Flatpak

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From the project README: "Flatpak is a system for building, distributing and running sandboxed desktop applications on Linux."

From flatpak(1):

Flatpak is a tool for managing applications and the runtimes they use. In the Flatpak model, applications can be built and distributed independently from the host system they are used on, and they are isolated from the host system ('sandboxed') to some degree, at runtime.

Flatpak uses OSTree to distribute and deploy data. The repositories it uses are OSTree repositories and can be manipulated with the ostree utility. Installed runtimes and applications are OSTree checkouts.

Installation

Install the flatpak package.

Note: If you want to build flatpaks with flatpak-builder you will need to install the optional dependencies of elfutils and patch.

Managing repositories

Note: By default, every flatpak command works system-wide, i.e. packages are installed for all users in the computer and flatpak requires the user to supply root's password. To install packages and work with repositories on a single user (with no need of superuser rights) you can add the option --user to each command. If you want, for example, to add a repository only visible to you, you should run $ flatpak remote-add --user name location. To install a package visible only to you, run $ flatpak install --user package-name.

Add a repository

To add a remote flatpak repository do:

$ flatpak remote-add name location

where name is the name for the new remote, and location is the path or URL for the repository.

For example to add the official Flathub repository:

$ flatpak remote-add --if-not-exists flathub https://dl.flathub.org/repo/flathub.flatpakrepo

Delete a repository

To delete a remote flatpak repository do:

$ flatpak remote-delete name

where name is the name of the remote repository to be deleted.

List repositories

To list all the added repositories do:

$ flatpak remotes

Managing runtimes and applications

Search for a remote runtime or application

Before being able to search for a runtime or application in a newly added remote repository, we need to retrieve the appstream data for it:

$ flatpak update

Looking for updates...
Updating appstream data for remote name

Then we can proceed to search for a package with flatpak search packagename, e.g. to look for the package libreoffice with the flathub remote configured:

$ flatpak search libreoffice

Application ID              Version Branch Remotes Description                       
org.libreoffice.LibreOffice         stable flathub The LibreOffice productivity suite

List all available runtimes and applications

To list all available runtimes and applications in a remote repository named remote do:

$ flatpak remote-ls remote

Install a runtime or application

To install a runtime or application do:

$ flatpak install remote name

where remote is the name of the remote repository, and name is the name of the application or runtime to install.

Tip: You can use partial identifiers flatpak install partial-name (for example flatpak install libreoffice).

List installed runtimes and applications

To list installed runtimes and applications do:

$ flatpak list

Run applications

Binaries are available in /var/lib/flatpak/exports/bin, which is automatically added to $PATH by /etc/profile.d/flatpak-bindir.sh. You may have to re-login to apply the change.

Flatpak applications can also be run with the command line:

$ flatpak run name

Update a runtime or application

To update a runtime or application named name do:

$ flatpak update name

Uninstall a runtime or application

To uninstall a runtime or application named name do:

$ flatpak uninstall name

Tip: You can uninstall unused flatpak "refs" (aka orphans with no application/runtime) with flatpak uninstall --unused.

Adding Flatpak .desktop files to your menu

Flatpak expects window managers to respect the XDG_DATA_DIRS environment variable to discover applications. This variable is set by the script /etc/profile.d/flatpak.sh. Updating the environment may require restarting the session. If the launcher does not support XDG_DATA_DIRS, you can edit the list of directories scanned and add these to it:

~/.local/share/flatpak/exports/share/applications
/var/lib/flatpak/exports/share/applications

This is known to be necessary in Awesome.

Note: The script will not work if the default shell is set to Fish. You can fix this by using the work-around in a comment on fish-shell issue 7485.

Viewing sandbox permissions of application

Flatpak applications come with predefined sandbox rules which define the resources and file system paths the application is allowed to access. To view the specific application permissions do:

$ flatpak info --show-permissions name

The reference of the sandbox permission names can be found on official flatpak documentation.

Overriding sandbox permissions of applications

If you find the predefined permissions of the application too lax or too restrictive you can change to anything you want using flatpak override command. For example:

flatpak override --nofilesystem=home name

This will prevent the application access to your home folder.

Every type of permission, such as device, filesystem or socket, has a command line option that allows that particular permission and a separate option that denies permission. For example, in case of device access --device=device_name allows access, --nodevice=device_name denies the permission to access device.

For all permission types commands consult the manual page: flatpak-override(1)

Permission overrides can be reset to defaults with command:

$ flatpak override --reset name

Flatseal is a GUI permissions manager which offers simple point-and-click permissions operations.

Creating a custom base runtime

This article or section needs expansion.

Reason: This can certainly be improved. It also has problems with D-Bus for GNOME apps. (Discuss in Talk:Flatpak)

Warning: If you want to release your software to the public as a Flatpak, an Arch-based runtime is unsuitable. In this case, you will want to follow official documentation to integrate your software into the proper Flatpak ecosystem using the common runtimes.

Note:

You may want to use an untrusted, unprivileged user account for bundling untrusted software because the software is not sandboxed during app and runtime creation.
When distributing bundles to others, you may be legally obliged to provide the source code of some of the bundled software upon request. You may want to use ABS to build these packages from source.

You can create a custom Arch-based base runtime and base SDK for Flatpak using pacman. You can then use it for building and packaging applications. This is an alternative for personal use to the default org.freedesktop.BasePlatform and org.freedesktop.BaseSdk runtimes.

In addition to flatpak, you need to have installed fakeroot and for pacman hooks support also fakechroot.

First, start by creating a directory for building the runtime and possibly applications.

$ mkdir myflatpakbuilddir
$ cd myflatpakbuilddir

You can then prepare a directory for building the runtime base platform. The files subdirectory will contain what will later be the /usr directory in the sandbox. Therefore you will need to create symbolic links so the default /usr/share etc. from Arch can still be accessed at the usual path.

$ mkdir -p myruntime/files/var/lib/pacman
$ touch myruntime/files/.ref
$ ln -s /usr/usr/share myruntime/files/share
$ ln -s /usr/usr/include myruntime/files/include
$ ln -s /usr/usr/local myruntime/files/local

Make your host OS fonts available to the Arch runtime:

$ mkdir -p myruntime/files/usr/share/fonts
$ ln -s /run/host/fonts myruntime/files/usr/share/fonts/flatpakhostfonts

You need and may want to adapt your pacman.conf before installing packages to the runtime. Copy /etc/pacman.conf to your build directory and then make the following changes:

Remove the CheckSpace option so pacman will not complain about errors finding the root filesystem for checking disk space.
Remove any undesired custom repositories and IgnorePkg, IgnoreGroup, NoUpgrade and NoExtract settings that are needed only for the host system.

Now install the packages for the runtime.

$ fakechroot fakeroot pacman -Syu --root myruntime/files --dbpath myruntime/files/var/lib/pacman --config pacman.conf base
$ mv pacman.conf myruntime/files/etc/pacman.conf

Set up the locales to be used by editing myruntime/files/etc/locale.gen. Then regenerate the runtime’s locales.

$ fakechroot chroot myruntime/files locale-gen

The base SDK can be created from the base runtime with added applications needed for building packages and running pacman.

$ cp -r myruntime mysdk
$ fakechroot fakeroot pacman -S --root mysdk/files --dbpath mysdk/files/var/lib/pacman --config mysdk/files/etc/pacman.conf base-devel fakeroot fakechroot --needed

Insert metadata about runtime and SDK.

myruntime/metadata

[Runtime]
name=org.mydomain.BasePlatform
runtime=org.mydomain.BasePlatform/x86_64/2016-06-26
sdk=org.mydomain.BaseSdk/x86_64/2016-06-26

mysdk/metadata

[Runtime]
name=org.mydomain.BaseSdk
runtime=org.mydomain.BasePlatform/x86_64/2016-06-26
sdk=org.mydomain.BaseSdk/x86_64/2016-06-26

Add base runtime and SDK to a local repository in the current directory. You may want to give them appropriate commit messages such as “My Arch base runtime” and “My Arch base SDK”.

$ ostree init --mode archive-z2 --repo=.
$ EDITOR="nano -w" ostree commit -b runtime/org.mydomain.BasePlatform/x86_64/2016-06-26 --tree=dir=myruntime
$ EDITOR="nano -w" ostree commit -b runtime/org.mydomain.BaseSdk/x86_64/2016-06-26 --tree=dir=mysdk
$ ostree summary -u

Install the runtime and SDK.

$ flatpak remote-add --user --no-gpg-verify myarchos file://$(pwd)
$ flatpak install --user myarchos org.mydomain.BasePlatform 2016-06-26
$ flatpak install --user myarchos org.mydomain.BaseSdk 2016-06-26

Creating apps with pacman

As an alternative to building applications the usual way, we can use pacman to create a containerized version of the regular Arch packages. Note that /usr is read-only when creating apps, so we can not use Arch’s packages when building an app. To create a real app with pacman, we can either

use pacman to create a runtime containing all dependencies
and compile the app ourselves as usual or perhaps using pacman with a custom PKGBUILD tailored to Flatpak which uses --prefix=/app for the configure script,

or we can

use pacman to create a runtime containing the app installed with pacman
and create a dummy app to launch it.

For doing the latter, first create a runtime using pacman such as this one for gedit. The runtime is first initialized and prepared for use with pacman.

$ flatpak build-init -w geditruntime org.mydomain.geditruntime org.mydomain.BaseSdk org.mydomain.BasePlatform 2016-06-26
$ flatpak build geditruntime sed -i "s/^#Server/Server/g" /etc/pacman.d/mirrorlist
$ flatpak build geditruntime ln -s /usr/var/lib /var/lib
$ flatpak build geditruntime fakeroot pacman-key --init
$ flatpak build geditruntime fakeroot pacman-key --populate archlinux

Then the package is installed. The host’s network connection must be made available to pacman.

$ flatpak build --share=network geditruntime fakechroot fakeroot pacman --root /usr -S gedit

You can test the installation before finishing the runtime (without proper sandboxing).

$ flatpak build --socket=x11 geditruntime gedit

Now finish building the runtime and export it to a new local repository. pacman’s GnuPG keys have permissions that may interfere and need to be removed first.

$ flatpak build geditruntime rm -r /etc/pacman.d/gnupg
$ flatpak build-finish geditruntime
$ sed -i "s/\[Application\]/\[Runtime\]/;s/runtime=org.mydomain.BasePlatform/runtime=org.mydomain.geditruntime/" geditruntime/metadata
$ flatpak build-export -r geditrepo geditruntime

Then create a dummy app.

$ flatpak build-init geditapp org.gnome.gedit org.mydomain.BaseSdk org.mydomain.geditruntime

Now finish the dummy app. You can fine-tune the app’s access permissions when sandboxed by giving additional options when finishing the build. For possible options see the Flatpak documentation and the GNOME manifest files. Alternatively, adapt geditapp/metadata to your needs after finishing the build but before exporting. When the metadata file is complete, export the app to the repository.

$ flatpak build-finish geditapp --socket=x11 [possibly other options] --command=gedit
$ flatpak build-export geditrepo geditapp

Install it along with the runtime.

$ flatpak --user remote-add --no-gpg-verify geditrepo geditrepo
$ flatpak install --user geditrepo org.mydomain.geditruntime
$ flatpak install --user geditrepo org.gnome.gedit
$ flatpak run org.gnome.gedit