debian kvm virsh install with cloud init

This repo describes how to auto install debain12 and debian13 with virsh-install and cloud-init. Which images you can use, and which images you should not use. How to add user passwords with hashes and how to create harddisk images from templates.

sources for images

• https://cdimage.debian.org/cdimage/cloud/
• https://cloud-images.ubuntu.com/noble/current/

get debian image

Do not use genericcloud images, they do not contain sata ahci drivers for cloud init.

cd /isos
wget https://cdimage.debian.org/cdimage/cloud/bookworm/latest/debian-12-generic-amd64.qcow2
wget https://cdimage.debian.org/cdimage/cloud/trixie/latest/debian-13-generic-amd64.qcow2

prepare cloud init file

This python script asks for username, password, list all public ssh keys to select one. It uses this information to update the cloud-init.yml template. It needs mkpasswd (packaged with whois) to create the hash for the user password.

sudo apt-get install whois # to get mkpasswd binary

python3 update-cloud-init.py

create cloud init

mkpasswd -m sha-512 # to generate hash for your user password
cp cloud-init.yml /isos # copy cloud-init.yaml with inserted values

check supported os variant list

virt-install --os-variant list

virsh net-start host-bridge # check if host-bridge is running

Create base hard disk image and install debian12 with cloud init

# create disk image for vm
qemu-img create -f qcow2 -o backing_file=/isos/debian-12-generic-amd64.qcow2,backing_fmt=qcow2 /isos/debian-12.qcow2 30G 

virt-install \
  --name debian12 \
  --memory 4096 \
  --vcpus 4\
  --disk /isos/debian-12.qcow2,device=disk,bus=virtio \
  --os-variant debian12 \
  --virt-type kvm \
  --graphics none \
  --console pty,target_type=serial \
  --network network=default,model=virtio \
  --network bridge=virbr0,model=virtio \
  --cloud-init user-data=/isos/cloud-init.yml \
  --import

Create base hard disk image and install debian13 with cloud init (needs uefi)

# create disk image for vm
qemu-img create -f qcow2 -o backing_file=/isos/debian-13-generic-amd64.qcow2,backing_fmt=qcow2 /isos/debian-13.qcow2 30G

virt-install \
  --name debian13 \
  --memory 4096 \
  --vcpus 4\
  --disk /isos/debian-13.qcow2,device=disk,bus=virtio \
  --os-variant debian13 \
  --virt-type kvm \
  --graphics none \
  --console pty,target_type=serial \
  --network network=default,model=virtio \
  --cloud-init user-data=/isos/cloud-init.yml \
  --boot uefi \
  --import

if install works for your usecase add following parameter for background install

virt-install \
...
--noautoconsole \

delete vms

virsh shutdown debian12
virsh destroy debian12
virsh undefine debian12

virsh shutdown debian13
virsh destroy debian13
virsh undefine debian13

cloud init tools

check cloud-init status

sudo journalctl -u cloud-init
sudo cat /var/log/cloud-init.log

trigger cloud init

sudo cloud-init clean
sudo cloud-init init
sudo cloud-init modules --mode=config
sudo cloud-init modules --mode=final