Download https://github.com/mk-fg/dracut-crypt-sshd and unzip
yum groupinstall "Development Tools"
yum install dropbear
cp -R 60dropbear-sshd /usr/lib/dracut/modules.d/
echo 'add_dracutmodules+="dropbear-sshd"' >> /etc/dracut.conf.d/dropbear.conf
echo 'dropbear_port=22' >> /etc/dracut.conf.d/dropbear.conf
Then edit GRUB_CMDLINE_LINUX
line in /etc/default/grub
and add