From 9996cca17aeb63ed0d51d59d4572dced0b050aee Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Karel=20Ko=C4=8D=C3=AD?= <cynerd@email.cz>
Date: Sun, 4 Dec 2022 21:39:25 +0100
Subject: install.sh: add ability to install non-native architecture

The result is that it now requires to be run only on NixOS but that
should be fine.
---
 install.sh | 79 +++++++++++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 55 insertions(+), 24 deletions(-)

(limited to 'install.sh')

diff --git a/install.sh b/install.sh
index a0ec3b7..823a9f5 100755
--- a/install.sh
+++ b/install.sh
@@ -1,37 +1,68 @@
 #!/bin/sh
 set -eu
-hostname="${1:-$(hostname)}"
-root="${2:-}"
-
-_sudo() {
-	if [ "$(id -u)" -ne 0 ]; then
-		"$@"
-	else
-		sudo -p 'Sudo password: ' -- "$@"
-	fi
-}
-
-if [ "$hostname" = "nixos" ]; then
-	echo "The hostname is the default one, that is not right for sure." >&2
-	echo "Please specify the correct hostname as the first argument!" >&2
+hostname="$1"
+root="${2:-$(pwd)}"
+src="$(readlink -f "${0%/*}")"
+
+if [ "$(id -u)" -ne 0 ]; then
+	echo "Run this as root!" >&2
 	exit 1
 fi
 
+if ! command -v git >/dev/null; then
+	exec nix shell 'nixpkgs#git' -c "$0" "$@"
+fi
+
 if [ ! -s "$root/.personal-secrets.key" ]; then
 	echo "Please paste the personal secret key (terminate using ^D)" >&2
 	sudo tee "$root/.personal-secrets.key" >/dev/null
 fi
 
-eval "$(ssh-agent)"
-echo "Please paste the SSH access key now (terminate using ^D):" >&2
-ssh-add -
-trap 'kill "$SSH_AGENT_PID"' EXIT
+if [ -f "$src/flake.nix" ]; then
+	flake="$src"
+else
+	flake="git+https://git.cynerd.cz/nixos-personal"
+	eval "$(ssh-agent)"
+	echo "Please paste the SSH access key now (terminate using ^D):" >&2
+	ssh-add -
+	trap 'kill "$SSH_AGENT_PID"' EXIT
+fi
+
+buildSystem="$(nix eval --raw --impure --expr 'builtins.currentSystem')"
+targetSystem="$(nix eval --raw "$flake#nixosConfigurations.$hostname.pkgs.system")"
 
-flake="git+https://git.cynerd.cz/nixos-personal#$hostname"
-if [ -z "$root" ]; then
-	nix shell nixpkgs\#git --command \
-		"_sudo \"\$(command -v nixos-rebuild)\" switch --flake '$flake' --fast"
+toplevel="config.system.build.toplevel"
+if [ "$buildSystem" != "$targetSystem" ]; then
+	toplevel="config.system.build.cross.$buildSystem.$toplevel"
+fi
+
+if [ -f "$src/flake.nix" ]; then
+	# Build in system when running from sources
+	result="$(nix build --no-link --print-out-paths \
+		"$flake#nixosConfigurations.$hostname.$toplevel")"
+	nix copy --to "$root" "$result" 
 else
-	nix shell nixpkgs\#git nixpkgs\#nixos-install-tools --command \
-		"_sudo \"\$(command -v nixos-install)\" --flake '$flake' --root '$root'"
+	result="$(nix build --no-link --print-out-paths \
+		"$flake#nixosConfigurations.$hostname.$toplevel" \
+		--store "$root" --extra-substituters 'auto?trusted=1')"
+fi
+
+nix-env --store "$root" --extra-substituters 'auto?trusted=1' \
+	-p "$root/nix/var/nix/profiles/system" --set "$result"
+
+# Mark the target as a NixOS installation, otherwise switch-to-configuration will chicken out.
+mkdir -m 0755 -p "$root/etc"
+touch "$root/etc/NIXOS"
+
+# Copy over binfmt runners if required
+if [ "$buildSystem" != "$targetSystem" ]; then
+	mkdir -p "$root/run/binfmt"
+	for binfmt in /run/binfmt/*; do
+		nix copy --to "$root" "$(readlink -f "$binfmt")" 
+		ln -sf "$(readlink -f "$binfmt")" "$root/$binfmt"
+	done
 fi
+
+ln -sfn /proc/mounts "$root/etc/mtab" # Grub needs an mtab.
+NIXOS_INSTALL_BOOTLOADER=1 nixos-enter --root "$root" -- \
+	/nix/var/nix/profiles/system/bin/switch-to-configuration boot
-- 
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