How can I run export in postStart?

Question

I'm using StatefulSet in kubernetes, and need to get ordinal index of pod.
I tried to export in postStart.exec.command, but it doesn't work for me.

Here is my code I tried.

lifecycle:
  postStart:
    exec:
      command: ["/bin/sh", "-c", "export INDEX=${POD_NAME##*-}"]

How can I export ordinal index?

Answer 1

As per this GitLink and SO Link use postStart.exec.command as below and give a try.

lifecycle:
  postStart:
    exec:
      command: ["/bin/sh", "-c", "export INDEX=${HOSTNAME##*-}"]

Refer to this Gitlink and Doc for more information.

Answer 2

You can create a variable based on the POD name, for example:

env:
 - name: POD_NAME
   valueFrom:
     fieldRef:
       fieldPath: metadata.name

And then, in the post start lifecycle, use TR command to create your ordinary number, example:

lifecycle:
  postStart:
    exec:
      command: 
         - /bin/bash
         - -ec
         - export INDEX=$(echo $POD_NAME|tr -dc '0-9')