This setup is entirely due to Niklas Hambüchen, sharing it here since it is tremendously useful.
Let’s say you have a server without a graphics card, and you want to use graphical programs directly on it. Here is a 3 step procedure to get a remote desktop supporting OpenGL applications:
Install turbovnc, for example by putting it into environment.systemPackages. TurboVNC supports software rendering through LLVMpipe, which is a software rasterizer for Mesa, which in turn is the most popular open-source implementation of OpenGL and in general the Linux graphics stack.
Set hardware.opengl.enable = true in /etc/nixos/configuration.nix. This will create /run/opengl-driver, containing the shared libraries that OpenGL applications will need to load.
Start the TurboVNC server with
server% Xvnc :30 -iglx -depth 24 -rfbwait 120000 -deferupdate 1 -localhost -verbose -securitytypes noneNote that the server will only listen to localhost, to defer security to SSH.
All we need to do on the client is to port-forward the TurboVNC port and connect:
client% ssh <server> -L 5930:localhost:5930
client% vncviewer -securitytypes none :30 -DesktopSize=2500x1350 -Scale=150&Here I’m setting a size and a scale manually, but you get the idea.
The X server started by TurboVNC is very bare, but one can start a terminal manually and then go from there:
server% DISPLAY=:30 xfce-terminal&I use openbox for simple window management, by just starting it from the terminal spawned above.