In Linux, Supervisor offers an efficient way to manage processes on UNIX systems, automating the restart of crashed processes and providing precise up/down status information.

In this tutorial, we will learn how to install Supervisor and configure it to manage the Nginx process on Ubuntu. This procedure is compatible with Ubuntu 20.04 and Ubuntu 22.04.

In This Article

Step 1 – Install Supervisor

By default, the Supervisor package is available in the Ubuntu default repository. You can install it with the following commands:

apt-get update -y
apt-get install supervisor -y

After installing Supervisor, you can verify the installed version of the Supervisor with the following command:

supervisord -v

You should get the following output:

4.2.1

Next, verify the status of the Supervisor service with the following command:

systemctl status supervisor

You should get the following output:

● supervisor.service – Supervisor process control system for UNIX

Loaded: loaded (/lib/systemd/system/supervisor.service; enabled; vendor preset: enabled)
Active: active (running) since Sun 2023-10-01 06:58:31 BST; 23s ago
Docs: http://supervisord.org
Main PID: 1074537 (supervisord)
Tasks: 1 (limit: 37964)
Memory: 17.2M
CPU: 144ms
CGroup: /system.slice/supervisor.service
└─1074537 /usr/bin/python3 /usr/bin/supervisord -n -c /etc/supervisor/supervisord.conf

Step 2 – Enable Supervisor Web Interface

Supervisor provides a web-based interface to manage all processes, but it is disabled by default. You can enable it by editing the file /etc/supervisor/supervisord.conf.

nano /etc/supervisor/supervisord.conf

Add the following lines:

[inet_http_server]
port=*:9001
username=admin
password=admin

Save and close the file, then restart the Supervisor service to apply the changes:

systemctl restart supervisor

Step 3 – Manage the Nginx Process with Supervisor

In this section, we will learn how to control the Nginx process with Supervisor.

First, install the Nginx server with the following command:

apt-get install nginx -y

After installing Nginx, you will need to stop and disable the Nginx service as we will use Supervisor to manage the Nginx process.

You can stop and disable the Nginx service with the following command:

systemctl stop nginx
systemctl disable nginx

Next, you will need to create a standalone configuration file for each service that you want to manage. You can create an Nginx configuration file with the following command:

nano /etc/supervisor/conf.d/nginx.conf

Add the following lines:

[program:nginx]
command=/usr/sbin/nginx -g "daemon off;"
autostart=true
autorestart=true
startretries=5
numprocs=1
startsecs=0
process_name=%(program_name)s_%(process_num)02d
stderr_logfile=/var/log/supervisor/%(program_name)s_stderr.log
stderr_logfile_maxbytes=10MB
stdout_logfile=/var/log/supervisor/%(program_name)s_stdout.log
stdout_logfile_maxbytes=10MB

Save and close the file when you are finished. Next, tell the Supervisor to know about the new config:

supervisorctl reread

You should get the following output:

nginx: available

Next, tell Supervisor to start the Nginx service:

supervisorctl update

You should get the following output:

nginx: added process group

Next, verify whether Supervisor started the Nginx service with the following command:

supervisorctl

You should get the following output:

nginx:nginx_00                   RUNNING   pid 15717, uptime 0:00:13

If you want to stop the Nginx service, run the following command:

stop nginx:nginx_00

Output:

nginx:nginx_00: stopped

To start the Nginx service again, run the following command:

start nginx:nginx_00

Output:

nginx:nginx_00: started

Now, exit from the Supervisor shell with the following command:

exit

You can also verify the Nginx process with the following command:

ps aux | grep nginx

You should get the following output:

root       15721  0.0  0.4  57176 10064 ?        S    14:14   0:00 nginx: master process /usr/sbin/nginx -
g daemon off;
www-data   15722  0.0  0.2  57828  5340 ?        S    14:14   0:00 nginx: worker process
www-data   15723  0.0  0.2  57828  5340 ?        S    14:14   0:00 nginx: worker process

Step 4 – Access Supervisor Web Interface

You can now access the Supervisor web interface using the URL http://your-server-ip:9001. You will be asked to provide a username and password as shown below:

Provide your admin username and password that you have defined in the configuration file, then click on the Sign-in button. You should see the Supervisor web interface in the following page:

Conclusion

In this guide, you learned how to install Supervisor and enable the web interface on Ubuntu. You also learned how to control the Nginx process with Supervisor. Try controlling processes on your Linux VPS hosting account with Atlantic.Net!