jupyterlab_ynh/scripts/experimental_helper.sh

#!/bin/bash

# Start (or other actions) a service,  print a log in case of failure and optionnaly wait until the service is completely started
#
# usage: ynh_systemd_action [-n service_name] [-a action] [ [-l "line to match"] [-p log_path] [-t timeout] [-e length] ]
# | arg: -n, --service_name= - Name of the service to reload. Default : $app
# | arg: -a, --action=       - Action to perform with systemctl. Default: start
# | arg: -l, --line_match=   - Line to match - The line to find in the log to attest the service have finished to boot.
#                              If not defined it don't wait until the service is completely started.
# | arg: -p, --log_path=     - Log file - Path to the log file. Default : /var/log/$app/$app.log
# | arg: -t, --timeout=      - Timeout - The maximum time to wait before ending the watching. Default : 300 seconds.
# | arg: -e, --length=       - Length of the error log : Default : 20
ynh_systemd_action() {

	# Declare an array to define the options of this helper.
	declare -Ar args_array=([n]=service_name= [a]=action= [l]=line_match= [p]=log_path= [t]=timeout= [e]=length=)
	local service_name
	local action
	local line_match
	local length
	local log_path
	local timeout

	# Manage arguments with getopts
	ynh_handle_getopts_args "$@"

	local service_name="${service_name:-$app}"
	local action=${action:-start}
	local log_path="${log_path:-/var/log/$service_name/$service_name.log}"
	local length=${length:-20}
	local timeout=${timeout:-300}

	ynh_print_info "Waiting for a response from $service_name..."

	# Start to read the log
	if [[ -n "${line_match:-}" ]]; then
		local templog="$(mktemp)"
		# Following the starting of the app in its log
		if [ "$log_path" == "systemd" ]; then
			# Read the systemd journal
			journalctl -u $service_name -f -n0 >"$templog" &
		else
			# Read the specified log file
			tail -F -n0 "$log_path" >"$templog" &
		fi
		# Get the PID of the tail command
		local pid_tail=$!
	fi

	echo "${action^} the service $service_name" >&2
	systemctl $action $service_name ||
		(
			journalctl --lines=$length -u $service_name >&2 \
				;
			test -n "$log_path" && echo "--" && tail --lines=$length "$log_path" >&2 \
				;
			false
		)

	# Start the timeout and try to find line_match
	if [[ -n "${line_match:-}" ]]; then
		local i=0
		for i in $(seq 1 $timeout); do
			# Read the log until the sentence is found, that means the app finished to start. Or run until the timeout
			if grep --quiet "$line_match" "$templog"; then
				echo "The service $service_name has correctly started." >&2
				break
			fi
			echo -n "." >&2
			sleep 1
		done
		if [ $i -eq $timeout ]; then
			echo "The service $service_name didn't fully started before the timeout." >&2
			journalctl --lines=$length -u $service_name >&2
			test -n "$log_path" && echo "--" && tail --lines=$length "$log_path" >&2
		fi

		echo ""
		ynh_clean_check_starting
	fi
}

# Clean temporary process and file used by ynh_check_starting
# (usually used in ynh_clean_setup scripts)
#
# usage: ynh_clean_check_starting
ynh_clean_check_starting() {
	# Stop the execution of tail.
	kill -s 15 $pid_tail 2>&1
	ynh_secure_remove "$templog" 2>&1
}