What is Supervisor?

Using Supervisor is convenient when working with continuously running processes on a VPS or a dedicated server. It helps automate the startup and control of services, ensuring stable project operation.

Supervisor is a process manager that simplifies the management of long-running applications and provides an easy-to-use interface. It consists of a server component called supervisord, which creates and manages processes, and an interface called supervisorctl (command-line or web), used to control and monitor supervisord.

Installation

On Debian/Ubuntu, Supervisor can be installed from the repository:

apt-get install supervisor

After installation, Supervisor needs to be configured, and the programs or processes it will manage must be added. The configuration file is located at /etc/supervisor/supervisord.conf (for Ubuntu and Debian) or /etc/supervisord.conf on other systems.

To add a new process (worker), include the following section in the configuration file:

[program:worker]
command=/usr/bin/php /var/www/worker.php
stdout_logfile=/var/log/worker.log
autostart=true
autorestart=true
user=www-data
stopsignal=KILL
numprocs=1

Parameters:

• [program:worker] — the name of the process to which all following parameters apply;
• command=/usr/bin/php /var/www/worker.php — path to the executable file;
• stdout_logfile=/var/log/worker.log — log file for console output;
• autostart=true — automatically start the process when Supervisor starts;
• autorestart=true — automatically restart the process if it crashes;
• user=www-data — the user under which the process runs;
• stopsignal=KILL — the signal used to stop the process;
• numprocs=1 — the number of process instances to run.

After adding new processes, Supervisor must be restarted:

/etc/init.d/supervisor restart

Supervisor also provides a web interface through supervisorctl, which can be enabled in the configuration file. To do this, modify the [inet_http_server] section and specify the correct username and password:

[inet_http_server]
port=127.0.0.1:9001
;username=some_user_name
;password=some_password

Additional features

Supervisor includes a built-in event monitoring system that can send notifications about errors:

[eventlistener:memmon]
command=memmon -a 200MB -m error@site.com
events=TICK_60