Flatpak Gnome Books

Adopting Flatpak to Reassemble Third Party Applications

January 18, 2017

Solus, like most other Linux based systems, distributes the bulk of its software through binary repositories. To ignore most of the technical details, this is effectively a set of packages, with an address book to look them up (the repository index).

In certain cases, however, we cannot ship some applications. This is invariably due to some kind of licensing restriction, which forbids the redistribution of a package.

For a long time, we’ve made do with the Solus Third Party system. To alleviate the issue of distribution, the system fetches the application directly from the vendor source, and turns it into a native .eopkg locally. This allows you to install the application and manage it through the native package management system.

However… This is not without weakness. It’s long known that the system is far from robust, and while it is indeed integrated into the Software Center, it’s not exactly reliable. Or quick. Additionally, there isn’t even a way to automatically upgrade these ..source.. packages, as they have no native origin.

Clearly, a better approach is needed here.

Flatpak, or Snap?

You read that right. The best approach forward for Solus, for something as desirable yet minor as the Third Party selection, is to use a non-native application management system. Let’s first think about our basic requirements here:

  • Enable us to distribute Google Chrome. This is basically the #1 issue.
  • Minimum disruption with regards to integration. We shouldn’t need to reengineer Solus to make it “fit”.
  • Technically capable
  • Responsive upstream.
  • Simple to integrate into the existing Software Center, to swap out Third Party.

This is a discussion that I’ve been having back and forth for a long time on social networks now, and I decided to put the feelers out one last time. At the time of writing, 66% of 172 voters were in favour of Flatpak.

Brand Power

Clearly, in terms of “brand power”, Snap has the upper hand currently. It’s well known, well publicised, and receives constant coverage in the news. Flatpak, on the other hand, is often percieved as having a slower rate of development, etc. In truth, Flatpak is actually just as quick in terms of development and enjoys very frequent updates. So, let us dismiss the power of the brand, and look at the technical aspects.

Why Flatpak is our choice

Firstly, and very importantly to us, the so-called “chrome distribution issue” has already been conquered by Endless OS, utilizing Flatpak. On the other hand, this is still (to the best of my knowledge) at the prototype stage with Snaps.

OK, let’s not get hung up completely on a single example. From the perspective of integration, Snap (snapd and snapcraft) represents the biggest integration challenge. To correctly and fully integrate it would require modification of the build system (which disables networking by default for security!) to provide a full set of builds for the packages and their dependencies. Additionally, AppArmor (not used by Solus) is also required.

On the other hand, integrating Flatpak into Solus was as trivial as packaging ostree and flatpak, barring some minor changes which we’re already upstreaming.

You may rightly argue that I’m being lazy. To counter those points, we must look to the future uses of Flatpak within Solus.

The ABI problem (We’ve been here before.)

In a nutshell, a Snap makes use of Ubuntu libraries to provide elements of the runtime. With the recent rise of traditional modes for Snap builds, we’re looking at relocating Ubuntu/Debian files to Solus and expecting them to work. Even with “full” isolation, this still remains an issue. As the creator of Linux Steam Integration, we are painfully aware of the shortcomings of this approach.

On the other hand, Flatpak does use full runtimes (though this can be disabled, which may be useful for the Chrome problem), and does seek to resolve the ABI problems, not just the relocatable package problem. After speaking with Alexander Larsson, I’m confident that we can utilize Flatpak to further improve our Steam runtime in future. Essentially, Solus would host a solus-gaming runtime, built specifically for Steam compatibility, without risking host mangling or having to compromise. This is an area where we can readily put the Solus machinery to work to providing the best possible experience.

Upstream engagement

As previously stated, I’ve put this matter to the Internet a number of times over a fair period of time. However, the only times I’ve been engaged on a technical level from either camp, have always come from Flatpak. I’d like to personally thank Alexander Larsson of Red Hat, the chief developer of Flatpak, for the enthusiasm, honesty, and technical discussions we’ve had on these issues.

While I do not expect developers from either camp to step forward and have these discussions, it certainly does wonders for confidence. This is an upstream I certainly feel comfortable working with, and is clearly passionate about their software.


Well, enough babbling from me. You get the picture, we’re going with Flatpak. It’s a great solution, and in terms of the future, the most suitable route we can take. There is a responsive, engaging community, and it ticks all the boxes for what we want.

Additionally, Flatpak supports AppStream, which Solus already makes use of, so it’s an instant fit in terms of integration into our Software Center.

I look forward to getting some feedback on our integration of Flatpak into Solus, addressing the elephants in the room such as theme integration, and empowering Solus users to choose the software they want.

Remember, we’ll always look initially for integration into the Solus repositories natively first. This way we can ensure we always provide a first class experience. Going forward, Flatpak will replace our use of Third Party entirely, and we will be hosting a public flatpak repository which will grow and blossom over time.