Python script not writing to config when run as a systemctl service

Question

I'm running a python 3 program on raspbian that must write a string value to a config file. I manage to write to config within the main script, but not within the "secondary" one.

-> When debugging in VS code (remote debugger), the secondary script correctly writes to config.txt.

-> When running as a service with sudo systemctl start myservice or su -c 'systemctl start myservice', the secondary script doesn't write to config.txt.

In both cases, the program runs to the end with no exception.

/home/pi/project/my-script.py

# This is the main script. 
# If I move the configWrite method in this one, it writes correctly to config.

from lib import *

def main():
    secondary.authenticate()

if __name__ == '__main__':
    main()

/home/pi/project/lib/secondary.py

# This is the script which can't write to config.

import configparser
import logging
import requests

config = configparser.ConfigParser()   
configFilePath = r'/home/pi/project/config.txt'
config.read(configFilePath)
cfg = config['main']
sid = cfg['sid']

def configWrite(field, value):
    config.set('secondary', field, value)
    with open(configFilePath, 'w') as configfile:
        config.write(configfile)

def authenticate():
    authenticate_url = '...'
    headers = { ... }
    try:
        response = requests.post(authenticate_url, headers=headers, timeout=(30, 10))
        response.raise_for_status()
    except Exception as err:
        logging.warning('Error occurred: {}'.format(err))
        return False
    else:
        global sid
        sid = response.json()['sid']
        configWrite('sid', str(sid))
        return True

/home/pi/project/config.txt (chmodded to 666)

[main]
someitem = foo

[secondary]
sid = bar

/etc/systemd/system/myservice.service

[Unit]
Description=My service description
After=network.target

[Service]
ExecStart=/usr/bin/python3 -u my-script.py
WorkingDirectory=/home/pi/project
StandardOutput=Inherit
StandardError=Inherit
Restart=always
User=pi

[Install]
WantedBy=multi-user.target

Similar question here but with no valid answer : running python script as a systemd service
I can see that the service runs properly to the end of the script by checking the logs (logging works just fine either way)
No error in journalctl
I rebooted the raspberry pi already
Python version 3.5.3

Jojo · Accepted Answer · 2019-12-17 12:56:17Z

0

I'm not sure, but it looks like you never set the config['main'] to your new value. Try in configWrite(field, value): config['main'] = {field: value} and then write it to your config.txt like bevor.

answered Dec 17, 2019 at 12:56

Jojo

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5 Comments

Vinzz Over a year ago

That line was lost when paste-editing code for stackoverflow. I edited the question. Sorry for that

Jojo Over a year ago

Then I would try to add the absolut path for the scipt at ExecStart. That solved the problem for me. Like ExecStart=/usr/bin/python3 -u /home/pi/project/my-script.py

Vinzz Over a year ago

Nope, the script is still not writing to config

Jojo Over a year ago

I guess the requests import was also lost while copying? Have you tried to run the service as root?

Vinzz Over a year ago

I edited the question to restore the requests import. I also tried the su command (which unfortunately produces the same result as the sudo command)

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