Flatpak

Flatpak is a Linux application sandboxing and distribution framework.

This article extends the documentation in the NixOS manual.

Installation

Global

Using this configuration, flatpak will be installed and ready to use globally for all users:

❄︎ /etc/nixos/configuration.nix

services.flatpak.enable = true;

Per-User

If you'd rather make Flatpak available to a specific user, add flatpak to that user's packages

❄︎ /etc/nixos/configuration.nix

users.users."user" = {
    packages = with pkgs; [
      flatpak
    ];
  };

Window Managers / Compositors Patches

After adding the desired solution to your configuration file, Flatpak will be installed, but it is not always added to your path directly, e.g. when you are using Sway.

To manually add it to the path while using the Greetd login manager and Sway, create a .profile file with an override for your XDG_DATA_DIRS path, e.g.:

≡︎ .profile

export XDG_DATA_DIRS=$XDG_DATA_DIRS:/usr/share:/var/lib/flatpak/exports/share:$HOME/.local/share/flatpak/exports/share

This is also required when installing flatpak on a per-user basis.

Usage

Declarative

To manage Flatpak declaratively, you can either use nix-flatpak or declarative-flatpak

In the event of a Nix rollback, both modules will reinstall the previously declared Flatpak packages

nix-flatpak

A convergent approach to Flatpak management where refs are managed in place

Flatpak packages are not cached in the Nix store

It supports flakes or home-manager, but doesn't support non-flakes only

For more details, see nix-flatpak/discussions/168

A congruent approach to Flatpak management where changes are designed to be atomic, ensuring that either they succeed or nothing happens. This module uses a temporary installation and then overwrites the current one.

It supports non-flake, flakes, and home-manager

For more details, see declarative-flatpak/issues/44

Imperative

Terminal User Interface

To manage Flatpak imperatively, you can use the flatpak command (flatpak Command Reference Documentation)

Example

$ flatpak remote-add --if-not-exists flathub https://dl.flathub.org/repo/flathub.flatpakrepo
$ flatpak update
$ flatpak search Flatseal
$ flatpak install flathub com.github.tchx84.Flatseal
$ flatpak run com.github.tchx84.Flatseal

Graphical User Interface

To install Flatpaks graphically, you can use the GNOME Software Application (gnome-software in nixpkgs)

Note: installing Flatpaks through it is imperative

Configure Repositories Globally

⚠︎

Warning: This assumes you are not installing Flatpak packages declaratively (using nix-flatpak or declarative-flatpak)

Otherwise, the following section could conflict with them

If you are, prefer using nix-flatpak's services.flatpak.remotes or declarative-flatpak's services.flatpak.remotes instead

To automatically configure Flatpak repositories for all users, one can add this snippet to configuration.nix:

❄︎ /etc/nixos/configuration.nix

systemd.services.flatpak-repo = {
    wantedBy = [ "multi-user.target" ];
    path = [ pkgs.flatpak ];
    script = ''
      flatpak remote-add --if-not-exists flathub https://dl.flathub.org/repo/flathub.flatpakrepo
    '';
  };

Development

Build a Flatpak project

The following example builds a demo app of the libadwaita repository using flatpak-builder, installs it locally in the user space and runs it. First install flatpak and flatpak-builder on your system

❄︎ /etc/nixos/configuration.nix

services.flatpak.enable = true;
environment.systemPackages = [
  pkgs.flatpak-builder
];

Clone, build and run the example project.

$ flatpak remote-add --if-not-exists gnome-nightly https://nightly.gnome.org/gnome-nightly.flatpakrepo
$ flatpak install gnome-nightly org.gnome.Sdk org.gnome.Platform
$ git clone https://gitlab.gnome.org/GNOME/libadwaita.git
$ cd libadwaita
$ nix shell nixpkgs#appstream
$ flatpak-builder --disable-tests --user --install build demo/org.gnome.Adwaita1.Demo.json
$ flatpak run org.gnome.Adwaita1.Demo.json

Note that the gnome-nightly repository and the appstream dependency are especially required for this specific project and might be different for other Flatpak projects.

Tips and tricks

Emulate Flatpaks of different architecture

It is possible to install and run Flatpaks which were compiled for a different platform.

In this example we imperatively install the application "Metronome" aarch64 Flatpak package and run it (regardless of the architecture of the host, but in that case, it was x86_64):

$ flatpak install flathub com.adrienplazas.Metronome --arch=aarch64
$ flatpak run com.adrienplazas.Metronome

To support emulation with Qemu, following Binfmt configuration is required.

Troubleshooting

Missing themes and cursors

If you have issues with cursors or themes in general, take a look at Fonts#Flatpak_applications_can't_find_system_fonts