quickly setting up a virtual machine on libvirt | https://gitlab.com/uhurutec/utils/setup-vm

Find a file

Matthias Haag 12d077478d Fix behaviour for Ubuntu 25.10 The behaviour of the comm utility seems to have changed. However ignorinng the sort order is usable and more robust for the given use case. Signed-off-by: Matthias Haag <matthias.haag@uhurutec.com>		2025-12-17 16:27:13 +01:00
.gitlab/merge_request_templates	Add gitlab MR template	2025-07-11 11:30:58 +02:00
LICENSES	Add SPDX annotations	2024-04-10 21:10:46 +02:00
.editorconfig	Add SPDX annotations	2024-04-10 21:10:46 +02:00
.gitlab-ci.yml	Add SPDX annotations	2024-04-10 21:10:46 +02:00
LICENSE	Use pristine AGPL license text	2023-06-14 08:58:48 +02:00
README.md	Update license headers	2025-07-11 11:33:07 +02:00
REUSE.toml	Add gitlab MR template	2025-07-11 11:30:58 +02:00
setup-vm.sh	Fix behaviour for Ubuntu 25.10	2025-12-17 16:27:13 +01:00

README.md

setup-vm

The script setup-vm.sh can be used for quickly setting up a virtual machine on libvirt.

Setting up a virtual machine manually for testing purpose can be tedious. There are tools for setting up virtual machines in an automized way, e.g. vagrant, but they often have many dependencies or require to write a configuration file in a certain language.

This script uses cloud-init for customizations and therefore requires base images from upstream, which support cloud-init. Those base images will be downloaded and cached as required on the fly.

Usage

The script takes one obligatory parameter: the name of the virtual machine (domain in libvirt terminology).

$ ./setup-vm.sh test-machine
[ INFO] Setting up machine "test-machine"
[ INFO]       CPUs:          2    Memory:     4096
[ INFO]  Disk Size:        20G    Format:    qcow2
[ INFO]         OS:  debian-11
[ INFO] Preparing disk image "/var/lib/libvirt/images/test-machine/root.qcow2"
[ INFO] Setting up machine "test-machine"
[ INFO] Machine test-machine is now ready. You can start it with
[ INFO]     virsh -c qemu:///system start test-machine

For additional usage information see the help message of the script.

$ ./setup-vm.sh --help

Accessing the Virtual Machine

You can access the started virtual machine via SSH using the same username, which was used to execute setup-vm.sh or was provided in combination with the -u parameter.

Preconditions

Dependencies

curl for retrieving the base image
comm from coreutils
fmt from coreutils
getent from glibc
id, usually provided either by coreutils or by Busybox
qemu-img for resizing disk images
cloud-localds from cloud-image-utils for generating the configuration image for cloud-init
genisoimage from cdrtools (a dependency of cloud-image-utils)
sed (the Stream EDitor)
sort from coreutils
virt-install for setting up the virtual machine
virsh for controlling libvirt
xmllint from libxml for parsing libvirt XML data

On debian or its derivatives the required packages can be installed with:

# apt-get install cloud-image-utils curl libvirt-clients libvirt-daemon-system libxml2-utils openssh-client qemu-utils virtinst

Remote and Hypervisor Support

The script supports Qemu/KVM hypervisor on the local machine and remote machine via SSH transport by setting the connection URI (-c parameter). Other hypervisors or transports are not supported. Refer to the documentation of libvirt connection URIs for details.

Permissions

The user libvirt-qemu must be able to access /var/lib/libvirt/images, which has been reported not to hold by default on Ubuntu 22.04. This would manifest in messages like

[ERROR] Directory "/var/lib/libvirt/images" is not accessible!

One solution is to use the existing kvm group for granting access:

# chown :kvm /var/lib/libvirt/images
# chmod 2775 /var/lib/libvirt/images

License

This project is licensed under the GNU Affero General Public License 3 - see the LICENSE file for details