Add a SCRIPT HOLD feature to DAGMan

Description

(This issue was previously gittrac #7781)

A couple different people have been asking about adding a mechanism into DAGMan that will execute a script when jobs go on hold.
Initially we talked about executing the POST script when jobs go on hold, but this results in really ugly semantics and conditions in the code that can only lead to pain and sorrow.

Instead, we propose adding a brand new HOLD script into condor_dagman that can be defined in a .dag file as follows:

This script will execute using similar mechanics to the pre and post scripts. One major difference is it will have no bearing on the final status of the node; whether or not a hold script succeeds, the dag will continue processing as per usual.

A design doc is available here: https://docs.google.com/document/d/1HkdeFP-yrYUEEPHoSqGzJFc-lZy_Nf1Qqi3NMJ4rc8I/edit#

Done

Time remaining

0m

Assignee

Mark Coatsworth