I was wondering whether it's possible to setup an even handler kind of thing which would trigger an action/function whenver a vm is bootstraping. Not loading the OS, but bootstraping- the stage before OS loads.
Time to time there are operations I need to perform which require to power down a vm, or all vms on a lun or on a host. It's difficult to schedule a down time, since the vms are used by multiple teams. If the even handler thing was possible, I could just setup a script which would perform the desired action as soon as the user reboots (from within the OS). The end user won't notice anything (except some delay until the vm comes back online) and I get my tasks done. E.g. I need to redo a LUN, but can't vmotion some vms since they have snapshots. The task is not critical/urgent, so I would give it few weeks. After that there is a big chance all (or most) vms were rebooted and migrated somewhere else.