Comment 4 for bug 1236930

On 10/10/2013 08:00 AM, Jay Lau wrote:
> what about simply let nova compute report error directly if reboot a not
> running vm?

That's fine by me, though it would mean an incompatible change in
behavior. I don't what the policy is on such things.

> How to enable "soft reboot attempt can do a better job of checking for
> failures"? Can you please give more detail?

I mean currently, I'm guessing the logic is something like this:

soft_reboot()
while 2 minutes have not elapsed {
  if instance has rebooted {
    return success
  }
}
hard_reboot()

When the soft reboot is attempted, there must be some error, because it
is logged (can't reboot a shutdown instance). But, it has absolutely no
bearing on the reboot procedure; it just waits two minutes, even though
it's clear (from the error) that the soft reboot has failed. The logic
could be this:

try {
  soft_reboot()
} catch {
  hard_reboot()
}
while 2 minutes have not elapsed {
  if instance has rebooted {
    return success
  }
}
hard_reboot()

Or, if a change in behavior is acceptable, as you suggest, it could be:

if instance is not running {
  return failure "can not reboot a non-running instance"
}
...reboot as it is currently done

Either way, the confusion is eliminated.