1 files changed, 157 insertions, 0 deletions
diff --git a/common.sh b/common.sh
new file mode 100644
index 0000000..995a57e
--- /dev/null
+++ b/common.sh
@@ -0,0 +1,157 @@
+# Common Bash functions for helper scripts in this repository
+set -eu
+
+## Logging #####################################################################
+_print() {
+	local color="\e[$1m"
+	local clrcolor="\e[0m"
+	shift
+	if [ ! -t 1 ]; then
+		color=""
+		clrcolor=""
+	fi
+	printf "${color}%s${clrcolor}\n" "$*" >&2
+}
+
+stage() {
+	_print '1;32' "$@"
+}
+
+info() {
+	_print '1;35' "$@"
+}
+
+error() {
+	_print '1;31' "$@"
+}
+warning() {
+	_print '1;33' "$@"
+}
+
+## SSH access helper ###########################################################
+
+# Convert hostname to the SSH destination
+sshdest() {
+	awk -F- 'NF > 1 { print $2"."$1; exit } { print $1 }' <<<"$1"
+}
+
+_ssh() {
+	local device="$1"
+	shift
+	if [ "$device" != "$(hostname)" ]; then
+		local -a args
+		[ "$1" = "sudo" ] && \
+			args+=('-t') # Crude detection for terminal need
+		ssh "${args[@]}" "$(sshdest "$device")" -- "$@"
+	else
+		"$@"
+	fi
+}
+
+## Evalutions and queries ######################################################
+
+# The path where build result is linked to
+result() {
+	echo ".result-$1"
+}
+
+# Get system of the device
+device_system() {
+	nix eval --raw ".#nixosConfigurations.$1.config.nixpkgs.system"
+}
+
+# Validates if link is valid.
+build_validate() {
+	local device="$1"
+	[ -L "$(result "$device")" ] && [ -e "$(result "$device")" ]
+}
+
+## Build NixOS system ##########################################################
+# $1: device name
+# All other arguments are passed to the nix build command
+build() {
+	local device="$1"
+	shift
+
+	local toplevel=".config.system.build.toplevel"
+	if [ "$(device_system "$device")" = "armv7l-linux" ]; then
+		toplevel=".config.system.build.cross.x86_64-linux${toplevel}"
+	fi
+
+	stage "Building system for device: $device"
+	nix build \
+		-o "$(result "${device}")" \
+		--keep-going \
+		"$@" \
+		"${0%/*}#nixosConfigurations.${device}${toplevel}"
+}
+
+## Copy NixOS system ###########################################################
+# $1: device name
+copy() {
+	local device="$1"
+	if ! build_validate "$device"; then
+		warning "System for device '$device' seems to be not build." >&2
+		return 1
+	fi
+	local store
+	store="$(readlink -f "$(result "$device")")"
+
+	local freespace required;
+	freespace="$(_ssh "$device" df -B 1 /nix | awk 'NR == 2 { print $4 }')"
+	required="$(nix path-info -S "$store" | awk '{ print $2 }')"
+	info "Free space on device: $(numfmt --to=iec "$freespace")"
+	info "Required space: $(numfmt --to=iec "$required")"
+	if [ "$required" -ge "$freespace" ]; then
+		error "There is not enough space to copy clousure to: $device" >&2
+		return 1
+	fi
+
+	stage "Copy closure to: $device"
+	nix copy -s --to "ssh://$(sshdest "$device")" "$store"
+}
+
+## Switch Nix encironment ######################################################
+# $1: switch operation to be performed
+# $2: device name
+# TODO possibly really query if switch is or is not required
+setenv() {
+	local switchop="$1"
+	local device="$2"
+	if ! build_validate "$device"; then
+		warning "System '$device' seems to be not build." >&2
+		return 1
+	fi
+	local store
+	store="$(readlink -f "$(result "$device")")"
+
+	stage "${switchop^} system: $device"
+	local cursystem
+	cursystem="$(_ssh "$device" readlink -f /nix/var/nix/profiles/system)"
+	if [ "$cursystem" != "$store" ]; then
+		info "-----------------------------------------------------------------"
+		_ssh "$device" \
+			nix store diff-closures "$cursystem" "$store"
+		info "-----------------------------------------------------------------"
+		# TODO we should call here switch-to-configuration as well to use single
+		# sudo session and remove one prompt.
+		_ssh "$device" \
+			sudo sh -c \
+				'nix-env --profile /nix/var/nix/profiles/system --set "$store" && /nix/var/nix/profiles/system/bin/switch-to-configuration "$1"' \
+					"$switchop"
+	else
+		warning "The latest system might have been already set."
+	fi
+}
+
+boot() {
+	setenv boot "$1"
+}
+
+switch() {
+	setenv switch "$1"
+}
+
+switch_test() {
+	setenv test "$1"
+}