Silverblue is designed to be easy and straightforward to use, and specialist knowledge should generally not be required. However, Silverblue is built differently from other operating systems, and there are therefore some things that it is useful to know.
Silverblue has different options for installing software, compared with a standard Fedora Workstation (or other package-based Linux distributions). These include:
Flatpak apps: this is the primary way that (GUI) apps get installed on Silverblue.
Toolbox: Used primarily for CLI apps; development, debugging tools etc.
Package layering: The rpm-ostree tool used for host updates is a full hybrid image/package system. By default the system operates in pure image mode, but package layering is useful for things like libvirt, drivers, etc.
See the dedicated toolbox page to get started with it.
Flatpak is the primary way that apps can be installed on Silverblue. (For information, see flatpak.org.) Flatpak works out of the box in Fedora Silverblue, and Fedora provides a small (but growing) collection of apps that can be installed.
The other main source of Flatpak apps is Flathub, which provides a large repository of Flatpak apps that can be installed.
To setup Flathub on Fedora Silverblue, open the Flathub setup page for Fedora and click the “Flathub repository file” button to download the Flathub configuration.
A popup window will show a download option for the file. The “Open with” option should show “Software Install (default)”. Click on the “OK” button to start the download.
After the download is complete, a new window will open showing the Flathub repository. This window also shows the source location of the repository to be installed, under the details heading (1). To start the installation of the Flathub repository, click on the “Install” button (2).
After the repository installation process is complete, the window will be updated to show a “Remove" button in place of the “Install” button.
Once the Flathub repository has been setup, it can be used to install Flatpak apps. This can be done directly from the Software app, or apps can be browsed on the Flathub website.
If you choose to install apps from the Flathub website, clicking "Install" will download a file which will be opened by the Software app, which can then be used to install the app. For example, to install LibreOffice, you first search for and open the LibreOffice page, and then press the “Install” button (2).
After clicking the “Install” button, a download information window will be shown. Verify the correct Flatpak has been downloaded and then click on the “OK” button to begin installing the LibreOffice application.
Once the Flatpak is downloaded, the Software application will open a new window with an “Install” button (2). Click this button to begin installation.
In addition to using the Software app to install Flatpak apps, it is also possible to use the
flatpak command line interface. See the Flatpak documentation for how to do this.
Package layering works by modifying your Silverblue installation. As the name implies, it works by extending the packages from which Silverblue is composed.
Good examples of packages to be layered would be:
fish: An alternative Unix shell
sway: A Wayland tiling compositor
libvirt: The libvirt daemon
Most (but not all) RPM packages provided by Fedora can be installed on Silverblue using this method.
Currently, using package layering creates a new "deployment", or bootable filesystem root. It does not affect your current root. This preserves rollback and the transactional model, but means that the system must be rebooted after a package has been layered. If you don’t want to reboot your system for switching to the new deployment, you can use an experimental
rpm-ostree ex apply-live command to update the filesystem to see changes from new deployment, but it’s generally expected that you use package layering sparingly, and use
dnf install inside a
Package layering is generally done from the command line. However, the Software application does rely on it for installing a small number of apps that are currently difficult to install as Flatpaks.
Packages can be installed on Silverblue using:
$ rpm-ostree install <package name>
This will download the package and any required dependencies, and recompose your Silverblue image with them.
rpm-ostree uses standard Fedora package names, which can be searched using DNF (this is not available on a Silverblue host, but can be used in a toolbox).
Once a package has been installed in this manner, it will be kept up-to-date as new versions are released and as the base operating system is updated.
In some scenarios, you may want to test out a new version of
kernel or other packages that live on the host. The
rpm-ostree override command can be used to replace a package with a different version. You can download the package locally and run:
$ rpm-ostree override replace <path to package>
Or you can override packages without downloading using links from koji or bodhi. For example:
$ rpm-ostree override replace https://kojipkgs.fedoraproject.org//packages/podman/3.1.2/1.fc34/x86_64/podman-3.1.2-1.fc34.x86_64.rpm https://kojipkgs.fedoraproject.org//packages/podman/3.1.2/1.fc34/x86_64/podman-plugins-3.1.2-1.fc34.x86_64.rpm
You may also use
override remove to effectively "hide" packages; they will still exist in the underlying base layer, but will not appear in the booted root.
Removing and replacing packages using package layering is not generally recommended. For more information, see the rpm-ostree documentation.