Stratus OS

Stratus OS is the operating system that runs on each Stratus streaming server. It was created in order to streamline the process of provisioning and configuring new servers, and consists of an Arch Linux installation script and several custom Arch packages. This approach to server deployment gives Stratus the convenience of staying fully within the Arch Linux ecosystem while providing complete customizability at a low maintenance cost.

Arch Packages

The Stratus software required by each streaming node is distributed as two Arch packages: stratus-launcher for the Stratus game launcher script and stratusd for the Stratus streaming daemon. Both are available through a custom pacman repository hosted at os.playstratus.io. The stratus-launcher package is small and straight forward. It just installs the Stratus launcher to /usr/bin/stratus-launcher and creates a stratus-launcher-init service that ensures the game environment is automatically initialized before stratusd is started. In contrast, the stratusd package has several parts. Besides installing the stratusd executable to /usr/bin/stratusd, it also

• Initializes the stratusd configuration in /etc/stratusd.conf
• Creates a stratusd user account and adds it to the required groups
• Creates the /var/lib/stratusd/games directory for storing games in
• Inserts a udev rule to allow virtual device creation by non-root users
• Installs the stratusd and stratusd-sway services

These last two systemd services have been carefully designed in order to support running graphical games on an unattended headless system. First, they run as user services instead of system services, meaning that they are launched by systemd under a user session. This is necessary so that systemd initializes a D-Bus message bus session, which most graphical apps depend on. Lingering must also be enabled for the stratusd user so that the services can be started even when the user isn't logged in. The stratusd-sway service starts a headless instance of the Sway Wayland compositor, and is configured as a dependency of the stratusd service. Once Sway has been started, the stratusd service starts the Stratus streaming daemon and sets the WAYLAND_DISPLAY and DISPLAY environment variables appropriately so that it can find Sway's Wayland and XWayland servers, respectively. With this configuration in place, Stratus is able to run games with full support for their usual rendering technologies despite not having an active user session or a connected physical display.

In addition to the stratusd and stratus-launcher packages, Stratus OS would not be complete without a patched fastfetch package that includes the Stratus logo:

Arch Installation Script

The Stratus OS installation script (available at os.playstratus.io/install.sh) is used to install these packages and apply additional system configurations. It is designed to be run from within a live Arch Linux environment, and was inspired by Michael Daffin's personal Arch install script. After prompting the user for basic information (such as the hostname, user account password, and disk to install on), it performs the steps of a standard Arch installation, including disk partitioning, filesystem creation, package installation, and boot loader configuration. If the user didn't specify a password, a secure three-word passphrase is automatically generated using a wordlist. Next, the stratusd and stratus-launcher packages are installed from the custom Stratus repository and configured according to the user's responses to the installer prompts. Finally, the installer also downloads the AppImages for a set of default games.

After a reboot, the server will be ready to accept stream sessions without any additional intervention. The entire installation takes under 5 minutes, and is captured in the Asciinema recording below.

An Asciinema recording of the Stratus OS installer (click to play).