Are you sure you want to attach your callout to ComputeContainer_EXECUTE_SCRIPT? I assume you are trying to do an Operator Action callout?
In any case, you must define an "input" context item in your AO Process. The CsmRequest JSON will be passed to that context item.
Thanks for your reply. Yes, I am doing the Operator Action callout. I was not aware that my input context item should be names as "input". After changing the context item name to "input", I am able to get the csmreqeust into the AO workflow.