In /etc/default/halt setup HALT=halt, in bios setup option to start after power fail.
--kill-on-powerfail option helps when power came back while ubuntu shutdown on power fail by apcupsd. UPS will power off (and then on) server anyway (even if power already came back) for server rebooting (without --kill-on-powerfail server halt forever) IMHO it's rather important.
In /etc/default/halt setup HALT=halt, in bios setup option to start after power fail.
--kill-on-powerfail option helps when power came back while ubuntu shutdown on power fail by apcupsd. UPS will power off (and then on) server anyway (even if power already came back) for server rebooting (without --kill-on-powerfail server halt forever) IMHO it's rather important.