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

<code>pip install supervisor</code>

Note: Supervisor does not support Windows.

Configuration

Generate a base configuration file:

<code>echo_supervisord_conf > /etc/supervisord.conf</code>

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:

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

Example program configuration for a Python script test.py :

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

Link the program file into the include directory:

<code>ln ./supervisor-test.ini /etc/supervisord.d/supervisor-test.ini</code>

Running Supervisor

Start the daemon:

<code>supervisord</code>

Control processes with supervisorctl (e.g., status , start , stop , restart , signal ).

Advanced Features

Process groups allow batch operations:

<code>[group:test]
programs=test-task_service, test-collector
</code>

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.