Screensharing

This guide is specifically for getting Wayland screensharing to work using xdg-desktop-portal-hyprland. It won’t contain any steps or instructions on how to install Incus/LXD, get X11/Wayland working, or passthrough audio.

Please refer to the references or find guides online.

TL;DR Incus Config

config:
  boot.autostart: false
  cloud-init.vendor-data: |
    #cloud-config
    users:
      - name: chicken
        groups: wheel, video
        sudo: ['ALL=(ALL) NOPASSWD:ALL']
    runcmd:
    - chown -R chicken:chicken /home/chicken/
    write_files:
      - path: /etc/profile
        append: true
        content: |
          mkdir -p /run/user/1000
          chown chicken:chicken /run/user/1000
          ln -sf /mnt/.sockets/X0 /tmp/.X11-unix/X0
          ln -sf /mnt/.sockets/bus /run/user/1000/bus
          ln -sf /mnt/.sockets/pipewire-0 /run/user/1000/pipewire-0
          ln -sf /mnt/.sockets/wayland-1 /run/user/1000/wayland-1
          export DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus
          export DISPLAY=:0
          export QT_QPA_PLATFORM=wayland
          export WAYLAND_DISPLAY=wayland-1
          export XDG_CURRENT_DESKTOP=Hyprland
          export XDG_RUNTIME_DIR=/run/user/1000
          export XDG_SESSION_TYPE=wayland

description: Screensharing Tutorial
devices:
  dbus:
    path: /run/dbus/system_bus_socket
    shift: "true"
    source: /run/dbus/system_bus_socket
    type: disk
  dbus_session:
    path: /mnt/.sockets/bus
    shift: "true"
    source: /run/user/1000/bus
    type: disk
  graphics:
    gid: "1000"
    type: gpu
    uid: "1000"
  wayland:
    path: /mnt/.sockets/wayland-1
    shift: true
    source: /run/user/1000/wayland-1
    type: disk
  xwayland:
    path: /mnt/.sockets/X0
    shift: "true"
    source: /tmp/.X11-unix/X0
    type: disk
  pipewire:
    path: /mnt/.sockets/pipewire-0
    shift: true
    source: /run/user/1000/pipewire-0
    type: disk

Prerequisites

This guide is specifically for my own setup. However, it’s possible to change the environment used since the overall idea is the same.

Prerequisites:

  • Hyprland as host desktop environment

  • pipewire for audio passthrough

  • Wayland/X11 passthrough

  • xdg-desktop-portal-hyprland for screensharing

  • DBUS for screensharing

Once the basic setup of audio + wayland/x11 passthrough is working, there is a need to passthrough DBUS as well for pipewire to work.

DBUS Sockets and Session Passthrough

Locating Sockets and Sessions

Look for the file system_bus_socket and bus.

Make sure the host have the necessary DBUS packages installed.

Paths for the files:

Socket
/run/dbus/system_bus_socket
Session
/run/user/1000/bus

The location of the session is dependent on the user id. To find the user id, simply run id command.

Adding to Devices

Next is add the DBUS paths to the profile in devices.

devices:
  dbus:
    path: /run/dbus/system_bus_socket
    shift: "true"
    source: /run/dbus/system_bus_socket
    type: disk
  dbus_session:
    path: /mnt/.sockets/bus
    shift: "true"
    source: /run/user/1000/bus
    type: disk

Take note of the path since it will be used to symlink it later in the container. The path does not necessarily have to be in /mnt but I noticed that the config fails to passthrough the file or directory when it’s directly placed on /run. Other people places their path on /tmp. Do what you prefer and what works.

Although I haven’t tested if either one works but maybe if some experiments with the configuration, either the socket or sesssion may not be needed.

Generating Symlink and Environment Variables

Create a consistent symlink to /run/dbus/system_bus_socket and /run/user/1000/bus by updating /etc/profile. Because sometimes cloud-init fails to configure the profile config.

write_files:
  - path: /etc/profile
    append: true
    content: |
      mkdir -p /run/user/1000
      chown chicken:chicken /run/user/1000
      ln -sf /mnt/.sockets/bus /run/user/1000/bus
      export DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus
      export WAYLAND_DISPLAY=wayland-1
      export XDG_CURRENT_DESKTOP=Hyprland

I didn’t include the other symlinks and environment variables because I wanted to only show the necessary ones for screensharing to work.

Notice that I didn’t symlink /run/dbus/system_bus_socket, it’s because for some reason this works. Unlike the directory 1000.

There is also a need to export the DBUS_SESSION_BUS_ADDRESS to tell DBUS where the current session path is located. Export its value to the path of bus with prefix unix:path=.

Environment variable of bus
unix:path=/run/user/1000/bus

Export XDG_CURRENT_DESKTOP and WAYLAND_DISPLAY. These two must be present in order for xdg-desktop-portal and xdg-desktop-portal-hyprland to run.

Here’s a note from Arch Wiki regarding portals not starting.

Portal Does Not Start
XDG_CURRENT_DESKTOP has to be set to the name of your compositor, e.g. XDG_CURRENT_DESKTOP=sway. WAYLAND_DISPLAY is set automatically by the compositor.

Getting Xauthority

Currently, the configuration isn’t enough to run DBUS session since this error occurs.

Authorization required, but no authorization protocol specified

But it can be fixed by getting xhost on to the host running it.

Solution
xhost +local:

Running Screenshare

I use firefox as my main web browser and often times chromium.

To run with screensharing capabilities, execute dbus-run-session.

$ dbus-run-session firefox
$ dbus-run-session chromium

Then test screensharing on this website.

If it fails, there should be a log in the terminal showing errors for what you have missed or potentially what this guide have missed.

That should be all.

References