[rdo-list] Grub timing out too quickly on default CentOS 7 Openstack images.

Hi, I am using the default CentOS7 image on my Openstack setup. When a VM boots, I would like to have at least a 20 seconds to choose the kernel or boot into single user mode. To do so, I have modified the grub_timeout value in /etc/default/grub . Then, when I run grub2-mkconfig -o /boot/grub2/grub.cfg, the VM reboots right away and my changes do not seem to be taken into account. Is there anything I am missing here?