New module will have to be made for that use case. something like `service.xpra.enable`, these are two different use cases. One is display manager and other is xpra that attaches to existing display manager. While this is not really use case I have, i can help with development of such module. Driver cannot be found for xdummy, because xorg config with path to driver has to be passed to xdummy. In most other distros it's somewhere under /etc. On Wed, 5 Apr 2017, 20:01 Victor Calvert, <notifications@github.com> wrote: Issue description My use case: I have a desktop X environment that I am happy with (slim autologin + xmonad). I am also on remote systems (e.g. laptop), and want to be able to share certain program instances between the two at times. For example, a web browser or LibreOffice session, graphical IRC client, etc. - basically anything that does not use 3D acceleration or video playback. I want to be able to SSH into the server or open a terminal, and do the following: $ xpra start :10 $ DISPLAY=:10 ${CMD} & disown This sets up an application that I'm interested in using. I can then connect to the xpra server to use the applications via one of the following commands: $ xpra attach ssh:<hostname>:10 # remote access $ xpra attach :10 # local access Yes, it would be nice to auto-start some of this, but that's relatively straightforward to implement. The problem: - I can add xpra to environment.systemPackages; this installs fine. - If the server command is overridden to use the Xvfb variant provided in the config file, this works. - It *does not* work on NixOS with xpra_Xdummy. The logs indicate that it cannot find the dummy driver. @offlinehacker <https://github.com/offlinehacker> mentioned the xpra.nix module in this context on #24644 <#24644>. This functionality is something I hadn't noticed before, but If I'm following correctly, I can't have a machine host both a desktop X environment and xpra while using the Xorg server. Specifically, xpra is set up as a displayManager, and if I understand correctly, only one displayManager can be enabled on a NixOS system. There are actually multple use cases for xpra: It is effectively a combination of display manager and window manager, in that it can provide forwarding for entire desktops (display manager case) or for applications (window manager case). Steps to reproduce I have services.xserver.displayManager.slim.enable=true in my configuration.nix. If I add services.xserver.displayManager.xpra.enable=true without disabling slim, I get the following error on rebuild attempts: error: The unique option `services.xserver.displayManager.job.execCmd' is defined multiple times, in `.../nixpkgs/nixos/modules/services/x11/display-managers/xpra.nix' and `.../nixpkgs/nixos/modules/services/x11/display-managers/slim.nix'. (use ‘--show-trace’ to show detailed location information) Disabling slim is not an acceptable solution as I need the desktop X environment... Technical details - System: 17.09.git.6b5e5de (Hummingbird) - Nix version: nix-env (Nix) 1.11.8 - Nixpkgs version: "17.09.git.6b5e5de0ef" — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#24652>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAjvS8pQqXk7S2Vr6M-QfRfDTag1MU3hks5rs9cEgaJpZM4M0mo9> .

The latter is my usecase as well. I was trying to figure out how to use xpra in nixos with an existing display manager and I couldn't get it working, I ran into the same issues. 👍 for a `service.xpra`. Thanks if you get around to adding this!