Docker container audio output to Libreelec

Is it possible for Docker containers to output audio to alsa on Libreelec? I have done a lot of searching and have not seen this question answered directly, but indirectly I see indications that yes it can and no it can't.

If it can is there some kind of reference container that shows the proof of concept?

Is there a work around using pulse audio or some other means?

Thanks all.

Quote from elonesna

Go back to studying the documentation about docker, the --privileged parameter allows access to the hardware and therefore the audio output

Thank you for the reply.

The rest of this post basically answers my original question since today I was able to have success with speaker-test in a container and could hear it from the receiver.

I had found --privileged and used it in prior attempts. It does permit the listing of /proc/asound, but I could not get beyond that.

ls -al /proc/asound

LibreELECWyse:~ # aplay -L

null

Discard all samples (playback) or generate zero samples (capture)

hdmi:CARD=HDMI,DEV=0

HDA ATI HDMI, HDMI 0

HDMI Audio Output

hdmi:CARD=HDMI,DEV=1

HDA ATI HDMI, HDMI 1

HDMI Audio Output

sysdefault:CARD=Generic

HD-Audio Generic, ALC231 Analog

Default Audio Device

front:CARD=Generic,DEV=0

HD-Audio Generic, ALC231 Analog

Front output / input

surround21:CARD=Generic,DEV=0

HD-Audio Generic, ALC231 Analog

2.1 Surround output to Front and Subwoofer speakers

surround40:CARD=Generic,DEV=0

HD-Audio Generic, ALC231 Analog

4.0 Surround output to Front and Rear speakers

surround41:CARD=Generic,DEV=0

I made a docker container to run speaker-test and did get sound output. Dockerfile:

FROM alpine:3.12

RUN apk --no-cache add alsa-utils

CMD [ "sh" ]

LibreELECWyse:~ # docker run --rm --privileged --device /dev/snd aucdb speaker-test -D hdmi:CARD=HDMI,DEV=0 -c 2 -b544000

speaker-test 1.2.2

Playback device is hdmi:CARD=HDMI,DEV=0

Stream parameters are 48000Hz, S16_LE, 2 channels

Using 16 octaves of pink noise

Rate set to 48000Hz (requested 48000Hz)

Buffer size range from 64 to 8544000

Period size range from 32 to 4272000

Requested buffer time 544000 us

Periods = 4

was set period_size = 6528

was set buffer_size = 26112

0 - Front Left

1 - Front Right

Time per period = 5.453585

0 - Front Left

...

Thanks to all.

Now I know that speaker-test works from Docker on Libreelec, I was hoping to get some help getting the shairport-sync-docker container running. I can run it just fine on Debian so I know it works.

I have been working with the author trying get his container to run on Libreelec but have not had any success and just get these errors in the container log. Many combinations have been tried. I think it comes down to linux security and device access.

If anybody has any suggestions things to try differently in the Dockerfile or the Entrypoint start.sh, it would be greatly appreciated.

LibreELECWyse:~ # aplay -l

**** List of PLAYBACK Hardware Devices ****

card 0: HDMI [HDA ATI HDMI], device 3: HDMI 0 [HDMI 0]

Subdevices: 1/1

Subdevice #0: subdevice #0

card 0: HDMI [HDA ATI HDMI], device 7: HDMI 1 [HDMI 1]

Subdevices: 1/1

Subdevice #0: subdevice #0

card 1: Generic [HD-Audio Generic], device 0: ALC231 Analog [ALC231 Analog]

Subdevices: 1/1

Subdevice #0: subdevice #0

docker run -d --rm --restart unless-stopped --privileged --net host --device /dev/snd mikebrady/shairport-sync -a DenSystem -- -d hw:0

docker run -d --rm --restart unless-stopped --privileged --net host --device /dev/snd mikebrady/shairport-sync -a DenSystem -- -d hw:0,3

ALSA lib pcm_hw.c:1829:(_snd_pcm_hw_open) Invalid value for card,

ALSA lib pcm_hw.c:1829:(_snd_pcm_hw_open) Invalid value for card,

From GitHub - mikebrady/shairport-sync-docker: Docker setup for Shairport Sync

Dockerfile for shairport-sync

FROM alpine:3.12 AS builder-base

# General Build System:

RUN apk -U add \

git \

build-base \

autoconf \

automake \

libtool \

dbus \

su-exec \

alsa-lib-dev \

libdaemon-dev \

popt-dev \

mbedtls-dev \

soxr-dev \

avahi-dev \

libconfig-dev \

libsndfile-dev \

mosquitto-dev \

xmltoman

# ALAC Build System:

FROM builder-base AS builder-alac

RUN git clone GitHub - mikebrady/alac: Apple Lossless Codec and Utility with Autotools

WORKDIR alac

RUN autoreconf -fi

RUN ./configure

RUN make

RUN make install

# Shairport Sync Build System:

FROM builder-base AS builder-sps

# This may be modified by the Github Action Workflow.

ARG SHAIRPORT_SYNC_BRANCH=master

COPY --from=builder-alac /usr/local/lib/libalac.* /usr/local/lib/

COPY --from=builder-alac /usr/local/lib/pkgconfig/alac.pc /usr/local/lib/pkgconfig/alac.pc

COPY --from=builder-alac /usr/local/include /usr/local/include

RUN git clone GitHub - mikebrady/shairport-sync: AirPlay audio player. Shairport Sync adds multi-room capability with Audio Synchronisation

WORKDIR shairport-sync

RUN git checkout "$SHAIRPORT_SYNC_BRANCH"

RUN autoreconf -fi

RUN ./configure \

--with-alsa \

--with-dummy \

--with-pipe \

--with-stdout \

--with-avahi \

--with-ssl=mbedtls \

--with-soxr \

--sysconfdir=/etc \

--with-dbus-interface \

--with-mpris-interface \

--with-mqtt-client \

--with-apple-alac \

--with-convolution

RUN make -j $(nproc)

RUN make install

# Shairport Sync Runtime System:

FROM alpine:3.12

RUN apk -U add \

alsa-lib \

dbus \

popt \

glib \

mbedtls \

soxr \

avahi \

libconfig \

libsndfile \

mosquitto-libs \

su-exec \

libgcc \

libgc++

RUN rm -rf /lib/apk/db/*

COPY --from=builder-alac /usr/local/lib/libalac.* /usr/local/lib/

COPY --from=builder-sps /etc/shairport-sync* /etc/

COPY --from=builder-sps /etc/dbus-1/system.d/shairport-sync-dbus.conf /etc/dbus-1/system.d/

COPY --from=builder-sps /etc/dbus-1/system.d/shairport-sync-mpris.conf /etc/dbus-1/system.d/

COPY --from=builder-sps /usr/local/bin/shairport-sync /usr/local/bin/shairport-sync

# Create non-root user for running the container -- running as the user 'shairport-sync' also allows

# Shairport Sync to provide the D-Bus and MPRIS interfaces within the container

RUN addgroup shairport-sync

RUN adduser -D shairport-sync -G shairport-sync

# Add the shairport-sync user to the pre-existing audio group, which has ID 29, for access to the ALSA stuff

RUN addgroup -g 29 docker_audio && addgroup shairport-sync docker_audio

COPY start.sh /

ENTRYPOINT [ "/start.sh" ]

/start.sh code listing:

#!/bin/sh

set -e

rm -rf /var/run/dbus.pid
#mkdir -p /var/run/dbus

dbus-uuidgen --ensure
dbus-daemon --system

avahi-daemon --daemonize --no-chroot

su-exec shairport-sync shairport-sync $@

I have resolved this issue. There were two issues preventing this from working. One was the container was configured to run as a non-root user in start.sh. The second is specifying the correct device name as the default would not work. There apparently is no hardware mixer or I could not find the correct configuration.

#!/bin/sh

#start.sh

set -e

rm -rf /var/run/dbus.pid

#mkdir -p /var/run/dbus

dbus-uuidgen --ensure

dbus-daemon --system

avahi-daemon --daemonize --no-chroot

#su-exec shairport-sync shairport-sync $@ --Does not work

#su-exec root shairport-sync $@ -- Works

shairport-sync $@ # Works

shairport-sync.conf:

...

// Back End Settings

// These are parameters for the "alsa" audio back end.

// For this section to be operative, Shairport Sync must be built with the following configuration flag:

// --with-alsa

alsa =

{

output_device = "hdmi:CARD=HDMI,DEV=0"; // the name of the alsa output device. Use "shairport-sync -h" to discover the names of ALSA hardware devices. Use "alsamix>

// mixer_control_name = "PCM"; // the name of the mixer to use to adjust output volume. If not specified, volume in adjusted in software.

// mixer_device = "HDMI,DEV=0"; //

...

Thanks to all who replied.