Running GUI in docker (no ssh, no VNC) - docker

Question

TL;DR: root is not supposed to run GUI app, set a regular user to do so.
I'm trying to run arduino IDE (downloaded, not the package) from within a Docker. I wrote the Dockerfile as follow:
FROM ubuntu:14.04
MAINTAINER Mael Auzias <docker#mael.auzias.net>
ENV HOME /home/arduino
ENV USER arduino
RUN apt-get update && apt-get install -y \
libx11-6 libxext-dev libxrender-dev libxtst-dev \
--no-install-recommends \
&& useradd --create-home --home-dir $HOME $USER \
&& chown -R $USER:$USER $HOME
ADD arduino-1.6.6-linux64.tar.xz $HOME
WORKDIR $HOME/arduino-1.6.6
USER $USER
ENTRYPOINT ["/bin/bash"]
I spent time to understand how does Jessica Frazelle usually starts her graphical containers to rightly start mine with the command:
$docker run --name arduino --rm -it -e DISPLAY=$DISPLAY -v /tmp/.X11-unix:/tmp/.X11-unix 25af73b6cb3c ./arduino
No protocol specified
Picked up JAVA_TOOL_OPTIONS:
No protocol specified
Exception in thread "main" java.awt.AWTError: Can't connect to X11 window server using ':0' as the value of the DISPLAY variable.
I installed strace and check with xeyes what was wrong, and I get the following error:
connect(3, {sa_family=AF_LOCAL, sun_path=#"/tmp/.X11-unix/X0"}, 20) = -1 ECONNREFUSED (Connection refused)
Did anyone experience this? Can any point me out some doc or see what I'm doing wrong?
Any help would be welcome.
PS: as specified in the title I do not want to use ssh or VNC. No cryptography should be used nor network when a unix socket is faster and enough.
Solution
Got some news...
As the user root I cannot start graphical application. When I su regular-user and start xterm or xeyes it works. I don't really understand why though :/
Here is the working Dockerfile, tested on Fedora 23.
The application must not be ran as root so it starts using X.
Note that, unrelated to this issue, a Java option has been removed from the bash file arduino (so it starts properly).
After a docker build -t arduino-1.6.6 ., docker run --name arduino --rm -it -e DISPLAY=$DISPLAY -v /tmp/.X11-unix:/tmp/.X11-unix arduino-1.6.6 ./arduino start the arduino IDE.
You will not be able to upload any code into an arduino without adding a --device or -v to share the /dev/ttyUSB0.
FROM ubuntu:14.04
MAINTAINER Mael Auzias <docker#mael.auzias.net>
ENV HOME /home/arduino
ENV USER arduino
RUN apt-get update && apt-get install -y \
libx11-6 libxext-dev libxrender-dev libxtst-dev \
--no-install-recommends \
&& rm -rf /var/lib/apt/lists/* \
&& useradd --create-home --home-dir $HOME $USER \
&& chown -R $USER:$USER $HOME
ADD arduino-1.6.6-linux64.tar.xz $HOME
RUN sed -i 's/"-Dswing.defaultlaf=com.sun.java.swing.plaf.gtk.GTKLookAndFeel"//g' /home/arduino/arduino-1.6.6/arduino
WORKDIR $HOME/arduino-1.6.6
USER $USER
ENTRYPOINT ["/bin/bash"]

Answer 1

Got some news...
As the user root I cannot start graphical application. When I su regular-user and start xterm or xeyes it works. I don't really understand why though :/
Here is the working Dockerfile, tested on Fedora 23.
The application must not be ran as root so it starts using X.
Note that, unrelated to this issue, a Java option has been removed from the bash file arduino (so it starts properly).
After a docker build -t arduino-1.6.6 ., docker run --name arduino --rm -it -e DISPLAY=$DISPLAY -v /tmp/.X11-unix:/tmp/.X11-unix arduino-1.6.6 ./arduino start the arduino IDE.
You will not be able to upload any code into an arduino without adding a --device or -v to share the /dev/ttyUSB0.
FROM ubuntu:14.04
MAINTAINER Mael Auzias <docker#mael.auzias.net>
ENV HOME /home/arduino
ENV USER arduino
RUN apt-get update && apt-get install -y \
libx11-6 libxext-dev libxrender-dev libxtst-dev \
--no-install-recommends \
&& rm -rf /var/lib/apt/lists/* \
&& useradd --create-home --home-dir $HOME $USER \
&& chown -R $USER:$USER $HOME
ADD arduino-1.6.6-linux64.tar.xz $HOME
RUN sed -i 's/"-Dswing.defaultlaf=com.sun.java.swing.plaf.gtk.GTKLookAndFeel"//g' /home/arduino/arduino-1.6.6/arduino
WORKDIR $HOME/arduino-1.6.6
USER $USER
ENTRYPOINT ["/bin/bash"]