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.