An Immutable OS is a GNU/Linux distribution where the user has limited (if at all!) changes to modify the root filesystem. And by "modify the root filesystem" we mean doing things like installing software with the package manager. Some examples of Immutable OSes that falls in this definition are Fedora Silverblue, openSUSE MicroOS, openSUSE Kubic and EndlessOS. In fact, on Fedora Silverblue, the user can't add software with dnf, not even after becoming "root". Similarly, on openSUSE MicroOS, zypper install just does not work. This brings the advantage of keeping the OS cleaner, consistent, reliable and a lot harder to break. For instance because what developers produce and tests is a lot more similar to what actual users use, with respect to what happens with "traditional OSes". And they usually come with a nice way of rolling back changes too, which is also really valuable.

But what are the technologies behind all that? Well, there are a few, and although the outcome is rather similar, their inner working and characteristics are quite different. In this talk, we will focus on two: ostree and transactional-update. The forme is used in Silverblue and Endless OS, the latter in openSUSE MicroOS and Kubic. We will try to provide a description of how both work and what are the main differences between them.

Even more important: what's the user experience with such distros? And what if one is not only a user, but a developer? Well, this talk will offer a perspective of how it is being to use one as one's own daily driver, for both user-like and developer-like tasks. That would be openSUSE MicroOS. We will cover what it is the current status of the "MicroOS as a Desktop" project, what are the current challenge and the upcoming developments. But we will also try to hint at how the user/developer experience may vary between MicroOS and others (more mature) immutable desktop solutions like Fedora Silverblue and Endless OS.