automatically resize the root partition on first boot

 This package adds functionality to an initramfs built by initramfs-tools.
 When installed, the initramfs will repartition a disk to make the
 root volume consume all space that follows it.
 .
 You most likely do not want this package unless you know what you are
 doing. It is primarily interesting in a virtualized environment when
 a disk can be provisioned with a size larger than its original size.
 In this case, with this package installed, you can automatically use
 the new space without requiring a reboot to re-read the partition table.