What does it mean for a Linux distribution to be “fresh”?

I recently had a discussion with LuboŇ° Kocman of openSUSE about how distros can monitor their “freshness”. In other words: how close is a distro to upstream? From our perspectives, it’s helpful to know which packages are significantly behind their upstreams. These packages represent areas that might need attention, whether that be a gentle nudge to the maintainer or recruiting additional volunteers from the community.

The challenge is that freshness can mean different things. The Repology project monitors a large number of distributions and upstreams to report on the status. But simply comparing the upstream version number to the packaged version number ignores a lot of very important context.

Updating to the latest upstream version as soon as it comes out is the most obvious definition of “fresh”, but it’s not always the best. Rolling releases (and their users) probably want that. In Fedora, policy is to not do “major updates” within a release. Many other release-oriented distributions have a similar policy, with varying degrees of “major”. Enterprise distributions add another wrinkle: they’ll backport security fixes (and sometimes key features), so the difference in version number doesn’t necessarily tell you what’s missing.

Of course, the upstream’s version number doesn’t necessarily tell you much. Semantic versioning is great, but not everyone uses it. And not everyone that uses it uses it well. If a distribution has version 1.4 and upstream released 1.5, is that a lack of freshness or an intentional decision to avoid mid-release compatibility changes?

I don’t have a good answer. This is a hard problem to solve. Something like Repology may be the best we can do with reasonable effort. But I’d love to have a more accurate view of how fresh Fedora packages are within the bounds of policy.

Linux distros should be opinionated

Last week, the upstream project for a package I maintain was discussing whether or not to enable autosave in the default configuration. I said if the project doesn’t, I may consider making that the default in the Fedora package. Another commenter said “is it a good idea to have different default settings per packaging ? (ubuntu/fedora/windows)”

My take? Absolutely yes. As I said in the post on “rolling stable” distros, a Linux distribution is more than an assortment of packages; it is a cohesive whole. This necessarily requires changes to upstream defaults.

Changes to enable a functional, cohesive whole are necessary, of course. But there’s more than “it works”, there’s “it works the way we think it should.” A Linux distribution targets a certain audience (or audiences). Distribution maintainers have to make choices to make the distro meet that audience’s needs. They are not mindless build systems.

Of course, opinions do have a cost. If a particular piece of software works differently from one distro to another, users get confused. Documentation may be wrong, sometimes harmfully so. Upstream developers may have trouble debugging issues if they are not familiar with the distro’s changes.

Thus, opinions should be implemented judiciously. But when a maintainer has given a change due thought, they should make it.

What do “rolling release” and “stable” mean in the context of operating systems?

In a recent post on his blog, Chris Siebenmann wrote about his experience with Fedora upgrades and how, because of some of the non-standard things he does, upgrades are painful for him. At the end, he said “What I really want is a rolling release of ‘stable’ Fedora, with no big bangs of major releases, but this will probably never exist.”

I’m sympathetic to that position. Despite the fact that developers have worked to improve the ease of upgrades over the years, they are inherently risky. But what would a stable rolling release look like?

“Arch!” you say. That’s not wrong, but it also misses the point. What people generally want is new stuff so long as it doesn’t cause surprise. Rolling releases don’t prevent that, they spread it out. With Fedora’s policy, for example, major changes (should) happen as the release is being developed. Once it’s out, you get bugfixes and minor enhancements, but no big changes. You get the stability.

On the other hand, you can run Fedora Rawhide, which gets you the new stuff as soon as it’s available, but you don’t know when the big changes will come. And sometimes, the changes (big and little) are broken. It can be nice because you get the newness quickly. And the major changes (in theory) don’t all come at once.

Rate of change versus total change

For some people, it’s the distribution of change, not the total amount of change that makes rolling releases compelling. And in most cases, the changes aren’t that dramatic. When updates are loosely-coupled or totally independent, the timing doesn’t matter. The average user won’t even notice the vast majority of them.

But what happens when a really monumental change comes in? Switching the init system, for example, is kind of a big deal. In this case, you generally want the integration that most distributions provide. It’s not just that you get an assortment of packages from your distribution, it’s that you get a set of packages that work together. This is a fundamental feature for a Linux distribution (excepting those where do-it-yourself is the point).

Applying it to Fedora

An alternate phrasing of what I understand Chris to want is “release-quality packages made available when they’re ready, not on the release schedule.” That’s perfectly reasonable. And in general, that’s what Fedora wants Rawhide to be. It’s something we’re working on, particularly with the ability to gate Rawhide updates.

But part of why we have defined releases is to ensure the desired stability. The QA team and other testers put a lot of effort into automated and manual tests of releases. It’s hard to test against the release criteria when the target keeps shifting. It’s hard to make the distribution a cohesive whole instead of a collection of packages.

What Chris asks for isn’t wrong or unreasonable. But it’s also a difficult task to undertake and sustain. This is one area where ostree-based variants like Fedora CoreOS (for servers/cloud), Silverblue (for desktops), and IoT (for edge devices) bring a lot benefit. The big changes can be easily rolled back if there are problems.