remote access to logisim-evolution?

[rm144]

When I try to start logisim-evolution on a remote machine (Ubuntu, both on local and remote machine, remote login via ssh -X), I get the following error:

% logisim-evolution
Picked up _JAVA_OPTIONS: -Duser.home=/home/myname/snap/logisim-evolution/4
Exception in thread "main" java.awt.AWTError: Can't connect to X11 window server using 'localhost:10.0' as the value of the DISPLAY variable. 

whereas other programs with graphical interface running on the remote machine can display their windows on the local machine.

This seems to be a Java-related problem, and https://stackoverflow.com/a/11525353/3852630 suggests to pass the option
-Djava.awt.headless=true to Java. All the other X11-related solutions (setting DISPLAY, xhost + etc.) didn't work for me.

Does anyone know how I can start logisim-evolution on a remote Linux machine or how this Java option can be passed to logisim-evolution?

It would be nice if our students could work on the machines in our lab from remote.

Thanks for your help!

Ralf

[maehne]

You seem to be using Logisim-evolution packaged as a Snap. Could you please test using the native DEB package and JAR archive (version 3.8.0 and nightly build), whether they show also this behaviour?

[rm144]

So it could be a problem with the sandbox?

[maehne]

Yes.

[rm144]

Ah, I see, thanks a lot! I can report how to start it from remote when it is installed via flatpak: flatpak --share=network run com.github.reds.LogisimEvolution. Without the --share=network, I get the same error as described in my question. So I have to figure out how to do the same with snap.

[rm144]

I did not succeed for snap (none of the solutions from https://forum.snapcraft.io/t/x11-forwarding-using-ssh/2381 and https://stackoverflow.com/questions/61933724/snap-applications-through-a-remote-x11-session helped). So if anyone has an idea, I'd be grateful. But I can live with the flatpak solution for now and maybe abandon the snap solution on the laptop. Thanks a lot for your help!

[maehne]

So executing export XAUTHORITY=$HOME/.Xauthority on the remote host prior launching Logisim-evolution from the same shell did not help?

As it seems to be a Snap limitation rather a problem in our packaging, I won't create an issue for the moment. Nevertheless, it would be nice to post here if you should find any solution.

[rm144]

No, unfortunately setting XAUTHORITY didn't work for me, and also creating the symbolic link from the snap directory to $HOME/.Xauthority didn't help.

Do you happen to know how I could pass -Djava.awt.headless=true (maybe in addition) to logisim-evolution? But maybe that's difficult, because logisim-evolution is actually a link to /usr/bin/snap and not the binary of logisim-evolution, and then there's also Java involved at some point.

[maehne]

The option -Djava.awt.headless=true needs to be added to line 47 of snapcraft.yaml and then you need to build the Snap.

[rm144]

Thanks a lot! I'll need to find some quiet moment to test this.