RHEL Merge /boot into root

So some times you try to install a kernel on a RHEL system and discover the /boot is way too small to keep 3 kernels. To resolve this you need to either resize /boot, this can be very hard if using bare partitions; or merge /boot into the root filesystem.

The former is a well know process especially on lvm, the later is partially documented but this brings all the steps together.

$ umount /boot
$ mount /dev/sda1 /mnt
$ cd /mnt
$ rsync -avHAX . /boot/
$ mkdir .bak
$ mv * .bak/
$ cd /
$ umount /mnt
$ remove /boot from /etc/fstab
$ dracut -v -f
$ grub2-mkconfig -o /boot/grub2/grub.cfg
$ grub2-install /dev/sda
$ init 6