That is very interesting, and thanks for trying it out!
I think tho that it is working for you because the printer does ipp which you can see in lpinfo is supported. (tho it is showing up as a lpd device… maybe shared from another cups instance?)
The printer I am trying to use is only accessible via dnssd. It is an old laserjet with a usb dongle plugged into an Airport Express.
On the working systems it shows up with a dnssd uri like shown in the Device URIs section of https://www.cups.org/doc/admin.html
This works if I do something like:
DOCKER_API_VERSION=1.22 DOCKER_HOST=tcp://192.168.47.189:2375 docker-compose up --build
mounting dbus as a volume. But, does not work with any other deployment method. (and that is the only change needed)
I have this working in a dockerized version of our application. (Where I can modify the host as needed) But we are trying to move it over to Balena for easier deployment.
I noticed in the debug output for cups when clicking on the add printer button that it iterats over each connection method and shows this when trying to do dnssd:
[CGI] Unable to create Avahi client
I think this is related to why I can’t see this particular printer.
Thanks for you help.