#!/bin/sh
set -eu

textfile_directory=/run/prom

s6rc_service_is_up() {
	if s6-rc -a list | grep -q "${1:?}"; then printf '1'; else printf '0'; fi
}

printmetric() {
	local name=${1:?}
	local labels=${2:?}
	local value=${3:?}
	printf '%s{%s} %s\n' "$name" "$labels" "$value"
}

services_count() {
	printf '# HELP s6_rc_services_count number of services\n'
	printf '# TYPE s6_rc_services_count gauge\n'
	for bundle in $(s6-rc-db list bundles); do
		printmetric 's6_rc_services_count' \
			$(printf 'bundle="%s"' $bundle) \
			$(s6-rc list $bundle | wc -l)
	done
}

services_up() {
	printf '# HELP s6_rc_service_up if a service is running\n'
	#printf '# TYPE s6_rc_service_up stateset\n'
	for bundle in $(s6-rc-db list bundles)
	do
		for service in $(s6-rc-db contents "$bundle")
		do
			printmetric 's6_rc_service_up' \
				$(printf 'bundle="%s",service="%s"' $bundle $service) \
				$(s6rc_service_is_up $service)
		done
	done
}

write_textfile() {
	mkdir -p "$textfile_directory" || exit 1

	tmp=$(mktemp --tmpdir metrics_s6_rc.XXXXX)

	(
		services_count
		services_up
	) | tee "$tmp"

	mv -v "$tmp" "$textfile_directory"/s6_rc.prom || exit 1

	chmod +r "$textfile_directory"/s6_rc.prom
	chown nobody:nobody "$textfile_directory"/s6_rc.prom
}

main() {
	write_textfile
}

main >/dev/null 2>&1