, thanks for update. however you can share please might be helpful to others. – Harsh Manvar Sep 23 '21 at 12:00

How to negate exit code status to be used in Kubernetes livenessProbe?

1 Answers1