When running an ephemeral slave on EC2 via Jenkins, there's a possibility there may be things left on the slave (logs, artifacts, etc) that one may want to copy before the instance gets terminated. In my case, I have a monitoring tool that monitors every instance I bring up and would like to be able to make an API call and allow the Jenkins slave to remove itself at shutdown. If the instance were to go into disconnect/shutdown mode and then initiate that script before it is finally terminated, this would allow users to run any final cleanup tasks that are required (if any).