What is Sirius

Sirius is the installer LuminusOS ships on its live ISO. Unlike a typical distro installer that assumes your hardware will cooperate and only complains when something breaks, Sirius checks first: before it lets you configure anything, it runs a hardware diagnostics pass and tells you up front whether the machine you’re on can actually take an install.

It’s also distro-agnostic. Sirius itself doesn’t know anything about LuminusOS specifically. What OS gets installed, what the disk layout looks like, and how the installer is branded all come from a small config file (distro.toml) any bootc-based distro can ship. See Adapting Sirius to another distro if that’s what brought you here.

For the LuminusOS install flow end-to-end (downloading the ISO, flashing a USB drive, first boot), see the installation guide. This section is a deeper look at how Sirius itself works.

The wizard

Sirius walks you through a fixed set of pages, in an order controlled by /etc/sirius/sirius.toml. The default order is:

1. Welcome
2. Language: every displayable locale on the system, with the common ones pinned up front and the rest following in the same scrollable list; switching languages re-translates the installer live (English and Brazilian Portuguese catalogs ship today)
3. Diagnostics: hardware checks, see Diagnostics
4. Network (auto-hidden if NetworkManager reports no Wi-Fi device)
5. Keyboard: layouts matching your language pinned up front, followed by every other layout in the same scrollable list, with a type-to-test field
6. Timezone: search for a city or click the world map; auto-detected from the running system and shown with a pin on the map
7. Storage: disk and partitioning, see Storage
8. User
9. Summary
10. Progress
11. Finished

Any page in that list can be turned off entirely with a disabled = [...] entry in the same config file. A distro that, say, always uses DHCP and doesn’t need a network page can just disable it.

Privilege model

Sirius’s UI runs as an ordinary, unprivileged process. It never touches disks, partitions, or the bootc image directly. When you confirm the install on the summary page, the UI launches a separate, privileged process (sirius run-playbook) via pkexec, authorized by the polkit action io.sirius.Installer.run-playbook. That privileged process is the only part of Sirius that actually writes to disk.

This split means the GTK4/libadwaita interface you interact with the whole time never runs as root. Only the narrow, scriptable playbook step does, and only after you’ve confirmed you want the install to happen.

Diagnostic-first, not diagnostic-only

Most installers let you configure everything and only discover a blocking problem (not enough RAM, no EFI firmware, whatever) when the install itself fails partway through. Sirius runs its hardware checks as literally the first wizard page, before network, storage, or anything else, so a machine that can’t take the install tells you that immediately, instead of after you’ve spent ten minutes picking disk layouts.

Command line

Outside the wizard, Sirius also has CLI entry points useful for scripting and testing:

• sirius diag: runs the diagnostics checks standalone and prints the results, without launching the GUI.
• sirius --dry-run: walks through the install flow without writing anything to disk, useful for validating a distro.toml/repart.d configuration.