POTD wallpaper - flow/process and interaction with providers

The previous discussion I started here did not address my questions so I am starting another thread with the hope of getting more information on the POTD wallpaper (specifically APOD from NASA) code/flow/process.

The outage I spoke of in the first thread was only an issue with the Plasma DE. It wasn’t apparent on a KDE4 DE that is resident on the same home network and during the same time frame that the outage occurred.

  1. Can the code be easily modified to provide log files for when the image is not successfully applied to the desktop wallpaper?
  2. Is there an intermediate fetching point to download the image (e.g. plasmapotd.freedesktop.org) -or- does it get downloaded directly on the host file system - e.g. /tmp/potd_image.jpg?
  3. Is the same executable “plasma-apply-wallpaperimage <image_file>” used to apply the wallpaper?
  4. I was unsuccessful in creating a script using the above executable to be run from cron because I couldn’t get the needed processes running inside the script - i.e. kactivitymanager daemon and plasmashell service.

It would be really helpful to understand the process that POTD wallpaper does so I can debug this going forward.

Thank you KDevelopers for your reply to this!

If KDE4’s APOD and other providers in Plasma 5 work, APOD in Plasma 5 should also work because the link is still the same. Perhaps your network is somewhat broken so I have submitted a change to let APOD always use https when fetching images.

Regarding other questions:

  1. Yes, and there should be some debug messages already if you enable the debug flag using QT_LOGGING_RULES="kde.wallpapers.potd.debug=true"

  2. It saves images to ~/.cache/plasma_engine_potd

  3. No, the process is handled internally.

  4. I think you may need to use su -l -c "yourcommand" to to provide a full login session for the custom script.

Thank you very much for your reply fusionfuture. This is very helpful!