It looks like the log file .config/joplin-desktop/log.txt never gets truncated/rotated by Joplin itself (this applies probably to the other log files as well).
Do I miss something or should/can I create a logrotate conf file snippet on my Linux system myself?
Nope, you’re not missing anything. There’s currently no rotation. But I like the idea.
As for the logrotate question, I’m not sure. I don’t know, if the logger process keeps the file pointer open, and what would happen, if one were to just remove the underlying file. Maybe @laurent can answer this.
I think the file doesn’t stay open between writes so it should be fine to rotate it. Eventually we should integrate this feature to the app too as it’s true the log keeps growing without limit at the moment.
This will rotate weekly (and compress) every log file found in /home/user/.config/joplin-desktop/ and keep 4 old files.
Hint: one does not need to restart any service after putting this file into place (/etc/logrotate.d) since logrotate is not a daemon but started via crontab/systemd timer.