containerSpec says a changed cadence moves the marker so the install is
reported updated and re-established. Which containers are held still is the
same kind of statement, and a declaration that changed it while the machine
reported no change would be a machine quietly holding yesterday's containers.
while-stopped names resource ids of the same module's containers; the host
stops them before the run and starts them again after it, in reverse order,
whatever the step did. The restart is deferred before the first stop and runs
on its own context, because the one real risk of this field is a window that
never closes.
Scheduled steps only: at apply the declaration is applied in order and a
run-once step already gates what follows.
jschoubben