run apps using audio in a docker container - qt

Question

This question is inspired by Can you run GUI apps in a docker container?.
The basic idea is to run apps with audio and ui (vlc, firefox, skype, ...)
I was searching for docker containers using pulseaudio but all containers I found where using pulseaudio streaming over tcp.
(security sandboxing of the applications)
https://gist.github.com/hybris42/ce429de428e5af3a344a
https://github.com/jlund/docker-chrome-pulseaudio
https://github.com/tomparys/docker-skype-pulseaudio
In my case I would prefere playing audio from an app inside the container directly to my host pulseaudio. (without ssh tunneling and bloated docker images)
Pulseaudio because my qt app is using it ;)

Answer 1

it took me some time until i found out what is needed. (Ubuntu)
we start with the docker run command docker run -ti --rm myContainer sh -c "echo run something"
ALSA:
we need /dev/snd and some hardware access as it looks like.
when we put this together we have
docker run -ti --rm \
-v /dev/snd:/dev/snd \
--lxc-conf='lxc.cgroup.devices.allow = c 116:* rwm' \
myContainer sh -c "echo run something"`
In new docker versions without lxc flags you shoud use this:
docker run -ti --rm \
-v /dev/snd:/dev/snd \
--privileged \
myContainer sh -c "echo run something"`
PULSEAUDIO:
update: it may be enought to mount the pulseaudio socket within the container using -v option. this depends on your version and prefered access method. see other answers for the socket method.
Here we need basically /dev/shm, /etc/machine-id and /run/user/$uid/pulse. But that is not all (maybe because of Ubuntu and how they did it in the past). The envirorment variable XDG_RUNTIME_DIR has to be the same in the host system and in your docker container. You may also need /var/lib/dbus because some apps are accessing the machine id from here (may only containing a symbolic link to the 'real' machine id). And at least you may need the hidden home folder ~/.pulse for some temp data (i am not sure about this).
docker run -ti --rm \
-v /dev/shm:/dev/shm \
-v /etc/machine-id:/etc/machine-id \
-v /run/user/$uid/pulse:/run/user/$uid/pulse \
-v /var/lib/dbus:/var/lib/dbus \
-v ~/.pulse:/home/$dockerUsername/.pulse \
myContainer sh -c "echo run something"
In new docker versions you might need to add --privileged.
Of course you can combine both together and use it together with xServer ui forwarding like here: https://stackoverflow.com/a/28971413/2835523
Just to mention:
you can handle most of this (all without the used id) in the dockerfile
using uid=$(id -u) to get the user id and gid with id -g
creating a docker user with this id
create user script:
mkdir -p /home/$dockerUsername && \
echo "$dockerUsername:x:${uid}:${gid}:$dockerUsername,,,:/home/$dockerUsername:/bin/bash" >> /etc/passwd && \
echo "$dockerUsername:x:${uid}:" >> /etc/group && \
mkdir /etc/sudoers.d && \
echo "$dockerUsername ALL=(ALL) NOPASSWD: ALL" > /etc/sudoers.d/$dockerUsername && \
chmod 0440 /etc/sudoers.d/$dockerUsername && \
chown ${uid}:${gid} -R /home/$dockerUsername

Answer 2

Inspired by the links you've posted, I was able to create the following solution. It is as lightweight as I could get it. However, I'm not sure if it is (1) secure, and (2) entirely fits your use-case (as it still uses the network).
Install paprefson your host system, e.g. using sudo apt-get install paprefs on an Ubuntu machine.
Launch PulseAudio Preferences, go to the "Network Server" tab, and check the "Enable network access to local sound devices" checkbox [1]
Restart your computer. (Only restarting Pulseaudio didn't work for me on Ubuntu 14.10)
Install Pulseaudio in your container, e.g. sudo apt-get install -y pulseaudio
In your container, run export "PULSE_SERVER=tcp:<host IP address>:<host Pulseaudio port>". For example, export "PULSE_SERVER=tcp:172.16.86.13:4713" [2]. You can find out your IP address using ifconfig and the Pulseaudio port using pax11publish [1].
That's it. Step 5 should probably be automated if the IP address and Pulseaudio port are subject to change. Additionally, I'm not sure if Docker permanently stores environment variables like PULSE_SERVER: If it doesn't then you have to initialize it after each container start.
Suggestions to make my approach even better would be greatly appreciated, since I'm currently working on a similar problem as the OP.
References:
[1] https://github.com/jlund/docker-chrome-pulseaudio
[2] https://github.com/jlund/docker-chrome-pulseaudio/blob/master/Dockerfile
UPDATE (and probably the better solution):
This also works using a Unix socket instead of a TCP socket:
Start the container with -v /run/user/$UID/pulse/native:/path/to/pulseaudio/socket
In the container, run export "PULSE_SERVER=unix:/path/to/pulseaudio/socket"
The /path/to/pulseaudio/socket can be anything, for testing purposes I used /home/user/pulse.
Maybe it will even work with the same path as on the host (taking care of the $UID part) as the default socket, this way the ultimate solution would be -v /run/user/$UID/pulse/native:/run/user/<UID in container>/pulse; I haven't tested this however.

Answer 3

After trying most of the solutions described here I found only PulseAudio over network to be really working. However you can make it safe by keeping the authentication.
Install paprefs (on host machine):
$ apt-get install paprefs
Launch paprefs (PulseAudio Preferences) > Network Server > [X] Enable network access to local sound devices.
Restart PulseAudio:
$ service pulseaudio restart
Check it worked or restart machine:
$ (pax11publish || xprop -root PULSE_SERVER) | grep -Eo 'tcp:[^ ]*'
tcp:myhostname:4713
Now use that socket:
$ docker run \
-e PULSE_SERVER=tcp:$(hostname -i):4713 \
-e PULSE_COOKIE=/run/pulse/cookie \
-v ~/.config/pulse/cookie:/run/pulse/cookie \
...
Check that the user running inside the container has access to the cookie file ~/.config/pulse/cookie.
To test it works:
$ apt-get install mplayer
$ mplayer /usr/share/sounds/alsa/Front_Right.wav
For more info may check Docker Mopidy project.

Answer 4

Assuming pulseaudio is installed on host and in image, one can provide pulseaudio sound over tcp with only a few steps. pulseaudio does not need to be restarted, and no configuration has to be done on host or in image either. This way it is included in x11docker, without the need of VNC or SSH:
First, find a free tcp port:
read LOWERPORT UPPERPORT < /proc/sys/net/ipv4/ip_local_port_range
while : ; do
PULSE_PORT="`shuf -i $LOWERPORT-$UPPERPORT -n 1`"
ss -lpn | grep -q ":$PULSE_PORT " || break
done
Get ip adress of docker daemon. I always find it being 172.17.42.1/16
ip -4 -o a | grep docker0 | awk '{print $4}'
Load pulseaudio tcp module, authenticate connection to docker ip:
PULSE_MODULE_ID=$(pactl load-module module-native-protocol-tcp port=$PULSE_PORT auth-ip-acl=172.17.42.1/16)
On docker run, create environment variable PULSE_SERVER
docker run -e PULSE_SERVER=tcp:172.17.42.1:$PULSE_PORT yourimage
Afterwards, unload tcp module. (Note: for unknown reasons, unloading this module can stop pulseaudio daemon on host):
pactl unload-module $PULSE_MODULE_ID
Edit: How-To for ALSA and Pulseaudio in container

Answer 5

I managed to dockerize a Java game in the following ways, effectively passing through the game's sound.
This approach requires building an image, making sure the app has all the dependencies it'll need, in this case, pulseaudio and x11. If you're sure your images has everything it needs, you may procees as stated in the previous answers.
Here, we need to build the image, then we can actually launch it.
docker build -t my-unciv-image . # Run from directory where Dockerfile is
docker run --name unciv # image name\
--device /dev/dri \
-e DISPLAY=$DISPLAY \
-e PULSE_SERVER=unix:/run/user/1000/pulse/native \
--privileged \
-u $(id -u):$(id -g) \
-v /path/to/Unciv:/App \
-v /run/user/$(id -u)/pulse:/run/user/(id -u)/pulse \
-v /tmp/.X11-unix:/tmp/.X11-unix \
-w /App \
my-unciv-image \
java -jar /App/Unciv.jar
In the second command the following is specified:
--name: a name is given to the container
--device: video device*
-e: required environment vars
DISPLAY: the display number
PULSE_SERVER: PulseAudio audio server socket
--privileged: run ip privileged*, so it can access all devices
-v: Mounted volumes:
Path to the game mounted into /App in the container**
Audio server socke
Display server socket
-w: Working directory
Here is a docker-compose.yml version of it:
# docker-compose.yml
version: '3'
services:
unciv:
build: .
container_name: unciv
devices:
- /dev/dri:/dev/dri # * Either this
entrypoint: java -jar /App/Unciv.jar
environment:
- DISPLAY=$DISPLAY
- PULSE_SERVER=unix:/run/user/1000/pulse/native
privileged: true # * or this
user: 1000:1000
volumes:
- /path/to/game/:/App
- /run/user/1000/pulse:/run/user/1000/pulse
- /tmp/.X11-unix:/tmp/.X11-unix
working_dir: /App
FROM ubuntu:20.04
RUN apt-get update
RUN apt-get install openjdk-11-jre -y
RUN apt-get install -y xserver-xorg-video-all
RUN apt-get install -y libgl1-mesa-glx libgl1-mesa-dri
RUN apt-get install -y pulseaudio
USER unciv
Notes:
*Only required for a game or anything that uses openGL. Either passing the devices explicitly or running it as privileged, but I think it's enough to pass the device, making it privileged may be overkill.
**This math may be bundled with the docker image, but for a demo.
For the audio, it's required to pass env variable PULSE_SERVER and mounting the pulseaudio socket