Jon Seager, Canonical VP of Engineering, took to Ubuntu Discourse to discuss the company’s Ubuntu Core Desktop, saying the company plans to accelerate development.
Ubuntu Core Desktop is one of the more interesting concepts in the Linux community, a Snap-based Linux distro that could provide users with far more flexibility than current options. Core Desktop is based on Ubuntu Core, which is widely used in IoT, robotics, and other embedded platforms. A developer preview of Core Desktop was initially announced in 2023, but the project went dormant shortly after.
To understand why Core Desktop is an interesting concept, one must first understand the Linux distro landscape.
Stable vs Rolling
Generally speaking, Linux distros fall into two camps: stable release and rolling release.
Stable Release
Stable release distros are often alternately called point-release distros. These distros have distinct version numbers, such as Debian 11, Debian 12, Debian 13, Ubuntu 24.04, Ubuntu 26.04, and so on. When a new version is released, the major components of that distro — as well as the software available in the distro’s software repository — are all frozen at that version. With the exception of security fixes, major bug fixes, and specific apps like web browsers, the major components and available software stay at that version number for the life of that specific release.
For example, Debian 13 comes with LibreOffice 25.2.3 and LibreOffice will remain at version 25.2.3 for the life of Debian 13, only receiving security fixes and major bug fixes. While it is possible to manually install newer versions of software, those newer versions may depend on libraries that the older system base doesn’t have. If the user manually upgrades those, then other applications may not work with the newer libraries.
While the “stable” in a stable release distro refers to the package base not changing — an important requirement for many in the enterprise space — stability, in the sense of reliability, is often an important side effect.
Rolling Release
In contrast, a rolling release distro has no major version numbers or point releases, and no upgrade from one major version to another. Instead, rolling release distros push out new updates to software as it becomes available, rather than waiting 6 months, a year, or longer to push out a new distro version and new accompanying software.
The benefit of a rolling release is that the user always has the latest and greatest software, but often at the expense of some reliability. Rolling release users may have to do a bit more troubleshooting if an errant update breaks their system or their workflow.
Containerized Applications
One major way that Linux distros are trying to solve the issue of stable vs rolling is with containerized apps. The three main options are Flatpak, Snap, and AppImage. The benefit of these app formats is that they bundle their own libraries and dependencies, rather than relying on the system. So a user who wants a stable system can safely have the latest applications via Flatpak, Snap, or AppImage without worrying about introducing incompatibilities. Some so-called “immutable” distros use this approach, making it difficult to modify the underlying system while relying on containerized apps for the userspace.
Of the three, Snap was created by Canonical and is still largely used almost exclusively by Ubuntu-based distros. Outside of Ubuntu, Flatpak is far more popular, with AppImage also having its diehard following. In the case of Snaps and Flatpaks, these applications are also sandboxed, meaning they are isolated from the system, providing a measure of security that traditional apps from a distro’s repository don’t provide.
Snaps were originally very unpopular because of abysmal performance, as well as Canonical retaining control of the Snap Store. In recent years, however, Snaps have closed the performance gap, often rivaling or even surpassing Flatpaks. Similarly, although many users claim Snaps are not open source, that claim is inaccurate. The format itself is open source, with only the Snap Store being closed source and controlled by Canonical.
Another major advantage of Snaps over Flatpaks is the range of applications that can be built as a Snap. Flatpaks are largely limited to desktop apps that have a GUI. In contrast, Snaps can include both desktop and terminal-based apps. Even the Linux kernel can be bundled as a Snap.
Canonical has also improved the simplicity and security of Snaps, in some ways beyond Flatpaks. While Flatpak offers ways to modify an app’s permission to restrict or free up its capabilities, doing so often requires installing a separate app and the user has to know what permissions to enable/disable. In contrast, Canonical has adopted a simple prompt system inspired by iOS and Android, where an app asks on first run if it can have certain permissions, such as access to the microphone or camera.
Ubuntu Core Desktop
Ubuntu Core and Core Desktop are designed to leverage the flexibility of Snaps to solve the issue of stable vs rolling release distros.
With each individual component of the system — kernel, drivers, window manager, desktop environment, and apps — all bundled as self-contained Snaps, a user can run the latest and greatest without worrying about introducing incompatibilities or instabilities.
Seager highlights those benefits in his blog post:
I’ve written previously about “immutable” Linux distributions, what they’re trying to achieve and where the promises are often broken. Ubuntu Core moves to everything as a snap – including the bootloader, the kernel, the desktop environment, userspace daemons and all of your apps. For users, this means a desktop that’s harder to break, easier to recover and more adaptable to different devices and workflows. It also gives users greater control over the data their applications can access.
Seager also acknowledges that the 2023 preview failed to meet its goals:
Our 2023 preview fell short of this vision. While it helped us better understand the problems we’d face, it bundled much of the desktop into a single alternative base snap. Separating those components is one of our top priorities as we restart the project.
The blog post goes on to highlight the benefits to three specific use cases: casual users mainly interested in web browsing, developers, and gamers, although the benefits certainly go far beyond those three groups.
The company’s new approach will have challenges:
There will be many challenges along the way! Most of these stem from the fact that Ubuntu Core requires that all applications/services be packaged as strictly confined snaps. This immediately presents two challenges: making applications compatible with strict confinement, and ensuring sufficient availability of applications on the platform.
Seager goes on to describe the benefits of Canonical’s new approach:
The biggest shortcoming of the 2023 developer preview was its architecture. The system used a modified base snap – swapping core22 for an alternative base snap that contained much of the desktop environment.
This alternate core snap was monolithic: it contained GDM, the GNOME desktop and even Firefox itself in early versions. This approach breaks many of the promises and goals of Ubuntu Core Desktop. It did enable the team to release what looked like a working PoC quickly, and this is what we’ve been working on for the past few weeks.
We want to build a modular desktop architecture that defines clear interfaces between components. Components such as the display manager, desktop environment, multimedia servers, networking and other core capabilities should adhere to well-defined interfaces and remain implementation agnostic.
The result will be a desktop whose constituent parts can evolve independently, without forcing the rebuild of the entire operating system image every time something changes – one of the key differentiators from other immutable operating system implementations.
Conclusion
If Canonical is able to give Core Desktop the attention it deserves, the distro could fundamentally change Ubuntu forever, and possibly the entire Linux space. While Snaps have been one of the more controversial technologies among Linux users, they could finally find their place, and wider acceptance, in Core Desktop.