Docker – Setup Container to Communicate with Host Over D-Bus

d-busdocker

I'm creating two apps, master and slave, which communicate over d-bus. My apps work as expected when being run on the same host.
Now I want to move slave app to docker container and I'm having problem sharing d-bus session between host and container. Here's my Dockerfile:

FROM i386/ubuntu:16.04

VOLUME /run/user/1000/
ENV DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus

RUN apt-get update
RUN apt-get upgrade -y
RUN apt-get install -y dbus

#RUN apt-get install -y libnotify-bin
#RUN apt-get install -y dbus-x11

RUN adduser -u 1000 myuser

#COPY dbus.conf /etc/dbus-1/session.d/

USER 1000:1000
ENTRYPOINT ["dbus-daemon", "--session", "--print-address"]

/run/user/1000/bus is the value of my DBUS_SESSION_BUS_ADDRESS variable.

And i create container with

 docker create --mount type=bind,source=/run/user/1000/bus,target=/run/user/1000/bus mycontainer

/run/user/1000/bus is visible from within the container but when the container is started it prints the address 

unix:abstract=/tmp/dbus-iXrYzptYOX,guid=78a790f0f6a4387a39ac3d505da478a3

and my apps cannot communicate.

If i add my dbus.conf to /etc/dbus-1/session.d/ in container and override 

 <listen>unix:path=/run/user/1000/bus</listen>

I get the message 'Failed to start message bus: Failed to bind socket "/run/user/1000/bus": Address already in use'

I'm not sure whether I'm even supposed to be starting dbus-daemon inside docker.
How can I make this work?

Best Answer

I've found a solution. Here's my Dockerfile:

FROM i386/ubuntu:16.04

RUN apt-get update
RUN apt-get upgrade -y
RUN apt-get install -y dbus

COPY dbus.conf /etc/dbus-1/session.d/

ENTRYPOINT ["dbus-run-session", "slaveApp"]

And my dbus.conf:

<!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-Bus Bus Configuration 1.0//EN"
    "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">

<busconfig>
    <listen>tcp:host=localhost,bind=*,port=6667,family=ipv4</listen>
    <listen>unix:tmpdir=/tmp</listen>
    <auth>ANONYMOUS</auth>
    <allow_anonymous/>
</busconfig>

And set the address variable on host:

export DBUS_SESSION_BUS_ADDRESS=tcp:host=${containerIp},port=6667,family=ipv4

In my master app I initiate a connection (I used Qt):

 QDBusConnection::connectToBus("tcp:host=${containerIp},port=6667", "qt_default_session_bus");

The master app can now send messages to slave app. I haven't tried to send messages from slave to master, though.

The answer is taken from this post: https://stackoverflow.com/a/45487266/6509266

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