Starting in mid-April 2024, it will not be nearly as easy for ChromeOS LXD users to get new LXD images for distributions other than the ubuntu: and ubuntu-daily: remotes from Canonical and the Debian “penguin” image from Google’s CDN. The image server at images.linuxcontainers.org will be discontinued for LXD users.
Update: May 2024
Canonical added an image server for their users. Add this image server if you want to use other distros without building them yourself.
Introduction
ChromeOS users who have ever opened a terminal have, consciously or not, used LXD. In a nutshell, LXD is used to run Linux in an isolated environment. Sounds a bit like Docker, but it’s cooler! :-)
And also similar to Docker, where you download images from Docker Hub. With LXD you often download the images from images.linuxcontainers.org. The difference with Docker Hub is that the LXD images are built and provided by just two maintainers, with support from Canonical. At least Canonical did support it. And that soon falls on the feet of LXD users, and ChromeOS users in particular. But back to the beginning…
What happended?
Thomas Hipp, one of the main developers of LXD, left Canonical in November 2023. As a result, Canonical withdrew all funding for the images.linuxcontainers.org image server. The costs are currently unsustainable. Access to images.linuxcontainers.org will be phased out over a transition period. This was announced in a blog post by Stéphane Graber, one of the main maintainers of LXD, in mid-December 2023, including specific deadlines.
What is also brand new is that Canonical has decided to change the LXD licence from Apache2 to AGPLv3 with just one commit. They are also forcing all contributions to sign the Canonical CLA. This is a bad idea.
The Canonical image mirror sites (UK, US) were last updated in August 2023 and only offer ubuntu: and ubuntu-daily: images.
The ChromeOS issue
Pffiffy foxes may wonder what about the Debian image, which is called penguin in ChromeOS. This image is not obtained from the public image server, but is built and published by a private Google CDN. These images are not affected by the shutdown of the image server. An introduction to the differences between “Vanilla Debian” and the ChromeOS image was given in the blog post A closer look at Chrome OS using LXD to run Linux GUI apps by Simos Xenitellis.
The problem becomes concrete if you want to use an image that is not the provided Debian or Canonical’s Ubuntu. For example, if you want to test a package for other Linux distros, need an Alpine Linux container, open a Kali container or want to play with Busybox.
ChromeOS actually has the images.linuxcontainers.org image server in its remote list, checkable via crosh:
(termina) chronos@localhost ~ $ lxc remote list
+-----------------+------------------------------------------+---------------+-------------+--------+--------+--------+
| NAME | URL | PROTOCOL | AUTH TYPE | PUBLIC | STATIC | GLOBAL |
+-----------------+------------------------------------------+---------------+-------------+--------+--------+--------+
| images | https://images.linuxcontainers.org | simplestreams | none | YES | NO | NO |
+-----------------+------------------------------------------+---------------+-------------+--------+--------+--------+
| local (current) | unix:// | lxd | file access | NO | YES | NO |
+-----------------+------------------------------------------+---------------+-------------+--------+--------+--------+
| ubuntu | https://cloud-images.ubuntu.com/releases | simplestreams | none | YES | YES | NO |
+-----------------+------------------------------------------+---------------+-------------+--------+--------+--------+
| ubuntu-daily | https://cloud-images.ubuntu.com/daily | simplestreams | none | YES | YES | NO |
+-----------------+------------------------------------------+---------------+-------------+--------+--------+--------+
Until mid-April you will still be able to download your images. What happens after that is still unclear at the moment.
Google is known for not using AGPL licensed software in its products. The reasons differ from the topic of this article, but a similar situation is known for example from Apple with their bash version. At the moment it looks as if ChromeOS will be able to upgrade to LXD version 5.20 and then we users will have a problem that has no foreseeable solution at the moment.
The Incus hard fork
As a result of Canonical’s sudden licence change and the associated CLA, LXD unfortunately had to undergo a hard fork under duress called Incus.
Incus cleaned up the code base and removed rarely used features and all the snap-depended code. Incus does not try to stay compatible with LXD.
Incus user will still be able to download images from images.linuxcontainers.org in the future.
Workarounds for the future
LXD allows using nested containers. This feature can be enable using the security.nesting flag which is already enabled in the default penguin container.
(termina) chronos@localhost ~ $ lxc profile show default | grep security.nesting
security.nesting: "true"
This means that it is already possible to use Incus or Docker inside of LXD. Also, you can use QEMU.
It is also possible to build your own LXD images using distrobuilder.
The ideal solution
Unfortunately, it is not possible to replace LXD with Incus under ChromeOS without going into developer mode.
It would be great if Google would provide other images besides Debian. If not via a public image server, then perhaps via their CDN.