Creates a CentOS8 qcow2 image

el8-image.sh

#!/bin/bash
# From a vanilla centos7 installation

yum -y install centos-release-qemu-ev
yum -y install libvirt-install libvirt qemu-kvm-ev
systemctl enable --now libvirtd
curl https://git.centos.org/centos/kickstarts/raw/master/f/CentOS-8-GenericCloud.ks -o /var/tmp/CentOS-8-GenericCloud.ks
virt-install \
  --name c8-genericcloud \
  --vcpus 4 \
  --memory memory=4096 \
  --disk path=/var/lib/libvirt/images/c8-genericcloud.qcow2,size=20,format=qcow2,device=disk,bus=virtio,cache=none \
  --nographics \
  --network network=default \
  --hvm --accelerate \
  --autostart --wait=-1 \
  --noautoconsole \
  --initrd-inject=/var/tmp/CentOS-8-GenericCloud.ks \
  --extra-args "console=ttyAMA0 console=ttyS0 net.ifnames=0 ks=file:/CentOS-8-GenericCloud.ks" \
  --location http://mirror.centos.org/centos-8/8/BaseOS/x86_64/os/
virsh destroy c8-genericcloud
# Compress from ~1.8GB to ~700MB
qemu-img convert -O qcow2 -c c8-genericcloud.qcow2 c8-genericcloud-compressed.qcow2