Flatpak and Snap are universal package formats that provide sandboxed and containerized environments for Linux. Although they have many similarities, they have more differences. Some people think that the problems plaguing Snap also apply to Flatpak, but this is untrue. I have seen many users unintentionally enumerating Snap’s problems, which I believe needs to be addressed.
This post taps into a couple of arguments that users make when they are assuming that Flatpak and Snap suffer the same issues, or the problems are equally bad. Do keep in mind that the quotes below are pseudoquotes, meaning that they are not the exact wording from those users, but from what I have interpreted when discussing with them.
Flatpak applications and snaps take a lot more space because they install more packages and/or don’t have deduplication.
Flatpak definitely takes more disk space than native packages. However, the disk space is not as large as users make it out to be. Sadly, many people see the problem of Snap’s high disk space and assume that Flatpak needs as much as well. Snap uses a lot more space than Flatpak and any other package managers/formats because Snap does not implement deduplication, so data is duplicated. Flatpak, on the other hand, does deduplication with runtimes and baseapps, which are basically the core packages, e.g.
org.gnome.Platform for GTK applications. Instead of duplicating data for runtimes or baseapps when using multiple applications that use the same runtime or baseapp, it only takes once. Essentially, the more applications you install, the more space-efficient Flatpak becomes.
Snaps compress most, if not all data using LZO, so they take up slightly less space than if they were uncompressed. Despite the compression, snaps still take a lot more space for applications than Flatpak applications due to the lack of deduplication. On top of that, LZO wasn’t designed to be space efficient, only performant.
So, Flatpak does not take as much space as Snap, because it deduplicates core libraries, which can save hundreds of megabytes, or even gigabytes of space depending on the amount of applications installed.
The following paragraphs are off-topic and therefore hidden, but I decided to include them because they’re helpful for those that want to make Flatpak more space efficient. You can click on “Click to expand” to expand it. If you’re uninterested, you can skip them and read the rest of the article.
Flatpak doesn't compress data yet, and I don't think it will anytime soon because it doesn't need to, but users who want to make Flatpak more space-efficient can use btrfs compression or other filesystem-level compression.
At the time of writing this article, I have 146 Flatpak packages installed in my user directory, 63 of which are applications. I am using btrfs with zstd:1 (level 1) compression. Here you can see how much disk space a system with this many Flatpak applications would need:
TheEvilSkeleton@TheMainLaptop ~> flatpak list --all | wc -l 146 TheEvilSkeleton@TheMainLaptop ~> flatpak list --app --user | wc -l 63 TheEvilSkeleton@TheMainLaptop ~> sudo compsize -x ~/.local/share/flatpak/ Processed 3548950 files, 199313 regular extents (3128593 refs), 708958 inline. Type Perc Disk Usage Uncompressed Referenced TOTAL 74% 19G 26G 101G none 100% 16G 16G 60G zstd 34% 3.5G 10G 41G
Here you can see that
~/.local/share/flatpak, where Flatpak applications are installed in the user directory, consume about 26G uncompressed, but only 19G when compressed with zstd:1. This is a huge space savings, as it only takes a little more than 70% when it's compressed using zstd:1. If you want to save space when using Flatpak, you can use a filesystem that compresses data.
Flatpak and snaps take a lot longer to launch apps because they have to mount many directories, load more files, set environments, etc.
Theoretical problems don’t always translate into practice. Theoretically, Flatpak slows down startup times: bind mounting directories, setting environments, loading a tiny fraction more of data, etc. add a couple of milliseconds when launching applications. The performance difference between launching a native application and its Flatpak alternative is imperceptible to the eye, except in edge cases like bugs, doing a side by side comparison in slow motion, or when using decade years old hardware. Unlike Snap, Flatpak does not compress applications, and therefore does not spend time decompressing data. Filesystem compression like btrfs compression won’t noticeably hinder performance either, as it is really efficient, optimized and well tested by experienced people, except in edge cases.
As mentioned several times, Snap compresses its data, which noticeably slows down startup time. The differences in startup time are very minor to imperceptible for small programs like command-line interface (CLI) programs, since those applications inherently take very little space, and therefore take very little time to decompress. However, because GUI applications are much larger, take much more space than CLI programs, and are generally more complex, their startup time becomes noticeably slower because Snap must decompress a lot more data.
Briefly put, theoretical problems do not always matter in practice. Flatpak works well on most modern hardware because modern hardware were made to handle complex tasks simultaneously. The speed “deterioration” when starting applications hardly matter to the end user because it’s small enough to not be a problem.
Flatpak and Snap are owned and endorsed by corporations. Red Hat owning the former and Canonical owning the latter.
For clarification purposes, Red Hat holds copyright over most of the source code. However, external contributors and organizations hold copyright over their code contributions, as there is no Contributors License Agreement (CLA). Flatpak is a cross-organizational-distribution effort and developed as part of the freedesktop.org project, whereas Snap is mainly a Canonical effort. Additionally, the “Flatpak®” trademark is owned by GNOME.
Flatpak is endorsed by many organizations, this includes GNOME, Fedora, EndlessOS, KDE, elementaryOS, openSUSE, Red Hat, Collabora and others. And obviously it is endorsed by a large portion of the community too.
Just like systemd and Fedora, Flatpak is politically independent from Red Hat, meaning the maintainers of the project make decisions of their own behalf and not on behalf of Red Hat, while accepting ideas from many people and organizations, therefore it is community-driven by definition.
Since Flatpak and Snap mount a lot of things, they tend to get a lot of loop devices, which bloats the output of
Flatpak does not use loop devices, and therefore does not affect the output of
lsblk. What Flatpak does instead is bind mounts. Bind mounting means to reuse a directory and mount it to another directory. Docker, Podman, Toolbx and other container technologies use bind mounts too.
Snap, on the other hand, literally mounts the image, thus causing it to create loop devices and increase the output of
lsblk per application.
Flatpak and Snap attempt to replace existing package managers.
Flatpak was designed specifically to not replace existing package managers, and it literally cannot. It was only intended to be used for graphical desktop applications and nothing else. Flatpak can be used in server space, but they are severely limited, as they were not designed for CLI programs and cannot run as root. Basically, Flatpak is designed to be an extension for existing distributions, and not a replacement. There cannot be a system with Flatpak only.
Snap, on the other hand, is designed to be a replacement, but it can also be an addition. Ubuntu Core for example is a distribution with Snap only.
In conclusion, many of Snap’s problems do not apply to Flatpak. Many users imply that Flatpak suffers from X problems since Snap suffers from X problems, because they are both universal standards that provide sandboxed and containerized environments.
It is important to understand that while Flatpak and Snap have many similarities, they have many differences. Flatpak was developed for the desktop, whereas Snap was developed for the Internet of Things (IoT), but was later adapted to the desktop. Flatpak works well in many ways and offers more than traditional package managers on the desktop. It takes advantage of modern hardware, just like other complex software like btrfs and systemd, which have theoretical problems just like Flatpak, but fortunately do not appear in practice.
Source file: 2021-10-03-some-people-think-that-the-problems-plaguing-snap-also-apply-to-flatpak-but-this-is-untrue.md