Nix and sway-home

The rest of the desktop is user’s, installed by user. user has no SSH key and no sudo, so get a shell as user from your admin session – a full login, with user’s own systemd user manager and session bus:

sudo machinectl shell user@

Not sudo -iu user: that gives a shell without a session bus, and Home Manager’s step that writes GNOME settings (dark mode, here) then starts a D-Bus daemon of its own from Nix, which looks for its configuration in /etc/dbus-1/ – where NixOS keeps it and Arch does not – and fails. Logged in at tuigreet, user has a bus already.

Then clone sway-home and let Home Manager install it:

git clone https://github.com/EnigmaCurry/sway-home ~/git/vendor/enigmacurry/sway-home
cd ~/git/vendor/enigmacurry/sway-home
just hm-install

hm-install asks for the name and email address to put in git’s configuration, then builds the Home Manager configuration in home-manager/ and switches to it: the packages land in the Nix store, and ~/.config, ~/bin, ~/.bashrc and the rest become links into it. Dotfiles already in the way are renamed to *.backup. The first run downloads a great deal; later ones only what changed.

From then on, as user:

Programs from Nix are updated the Nix way, not by pacman: admin upgrade moves sway, greetd and the rest of the system forward, while firefox, foot, emacs and everything else in sway-home move when its flake.lock does – hm-update then hm-switch, or hm-pull to take the lock sway-home’s repository has. Each switch is a new generation, so hm-rollback undoes one.

sway-home’s own HOME_MANAGER.md describes the rest. This is the user’s half of the “two halves” in the chapter introduction: admin keeps the system in step with ~admin/arch, and Home Manager keeps user’s environment in step with sway-home, each with its own history and its own way back.

GPU drivers for programs from Nix

Programs from Nix are linked against Nix’s own copy of Mesa, which cannot load the drivers Arch installed: without help, firefox and anything else that draws with OpenGL or Vulkan falls back to the CPU. Home Manager’s answer for non-NixOS systems is targets.genericLinux, which sway-home turns on outside NixOS: it builds the GPU drivers from Nix, to match, and asks for one command to be run as root to link them into place as /run/opengl-driver. user has no sudo, so admin runs it, from user’s profile:

sudo /home/user/.nix-profile/bin/non-nixos-gpu-setup

It installs a link in /etc/tmpfiles.d, so that the drivers are linked again at every boot. Run it once more whenever hm-switch says the drivers changed. The link points into the Nix store and moves with every update, so setup seeds 90-ignore.sh with a line that has aconfmgr leave it alone. (A host repo seeded before that needs the line added: IgnorePath '/etc/tmpfiles.d/non-nixos-gpu.conf'.)

Log in

Log out of the user shell, and at the machine itself, log in as user at tuigreet. It starts sway, with sway-home’s configuration.

Networking

This machine does not run NetworkManager – it uses systemd-networkd and iwd, as the install set up – so sway-home leaves out nm-applet, the NetworkManager tray icon: it installs it only where NetworkManager.service exists. For WiFi, iwctl does the same job from a terminal. If you would rather have NetworkManager, the host page shows how to switch the host repo over to it; run hm-switch afterwards and the applet comes back.