x11 - Running Chromium inside Docker - Gtk: cannot open display: :0

Question

When I try to run chromium inside a docker container I see the following error: Gtk: cannot open display: :0

Dockerfile: (based on https://registry.hub.docker.com/u/jess/chromium/dockerfile)

FROM debian:jessie

# Install Chromium
RUN sed -i.bak 's/jessie main/jessie main contrib non-free/g' /etc/apt/sources.list && 
    apt-get update && apt-get install -y 
    chromium 
    chromium-l10n 
    libcanberra-gtk-module 
    libexif-dev 
    libpango1.0-0 
    libv4l-0 
    pepperflashplugin-nonfree                                                                           
    --no-install-recommends && 
    mkdir -p /etc/chromium.d/

# Autorun x11vnc
CMD ["/usr/bin/chromium", "--no-sandbox", "--user-data-dir=/data"]

build and run:

docker build -t chromium
docker run -e DISPLAY=$DISPLAY -v /tmp/.X11-unix:/tmp/.X11-unix --privileged chromium

and the error:

[1:1:0202/085603:ERROR:browser_main_loop.cc(164)] Running without the SUID sandbox! See https://code.google.com/p/chromium/wiki/LinuxSUIDSandboxDevelopment for more information on developing with the sandbox on.
No protocol specified
[1:1:0202/085603:ERROR:browser_main_loop.cc(210)] Gtk: cannot open display: :0

Answer 1

i don't know much about chromium, but, I did work with X way back when :-) When you tell an X client to connect to :0, what you are saying is connect to port 6000 (or whatever your X server runs on) + 0, or port 6000 in this case. In fact, DISPLAY is IP:PORT (with the +6000 as mentioned above). The X server is running on your host, so, if you set:

DISPLAY=your_host_ip:0

that might work. However, X servers did not allow connections from just any old client, so, you will need to open up your X server. on your host, run

xhost +

before running the docker container. All of this is assuming you can run chromium on your host (that is, an X server exists on your host).