nixos-installer/lib/setup-scripts

Host Setup Scripts

This is a library of bash functions, mostly for NixOS system installation.

The (paths to these) scripts are meant to me passed in the scripts argument to mkSystemsFlake (see flake.nix for an example), which makes their functions available in the per-host devShells/apps. Host-specific nix variables are available to the bash functions as @{...} through substituteImplicit with the respective host as root context. Any script passed later in scripts can overwrite the functions of these (earlier) default scripts.

With the functions from here, a simple four-liner is enough to do a completely automated NixOS installation:

function install-system {( set -eu # 1: diskPaths
    prepare-installer "$@"
    do-disk-setup "${argv[0]}"
    init-or-restore-system
    install-system-to $mnt
)}

install-system Documentation

The above function performs the mostly automated installation of any $HOST from ../../hosts/ to the local disk(s) (or image file(s)) $DISK. On a NixOS host, this script can be run by root as: # ( cd /etc/nixos/ && nix run .#"$HOST" -- install-system "$DISK" ).

Doing an installation on non-NixOS (but Linux), where nix isn't installed for root, is a bit of a hack, but works as well. In this case, all nix commands will be run as $SUDO_USER, but this script and some other user-owned (or user-generated) code will (need to) be run as root. If that is acceptable, run with sudo as first argument: $ ( cd /etc/nixos/ && nix run .#"$HOST" -- sudo install-system "$DISK" ) (And then maybe sudo bash -c 'chown $SUDO_USER: '"$DISK" afterwards.)

The nix run in the above commands substitutes a number of @{-prefixed variables based on the $HOST name and its configuration from ../hosts/, and then sources this script and calls the install-system function. If $DISK points to something in /dev/, then it is directly formatted and written to as block device, otherwise $DISK is (re-)created as raw image and then used as loop device. For hosts that install to multiple disks, pass a :-separated list of <disk-name>=<path> pairs (the name may be omitted only for the default disk).

Once done, the disk can be transferred -- or the image be copied -- to the final system, and should boot there. If the host's hardware target allows, a resulting image can also be passed to register-vbox to create a bootable VirtualBox instance for the current user. The "Installation" section of each host's documentation should contain host specific details, if any.