Quickstart supervisor guide

supervisor is a UNIX utility to managing and respawning long running Python processes to ensure they are always running. Or according to its website:

Supervisor is a client/server system that allows its users to monitor and control a number of processes on UNIX-like operating systems.

Installation

supervisor can be installed with pip

$ pip install supervisor

Given a script test_proc.py, start the process under supervisor as

$ sudo supervisorctl start test_proc

Now it will run forever and you can see the process running with

$ sudo supervisorctl status
test_proc      RUNNING    pid 5586, uptime 0:00:11

You can stop the process with

$ sudo supervisorctl stop test_proc

Logs, by default, are written to /var/log/supervisor

The supervisor configuration can be found at /etc/supervisor/supervisor.conf

Configurations can be added to the supervisor.conf file for specific apps. Below we specify a configuration for the test_proc process, using a rotating file logger with two backups for both stdout amd stderr and a max file size of 100KBs.

[program:test_proc]
stdout_logfile=/var/log/supervisor/test_proc-stdout.log
stdout_logfile_maxbytes=100KB
stdout_logfile_backups=2
stderr_logfile=/var/log/supervisor/test_proc-stderr.log
stderr_logfile_maxbytes=100KB
stderr_logfile_backups=2

After the script runs for a while, the output logs will look something like this:

-rw-r--r-- 1 root root   101K Apr 14 18:50 test_proc-stdout.log.2
-rw-r--r-- 1 root root   101K Apr 14 19:09 test_proc-stdout.log.1
-rw-r--r-- 1 root root    32K Apr 14 19:15 test_proc-stdout.log

More configurations for supervisor can be found here.