Using Supervisor for Process Monitoring and Management on Unix-like Systems

Supervisor is a client/server process monitoring and management tool for Unix-like operating systems, designed to improve the stability of long‑running background services such as API servers or consumer processes.

Problem scenario : Deploying persistent processes with nohup cmd & can lead to unexpected termination, causing service interruptions.

Supervisor addresses this by automatically restarting failed processes and supporting grouped management.

Installation

pip install supervisor

Note: Supervisor does not support Windows.

Configuration

Generate a base configuration file: echo_supervisord_conf > /etc/supervisord.conf Key sections include [unix_http_server], [supervisord], [supervisorctl], and optional [include] to load additional program files.

Create a directory for individual program configs and enable inclusion:

mkdir /etc/supervisord.d
[include]
files = /etc/supervisord.d/*.ini

Example program configuration for a Python script test.py:

[program:test]
command=python -u ./test.py
directory=/root/test/
redirect_stderr=true
stdout_logfile=/root/test/test.log

Link the program file into the include directory:

ln ./supervisor-test.ini /etc/supervisord.d/supervisor-test.ini

Running Supervisor

Start the daemon: supervisord Control processes with supervisorctl (e.g., status, start, stop, restart, signal).

Advanced Features

Process groups allow batch operations:

[group:test]
programs=test-task_service, test-collector

Use commands like stop test: to affect all members of the group.

Program options such as command, directory, numprocs, autostart, stdout_logfile, and redirect_stderr provide fine‑grained control.

Auto‑restart policy is governed by autorestart (values: true, false, unexpected) and exitcodes. Experiments show that processes exiting with unexpected codes or being killed are automatically restarted, while normal exits are not.

Start‑up verification uses startsecs to determine if a process has started successfully; failures within this window trigger back‑off and eventual FATAL status.

Web interface can be enabled via [inet_http_server] for visual management, but should be secured.

Conclusion

Supervisor offers a robust solution for managing persistent services, supporting configuration inheritance, process grouping, signal handling, and customizable restart behavior, making it a valuable tool for system administrators and DevOps engineers.