Tag Archives: RHEL7

Run any application on RHEL7 containerized with 3D acceleration and pulseaudio ( Steam, Pidgin, VLC, …)

Red Hat Enterprise Linux 7 RC was released some time ago. Since the beta was already quite decent I wanted to toy around with the RC version.

My setup is quite unique. My root filesystem is on ZFS which I used on archlinux. Since I didn’t want to reinstall my laptop I just created another ZFS filesystem and manually bootstrapped RHEL7 with the RPMs from ftp://ftp.redhat.com and the version of yum which can be found in the archlinux user repository.
I will not go into the specifics of that though.

The overall experience with RHEL7 has been great so far. But I was missing some applications like Pidgin ( which has been removed in favour of Telepathy ), Steam and VLC.
Since I know my way around systemd, thanks to archlinux and Fedora I knew about systemd-nspawn.
It’s a tool to enable lightweight containerisation of single applications or booting whole Linux distributions in their own namespace.

So getting the Pidgin from my archlinux install running was quite easy.
sudo systemd-nspawn -M pidgin --bind=/home:/home -D /altroot/ARCH-ROOT su maci -c 'DISPLAY=:0 pidgin' &

Another great way to run applications in containers is Docker.
Docker has a great index of pre-built images to start applications in containers.
There even is an image to run Steam inside of a SteamOS environment. https://index.docker.io/u/tianon/steam/
In theory a simple docker run tianon/steam should be sufficient to boot up steam.
However Steam needs access to the hosts X server. So we need to bind-mount /tmp/.X11-unix into the docker container. Docker has a command line option for that -v its the equivalent to systemd-nspawn‘s --bind.
Now the Steam interface starts up just fine. There is no audio output though.
It took me some time to get the audio output working since the pulseaudio FAQ is quite outdated, it lists a bunch of bind mounts required to get audio working inside a chroot environment.
In reality what we do need is /run/user/${UID}/pulse, /etc/machine-id and /dev/shm.

Now we got graphical output and sound, but the 3D acceleration is not working.
It’s easy to get it working though. First make sure the OS image you use has the opengl libs for your physical video card, in the steam container the mesa libs are pre-installed, next bind mount /dev/dri into your container.

Update 2015-10-04: For some reason the image does not work out of the box anymore, I will investigate.

All combined we get something like:
docker run --name=steam \
-v /dev/dri:/dev/dri \
-v /tmp/.X11-unix:/tmp/.X11-unix -v /dev/shm:/dev/shm \
-v /run/user/${UID}/pulse:/run/user/${UID}/pulse \
-v /etc/machine-id:/etc/machine-id \
-v ${HOME}/Downloads:/tmp/Downloads \
-e DISPLAY=${DISPLAY} tianon/steam

Further information about the parameters can be found in the docker documentation.

That’s all. Using the methods described above you can get almost every application working in a container. VLC for example with systemd-nspawn
sudo systemd-nspawn --bind /tmp/.X11-unix:/tmp/.X11-unix \
--bind=/dev/shm:/dev/shm --bind=/dev/dri:/dev/dri \
--bind=/run/user/${UID}/pulse:/run/user/${UID}/pulse \
--bind=/etc/machine-id:/etc/machine-id \
-D /altroot/ARCH-ROOT \
su vlc -c "DISPLAY=:0 QT_X11_NO_MITSHM=1 dbus-launch /usr/bin/vlc --no-qt-privacy-ask"

Other ideas for applications you can run in a container: firefox, keepassX or basically every desktop application you want to separate from the system.
But you should remember to only bind-mount those resources into the container which are mandatory for your application to work.