How to create a VM with KVM Hypervisor

Install all the dependencies needed

ShellScript

sudo apt install -y qemu qemu-kvm libvirt-daemon libvirt-daemon-system virtinst libvirt-clients bridge-utils virt-manager cloud-image-utils libguestfs-tools

Reboot, that may work better.

Download an image, for example Ubuntu 20.04

ShellScript

# Ubuntu 20.04
wget https://cloud-images.ubuntu.com/releases/focal/release/ubuntu-20.04-server-cloudimg-amd64.img

# Ubuntu 22.04
wget https://cloud-images.ubuntu.com/releases/22.04/release/ubuntu-22.04-server-cloudimg-amd64.img

Create user data file so we can login after installation

ShellScript

cat >user-data.txt <<EOF
#cloud-config
hostname: bm1-vm00
system_info:
  default_user:
    name: root
    home: /root
sudo: ALL=(ALL) NOPASSWD:ALL
password: secretpassword
chpasswd: { expire: False }
ssh_pwauth: True
EOF

Create a disk for cloud-init to utilize nocloud

ShellScript

USER_DATA_IMG=user-data.img
cloud-localds $USER_DATA_IMG user-data.txt

Create disk from image

ShellScript

DISK_SIZE=100G
QEMU_IMAGE=vm-disk-0.qcow2
qemu-img create -b ubuntu-20.04-server-cloudimg-amd64.img -F qcow2 -f qcow2 $QEMU_IMAGE $DISK_SIZE

If you run from root user

ShellScript

nano /etc/libvirt/qemu.conf

and uncomment user = "root" and group = "root" and run

ShellScript

service libvirtd restart

Install Virtual Machine

ShellScript

VM_NAME=vm-0
MEMORY_AMOUNT=4000000 # in MiB, that gives 4096 MB
VCPUS=4
virt-install --name $VM_NAME \
  --virt-type kvm --memory $MEMORY_AMOUNT --vcpus $VCPUS \
  --boot hd,menu=on \
  --disk path=$QEMU_IMAGE,device=disk \
  --disk path=$USER_DATA_IMG,format=raw \
  --graphics none \
  --os-type Linux --os-variant ubuntu20.04

Useful virsh commands

ShellScript

# List VMs
virsh list --all

# Edit VM configuration
virsh edit $VM_NAME

# Log into VM
virsh console $VM_NAME

# List networks
virsh net-list --all

# Start network
virsh net-start default
# Autostart network
virsh net-autostart default

# Autostart VM
virsh autostart $VM_NAME

# Shutdown VM
virsh shutdown $VM_NAME
# Force shutdown
virsh destroy $VM_NAME

# Remove VM
virsh undefine $VM_NAME

# Change password (VM has to be shutdown)
virt-customize -a $QEMU_IMAGE --root-password password:new_pwd --uninstall cloud-init

Also, it might be useful to make the VM restarting on crush. Edit on_crash VM configuration part like this

XML

<on_crash>restart</on_crash>

Other useful commands

ShellScript

# Change root password
passwd root

How to create a VM with KVM Hypervisor

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