SOFTWARE

Linux app packaging rethink could leave alternative-init distros in the cold

Flatpak development has been very quiet for years. Discussions about a next-generation take are happening – and some of the signs are worrying if, like many FOSS folks, you are systemd-intolerant.

In the course of researching our article on MX Linux 25.2, we came across an interesting Reddit discussion from last month, which in turn led us to a Flatpak development blog post from late last year.

It looks like a team is collecting ideas for what is currently called "Flatpak-NG" – as in next generation. If this solidifies into code, this may form the basis of Flatpak version 2.

The blog post isn't very informative, but the Reddit thread links to the video of a presentation from last month's Linux App Summit in Berlin, which spells things out more clearly.

The Flatpak-NG idea involves handing off a lot of the isolation in Flatpak from the current bubblewrap layer to an as-yet-unwritten systemd component that the developers are currently calling systemd-appd. This would considerably simplify Flatpak, and enable it to do more isolation, including virtualizing the network stack – but at the price of making Flatpak 2 depend on systemd. A developer who was at the talk, Jorge Castro, later explained and confirmed this in a Fediverse thread.

The teams behind other init systems could, of course, write their own replacement for the notional systemd-appd, but that would be a substantial amount of work. The tool that provides the new init-switching functionality in MX Linux 25.1 and 25.2, init-diversity, currently supports six other init systems besides systemd, and we've seen little sign of them cooperating to create an alternative to systemd that provides even a subset of its wider functionality.

Flatpak is widely used and supported. Not all distros include it by default, but it's the only widely adopted alternative to Canonical's Snap packaging system.

Snap is more versatile: it works fine with shell programs, and even the kernel can be packaged as a Snap, which is how Ubuntu Core handles it. Snap's implementation is much simpler and cleaner than Flatpak's, as is the distribution model – which, as we've reported before, is entirely open source. The only proprietary part is Canonical's Snap Store website. The trouble is, the louder advocates in the peanut gallery rarely even think about things like implementation details; they just get upset about more visible things that are easier to understand – such as who owns a website.

There are other alternatives out there, such as AppImage, 0install, AppDir, and GNUstep's implementation of NeXT and Apple's .app format. We have compared these in detail before.

Only two really have wide adoption, though. There's Snap, which Canonical claims has more users simply because Ubuntu has more users than all the other desktop distros put together, and there's Flatpak, which is used by every other distro with any kind of cross-distro package support.

The snag is, if Flatpak 2 does arrive in a year or two, and requires systemd, then that could spell the end of Flatpak support on many systemd-free distros. That includes MX Linux, Alpine Linux, Devuan, Slackware, and many other smaller projects. For many of these, Flatpak is a lifeline: the only way to access much of the wider Linux app market.

It's not so much that the Flatpak-NG team is the "A-Team," but the only team. In the original A-Team, Colonel John "Hannibal" Smith was wont to say "I love it when a plan comes together." We suspect a lot of people will not love it if this plan comes together. ®