Broken attempt at adding NixOS support to `brl fetch`

brl-fetch-nixos.sh

#!/bedrock/libexec/busybox sh
#
# NixOS bootstrap support
#
#      This program is free software; you can redistribute it and/or
#      modify it under the terms of the GNU General Public License
#      version 2 as published by the Free Software Foundation.
#
# Copyright (c) 2016-2018 Daniel Thau <danthau@bedrocklinux.org>
#

# errors trying to set up sandbox on nixos-install.  Could not find a way to disable it.

. /bedrock/share/common-code
trap 'fetch_abort "Unexpected error occurred."' EXIT

check_supported() {
	false
}

check_experimental() {
	false
}

distro_arch_name() {
	fetch_abort "brl-fetch does not support distro/architecture pair"
}

list_mirrors() {
	# Could not find a list of package mirrors.  This is the one found in-use by default on a fresh install.
	#
	echo "https://nixos.org/releases/"
}

speed_test_url() {
	echo "nix/latest/install"
}

list_releases() {
	echo "rolling"
}

default_release() {
	echo "rolling"
}

fetch() {
	step_init 99

	if [ -z "${target_dir:-}" ]; then
		fetch_abort "Essential variable not set"
	fi

	step "Determining name"
	name="${flag_name:-${distro}}"
	notice "Using ${color_strat}${name}${color_norm}"

	step "Determining CPU architecture"
	arch="$(distro_arch_name)"
	notice "Using ${color_file}${arch}${color_norm}"

	step "Determining release"
	release="${flag_release:-$(default_release)}"
	notice "Using ${color_file}${release}${color_norm}"

	step "Determining mirror"
	mirror="$(pick_mirror "$(speed_test_url)")"
	notice "Using ${color_link}${mirror}${color_norm}"

	step "Making directory structure"
	bootstrap_dir="${target_dir}/brl-bootstrap"
	mkdir -p "${target_dir}/etc/nix" "${bootstrap_dir}/target-root"

	step "Downloading bootstrap software"
	url="$(find_link "${mirror}/nix/latest/" "^nix-.*-${arch}-linux.tar.bz2")"
	wget -O "${bootstrap_dir}/nix.tar.bz2" "${url}"

	step "Extracting bootstrap software"
	tar xf "${bootstrap_dir}/nix.tar.bz2" -C "${bootstrap_dir}"

	step "Installing bootstrap software"
	for dir in bin sbin usr/bin usr/sbin etc dev nix root/.config/nix/ tmp proc etc/nix; do
		mkdir -p "${bootstrap_dir}/${dir}"
	done
	for file in etc/group etc/passwd; do
		touch "${bootstrap_dir}/${file}"
	done
	cp /bedrock/libexec/busybox "${bootstrap_dir}"
	chroot "${bootstrap_dir}" /busybox --install

	for cfg in "${target_dir}/etc/nix/nix.conf" "${bootstrap_dir}/etc/nix/nix.conf" "${bootstrap_dir}/root/.config/nix/nix.conf"; do
		(
			echo "build-users-group ="
			echo "sandbox = false"
			echo "build-use-sandbox = false"
			echo "trusted-users = root"
		)  > "${cfg}"
	done

	setup_chroot "${bootstrap_dir}"
	LC_ALL=C chroot "${bootstrap_dir}" /busybox addgroup nixbld
	LC_ALL=C chroot "${bootstrap_dir}" /busybox adduser -s /bin/sh -D -G nixbld -u 0 root
	LC_ALL=C chroot "${bootstrap_dir}" /bin/sh -c "/nix-*-${arch}-linux/install"
	LC_ALL=C chroot "${bootstrap_dir}" /bin/sh -c '. /root/.nix-profile/etc/profile.d/nix.sh ; nix-channel --add https://nixos.org/channels/nixos-19.03 nixpkgs' # TODO: look up proper channel
	LC_ALL=C chroot "${bootstrap_dir}" /bin/sh -c '. /root/.nix-profile/etc/profile.d/nix.sh ; nix-channel --update' # TODO: look up proper channel
	LC_ALL=C chroot "${bootstrap_dir}" /bin/sh -c '. /root/.nix-profile/etc/profile.d/nix.sh ; nix-env --option sandbox false -iE "_: with import <nixpkgs/nixos> { configuration = {}; }; with config.system.build; [ nixos-generate-config nixos-install ]"'
	LC_ALL=C chroot "${bootstrap_dir}" /bin/sh -c '. /root/.nix-profile/etc/profile.d/nix.sh ; nix-env --option sandbox false --install coreutils'

	step "Running bootstrap software"
	mount --bind "${target_dir}" "${bootstrap_dir}/target-root"
	LC_ALL=C chroot "${bootstrap_dir}" /bin/sh -c '. /root/.nix-profile/etc/profile.d/nix.sh ; nixos-generate-config --root /target-root'

	sed 's/boot.loader.grub.enable =.*/boot.loader.grub.enable = false;/g' "${target_dir}/etc/nixos/configuration.nix" > "${target_dir}/etc/nixos/configuration.nix-new"
	mv "${target_dir}/etc/nixos/configuration.nix-new" "${target_dir}/etc/nixos/configuration.nix"
	echo PAUSE; read PAUSE
	LC_ALL=C chroot "${bootstrap_dir}" /bin/sh -c '. /root/.nix-profile/etc/profile.d/nix.sh ; nixos-install --option sandbox false --root /target-root --no-root-passwd --no-bootloader'

	# . /root/.nix-profile/etc/profile.d/nix.sh
	# echo PAUSE; read PAUSE
	# chroot "${bootstrap_dir}" /bin/sh -c "/nix-*-${arch}-linux/install"
	# sudo PATH="$PATH" NIX_PATH="$NIX_PATH" "$(which nixos-install)" --root "/target-root"

	echo END-PAUSE; read PAUSE
}

:(

If it makes you feel any better, while I've had to switch focus elsewhere the effort to get this to work hasn't died. @unrooted is currently working on it.

Yes, that's right, I was trying my best and I still do from time to time. You, @xosefulk, or anyone reading this, can see the progress and what I've done in here. Sadly, I didn't have time to research this further, but feel free to comment there about your own effort if you try doing the same.