Pygame.mixer does not play sound when started in cron

Question

I have written a small python script that plays a track after the press of a button (and ignores further button presses until the track has completed). The script works perfectly fine when started from terminal, but I simply cannot find a way to make it start on reboot with cron. Here is the script hoelderlinbutton.py:

import pygame
pygame.init()
pygame.mixer.init()
music = pygame.mixer.music.load("/home/pi/Hoelderlin.mp3")
from signal import pause
from gpiozero import Button
def on_press ():
   if pygame.mixer.music.get_busy() == False:
      pygame.mixer.music.play()
button = Button(2)
button.when_pressed = on_press
pause()

The relevant line in crontab -e is:

@reboot /usr/bin/python3 /home/pi/hoelderlinbutton.py

Upon reboot, nothing happens after pressing the button. I've activated cron logging (Where do Cron error message go?) but the log indicates that the script was executed. I tried to log for any errors from the script by changing the line in crontab to this:

@reboot /usr/bin/python3 /home/pi/hoelderlinbutton.py > /home/pi/logs/backup.log 2>&1

But the created log file is empty.

I then experimented, based on various hints and ideas from previous posts and answers by:

• using either sudo crontab -e or crontab -e;
• changing the working directory in crontab with @reboot cd /home/pi && /usr/bin/python3 /home/pi/hoelderlinbutton.py;
• Executing the script in the background by appending & at the end;
• SettingXDG_RUNTIME_DIR=/run/user/1000 earlier in crontab -e or sudo crontab -e (see: https://wiki.archlinux.org/title/PulseAudio#Play_sound_from_a_non-interactive_shell_.28systemd_service.2C_cron.29
• Executing the script for user pi in sudo crontab -e, i.e. @reboot sudo -u pi /usr/bin/python3 /home/pi/hoelderlinbutton.py (See No methods for running python script on startup are working)

But none of this got me anywhere. I'm a little out of my depth here, but I believe that some limitation in the crontab environment prevents the actual playing of the track (or perhaps causes an issue with the GPIO). Any ideas what else I can try?

Answer 1

Yes, Dougie's proposal works -- I wish I had asked earlier! I removed the crontab entries and instead edited the autostart configuration with

sudo nano /etc/xdg/lxsession/LXDE-pi/autostart

and then added

@/usr/bin/python /home/pi/hoelderlibutton.py

in the second-to-last line. And then all is working perfectly! In the longer term, I'd love to understand why it did not function in cron -- but for now I'm just happy to have this working. Thanks, Dougie!