Unable to import pandas on a linux service

I'm trying to create a simple service using Python and the service needs to import pandas for manipulating dataframes. I noticed that when I use "import pandas as pd", the service failed. I created a example to show the behavior.

Script main2.py (location: /home/silas/Desktop):

import pandas as pd
import logging
import time

while True:
    print('hello world')

    time.sleep(10)

my_service.service (location: /etc/systemd/system):

[Unit]
Description=Example
After=network.target

[Service]
ExecStart=/usr/bin/python3 /home/silas/Desktop/main2.py
Restart=always

[Install]
WantedBy=default.target

I opened the prompt and executed the commands:

systemctl start my_service.service
systemctl enable my_service.service
systemctl status my_service.service

I got the response telling me that my service is not running and failed:

 my_service.service - Example
      Loaded: loaded (/etc/systemd/system/my_service.service; enabled; vendor pr>
      Active: failed (Result: exit-code) since Tue 2023-08-08 19:49:53 -03; 1min>
 Main PID: 8776 (code=exited, status=1/FAILURE)
    CPU: 63ms

If I change the script to:

 import logging
 import time


 while True:

     print('hello world')

     time.sleep(10)

And execute the commands:

systemctl stop my_service.service
systemctl disable my_service.service
systemctl start my_service.service
systemctl enable my_service.service
systemctl status my_service.service

I got the response telling me that the service is running:

y_service.service - Example
     Loaded: loaded (/etc/systemd/system/my_service.service; enabled; vendor pr>
     Active: active (running) since Tue 2023-08-08 19:54:31 -03; 10s ago
   Main PID: 8952 (python3)
      Tasks: 1 (limit: 8994)
     Memory: 4.2M
        CPU: 26ms
     CGroup: /system.slice/my_service.service
             └─8952 /usr/bin/python3 /home/silas/Desktop/main2.py

Is possible to use pandas in this way? If so, what I'm doing wrong? If is not possible, how can I create a service using pandas?

Obs1: Pandas is installed in my machine, I'm not using virtual environment.

Obs2: If I execute the script with python3 main2.py, works normally with pandas.

Obs3: If I type which python3 in my prompt, shows the path configured in my_service.service.

I discovered that I can set the user in my .service file. I set my user in this format:

my_service.service:

[Unit]
Description=Example
After=network.target

[Service]
User=your_current_user
ExecStart=/usr/bin/python3 /home/silas/Desktop/main2.py

[Install]
WantedBy=default.target

Then I used the command:

sudo systemctl restart my_service.service

The service worked with pandas.

You can also run a systemd service on the user level by putting it in $XDG_CONFIG_HOME/systemd/user and start the service with the --user flag. ($XDG_CONFIG_HOME for me is ~/.config)

systemctl enable --now --user my_service.service

You would have to use the --user flag on anything for it from there, like checking the status or disable or stop, etc

In addition to the answer (just a side note).

We can check the list of paths, where python is searching for modules:

import logging

logging.basicConfig(
	filename='/path/to/my_service.log',
	level=logging.DEBUG,
	filemode='a')
logging.debug('Importing pandas')
try:
	import pandas
except Exception as e:
	logging.error('Failed to import pandas', exc_info=True)
	logging.debug('sys.path=[\n'+"\n".join(sys.path)+'\n]')
else:
	logging.debug('Succesfully imported pandas')

I guess that Pandas was installed like pip install --user pandas in a user folder. To check this we can run in REPL:

import pandas; print(pandas.__file__)   # maybe somewhere in /home/silas/.local/lib/python3/site-packages/pandas in this case

When running a service, python will be started by a root user. So sys.path will be configured ignoring your local site-packeges. It's possible to add the path manually like sys.path.append(your_pandas_path) but hardly it's a good decision. User=your_current_user in a service is the right choice.