How to launch a process in background & autorestart?

In this guide on VPS administration, we will explain how to let a background application such as a discord bot, a nodejs application or a game server (minecraft, gmod, fivem, etc) run on supervisor on a Linux VPS under Debian , Ubuntu or CentOS.

This method allows you to keep an application running even if you disconnect from your VPS. Moreover, Supervisor offers additional features, to facilitate the management of processes, debugging with logs, and permit an automatic restart in case of crash.

Install Supervisor

Supervisor is an application for linux systems allowing to control a process. You must have administrator rights to enter the following commands.

To install it, we will use the package manager.

Installation of Supervisor on Debian

To install Supervisor on Debian :

apt update && apt install -y supervisor

Installation of Supervisor on Ubuntu

To install Supervisor on Ubuntu :

sudo apt update && sudo apt install -y supervisor

Installation of Supervisor on CentOS

To install Supervisor on CentOS :

yum install supervisor

Configuration of supervisord

Supervisord is the responsible part for starting and monitoring the configured applications. It will also restart these processes in case of a crash, if specified in the configuration. The general configuration is done in the file /etc/supervisor/supervisord.conf.

Below you will find several configuration examples, for bot discord or game server.

To take into account any new configuration:

/etc/init.d/supervisor restart

Automatic reboot for a Discord Bot

To manage the automatic launch and restart of a discord bot, create a new file /etc/supervisor/conf.d/bot-discord.conf with a configuration like this:

[program:discord_bot]
directory=/var/www/discord/
command=node index.js
autorestart=true
user=www-data
redirect_stderr=true
stdout_logfile=/var/www/discord/bot.log
stdout_logfile_maxbytes=50MB
startretries=3
startsecs=0
  • directory contains the directory where your bot discord is.
  • command contains the command to launch the discord bot.
  • autorestartà true for an automatic restart in case of a crash discord.
  • user contains the name of the system user who will start the process.
  • redirect_stderr on true to get the bots errors in the log file.
  • stdout_logfile contains the path to the bot's log file, it will contain the feedback displayed by the bot.
  • stdout_logfile_maxbytes is the maximum size of the log file.
  • startretries indicates the number of error starts before the autorestart is disabled. Prevents a looping restart in case of an error.

Automatic game server restart

To manage the automatic start and restart of a game server, create a new file /etc/supervisor/conf.d/gameserver.conf with a configuration like:

[program:gameserver]
directory=/home/minecraft/server/
command=java -jar minecraft_server.js
autorestart=true
user=minecraft
redirect_stderr=true
stdout_logfile=/home/minecraft/server/gameserver.log
stdout_logfile_maxbytes=100MB
startretries=3
startsecs=0
  • directory contains the directory where your bot discord is.
  • command contains the command to launch the discord bot.
  • autorestartà true for an automatic restart in case of a crash discord.
  • user contains the name of the system user who will start the process.
  • redirect_stderr on true to get the bots errors in the log file.
  • stdout_logfile contains the path to the bot's log file, it will contain the feedback displayed by the bot.
  • stdout_logfile_maxbytes is the maximum size of the log file.
  • startretries indicates the number of error starts before the autorestart is disabled. Prevents a looping restart in case of an error.

Supervisord commands

A multitude of commands are available, to see the complete list, type man supervisorctl.

Start supervisord

/etc/init.d/supervisor start

Stop supervisord

/etc/init.d/supervisor stop

Restart supervisord

/etc/init.d/supervisor restart

Process status

To display the list of processes configured in supervisord and their status (started, stopped, crashed, etc):

supervisorctl status

Will return by example:

discord_bot                      RUNNING   pid 6183, uptime 17:08:51

Start a process

supervisorctl start PROCESSNAME

Stop a process

supervisorctl stop PROCESSNAME

Restart a process

supervisorctl restart PROCESSNAME