Simos Xenitellis: How to run a Linux Desktop virtual machine on Incus

Incus is a manager for virtual machines and system containers.

A virtual machine (VM) is an instance of an operating system that runs on a computer, along with the main operating system. A virtual machine uses hardware virtualization features for the separation from the main operating system. With virtual machines, the full operating system boots up in them. While in most cases you would run Linux on a VM without a desktop environment, you can also run Linux with a desktop environment (like in VirtualBox and VMWare).

In How to run a Windows virtual machine on Incus on Linux we saw how to run a run a Windows VM on Incus. In this post we see how to run a Linux Desktop virtual machine on Incus.

Updates

No updates yet.

Prerequisites

You should have a system that runs Incus.
A system with support for hardware virtualization so that it can run virtual machines.
A virtual machine image of your preferred Linux desktop distribution.

Cheat sheet

Availability of images

Currently, Incus provides you with the following VM images of Linux desktop distributions. The architecture is x86_64.

Run the following command to list all available Linux desktop images. incus image is the section of Incus that deals with the management of images. The list command lists the available images of a remote/repository, the default being images: (run incus remote list for the full list of remotes). After the colon (:), you type filter keywords, and in this case we typed desktop to show images that have the word desktop in them (to show only Desktop images). We are interested in a few columns only, therefore -c ldt only shows the columns for the Alias, the Description and the Type.

$ incus image list images:desktop -c ldt
+------------------------------------------+---------------------------+-----------------+
|                  ALIAS                   |      DESCRIPTION          |      TYPE       |
+------------------------------------------+---------------------------+-----------------+
| archlinux/desktop-gnome (3 more)         | Archlinux current amd64   | VIRTUAL-MACHINE |
+------------------------------------------+---------------------------+-----------------+
| opensuse/15.5/desktop-kde (1 more)       | Opensuse 15.5 amd64       | VIRTUAL-MACHINE |
+------------------------------------------+---------------------------+-----------------+
| opensuse/15.6/desktop-kde (1 more)       | Opensuse 15.6 amd64       | VIRTUAL-MACHINE |
+------------------------------------------+---------------------------+-----------------+
| opensuse/tumbleweed/desktop-kde (1 more) | Opensuse tumbleweed amd64 | VIRTUAL-MACHINE |
+------------------------------------------+---------------------------+-----------------+
| ubuntu/24.10/desktop (3 more)            | Ubuntu oracular amd64     | VIRTUAL-MACHINE |
+------------------------------------------+---------------------------+-----------------+
| ubuntu/focal/desktop (3 more)            | Ubuntu focal amd64        | VIRTUAL-MACHINE |
+------------------------------------------+---------------------------+-----------------+
| ubuntu/jammy/desktop (3 more)            | Ubuntu jammy amd64        | VIRTUAL-MACHINE |
+------------------------------------------+---------------------------+-----------------+
| ubuntu/noble/desktop (3 more)            | Ubuntu noble amd64        | VIRTUAL-MACHINE |
+------------------------------------------+---------------------------+-----------------+
| ubuntu/plucky/desktop (1 more)           | Ubuntu plucky amd64       | VIRTUAL-MACHINE |
+------------------------------------------+---------------------------+-----------------+
$

These images have been generated with the utility distrobuilder, https://github.com/lxc/distrobuilder The purpose of the utility is to prepare the images so that when we launch them, we get immediately the desktop environment and do not perform any manual configuration. The configuration files for distrobuilder to create these images can be found at https://github.com/lxc/lxc-ci/tree/main/images For example, the archlinux.yaml configuration file has a section to create the desktop image, along with the container and other virtual machine images.

The full list of Incus images are also available on the Web, through the website https://images.linuxcontainers.org/ It is possible to generate more such desktop images by following the steps of the existing configuration files. Perhaps a Kali Linux desktop image would be very useful. In the https://images.linuxcontainers.org/ website you can also view the build logs that were generated while building the images, and figure out what parameters are needed for distrobuilder to build them (along with the actual configuration file). For example, here are the logs for the ArchLinux desktop image, https://images.linuxcontainers.org/images/archlinux/current/amd64/desktop-gnome/

Up to this point we got a list of the available virtual machine images that are provided by Incus. We are ready to boot them.

Booting a desktop Linux VM on Incus

When launching a VM, Incus provides by default 1GiB RAM and 10GiB of disk space. The disk space is generally OK, but the RAM is too little for a desktop image (it’s OK for non-desktop images). For example, for an Ubuntu desktop image, the instance requires about 1.2GB of memory to start up and obviously more to run other programs. Therefore, if we do not specify more RAM, then the VM would struggle to make do of the mere 1GiB of RAM.

Booting the Ubuntu desktop image on Incus

Here is the command to launch a desktop image. We use incus launch to launch the image. It’s a VM, hence --vm. We are using the image from the images: remote, the one called ubuntu/plucky/desktop (it’s the last from the list of the previous section). We configure a new limit for the memory usage, -c limits.memory=3GiB, so that the instance will be able to run successfully. Finally, the console is not textual but graphical. We specify that with --console=vga which means that Incus will launch the remote desktop utility for us.

$ incus launch --vm images:ubuntu/plucky/desktop mydesktop -c limits.memory=3GiB --console=vga
Launching mydesktop

Here is a screenshot of the new window with the running desktop virtual machine.

Now we closed the wizard.

Booting the ArchLinux desktop image on Incus

I cannot get this image to show the desktop. If someone can make this work, please post in a comment.

$ incus launch --vm images:archlinux/desktop-gnome mydesktop -c limits.memory=3GiB --console=vga -c security.secureboot=false
Launching mydesktop

Booting the OpenSUSE desktop image on Incus

$ incus launch --vm images:opensuse/15.5/desktop-kde mydesktop -c limits.memory=3GiB --console=vga
Launching mydesktop

Troubleshooting

I closed the desktop window but the VM is running. How do I get it back up?

If you closed the Remote Viewer window, you can get Incus to start it again with the following command. By doing so, you are actually reconnecting back to the VM and continue working from where you left off.

We are using the incus console action to connect to the running mydesktop instance and request access through the Remote Viewer (rather than a text console).

$ incus console mydesktop --type=vga

Error: This console is already connected. Force is required to take it over.

You are already connected to the desktop VM with the Remote Viewer and you are trying to connect again. Either go to the existing Remote Viewer window, or add the parameter --force to close the existing Remote Viewer window and open a new one.

Error: Instance is not running

You are trying to connect to a desktop VM with the Remote Viewer but the instance (which already exists) is not running. Use the action incus start to start the virtual machine, along with the --type=vga parameter to get Incus to launch the Remote Viewer for you.

$ incus start mydesktop --console=vga

I get no audio from the desktop VM! How do I get sound in the desktop VM?

This requires extra steps which I do not show yet. There are three options. The first is to use the QEMU device emulation to emulate a sound device in the VM. The second is to somehow push an audio device into the VM so that this audio device is used exclusively in the VM (have not tried this but I think it’s possible). The third and perhaps best option is to use network audio with PulseAudio/Pipewire. You enable network audio on your desktop and then configure the VM instance to connect to that network audio server. I have tried that and it worked well for me. The downside is that the Firefox snap package in the VM could not figure out that there is network audio there and I could not get audio in that application.

How do I shutdown the desktop VM?

Use the desktop UI to perform the shutdown. The VM will shut down cleanly.

Error: Failed instance creation: The image used by this instance is incompatible with secureboot. Please set security.secureboot=false on the instance

You tried to launch a virtual machine with SecureBoot enabled but the image does not support SecureBoot. You need to disable SecureBoot when you launch this image. The instance has been created but is unable to run unless you disable SecureBoot. You can either disable SecureBoot through an Incus configuration for this image, or just delete the instance, and try again with the parameter -c security.secureboot=false.

Here is how to disable SecureBoot, then try to incus start that instance.

$ incus config set mydesktop security.secureboot=true

Here is how you would enable that flag when you launch such a VM.

incus launch --vm images:archlinux/desktop-gnome mydesktop -c limits.memory=3GiB --console=vga -c security.secureboot=false

Note that official Ubuntu images can work with SecureBoot enabled, most others don’t. It has to do with the Linux kernel being digitally signed by some certification authority.

Error: Failed instance creation: Failed creating instance record: Add instance info to the database: Failed to create “instances” entry: UNIQUE constraint failed: instances.project_id, instances.name

This error message is a bit cryptic. It just means that you are trying to create or launch an instance while the instance already exists. Read as Error: The instance name already exists.

Simos Xenitellis

blog.simos.info/

from Planet Ubuntu https://ift.tt/174oeFW

Simos Xenitellis: How to run a Linux Desktop virtual machine on Incus

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