How can I use matplotlib.pyplot in a docker container?

I have a certain setting of Python in an docker image named deep. I used to run python code

docker run --rm -it -v "$PWD":/app -w /app deep python some-code.py

For information, -v and -w options are to link a local file in the current path to the container.

However, I can’t use matplotlib.pyplot. Let’s say test.py is

import matplotlib.pyplot as plt
plt.plot([1,2], [3,4])
plt.show()

I got this error.

Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
 File "/usr/lib/python2.7/dist-packages/matplotlib/pyplot.py", line 3147, in plot
   ax = gca()
 File "/usr/lib/python2.7/dist-packages/matplotlib/pyplot.py", line 928, in gca
   return gcf().gca(**kwargs)
 File "/usr/lib/python2.7/dist-packages/matplotlib/pyplot.py", line 578, in gcf
   return figure()
 File "/usr/lib/python2.7/dist-packages/matplotlib/pyplot.py", line 527, in figure
**kwargs)
 File "/usr/lib/python2.7/dist-packages/matplotlib/backends/backend_tkagg.py", line 84, in new_figure_manager
   return new_figure_manager_given_figure(num, figure)
 File "/usr/lib/python2.7/dist-packages/matplotlib/backends/backend_tkagg.py", line 92, in new_figure_manager_given_figure
   window = Tk.Tk()
 File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1818, in __init__
   self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
_tkinter.TclError: no display name and no $DISPLAY environment variable

With solution search, I am having only one solution. I figured out I can do if

$ xauth list
xxxx/unix:0 yyyy 5nsk3hd                                # copy this list
$ docker run --rm -it -v "$PWD":/app -w /app 
             --net=host -e DISPLAY 
             -v /tmp/.X11-unix:/tmp/.X11-unix 
             deep bash

inside-container$ xauth add xxxx/unix:0 yyyy 5nsk3hd    # paste the list
inside-container$ python test.py                        # now the plot works!!

My question is, instead of all those launching bash, setting xauth, and running Python inside container, can I do such setting with docker run so that I can just run the code outside of the container?

I tried

docker run --rm -it -v "$PWD":/app -w /app 
           --net=host -e DISPLAY 
           -v /tmp/.X11-unix:/tmp/.X11-unix 
           -e "xauth add xxxx/unix:0 yyyy 5nsk3hd" 
           deep python test.py

using --entry parameter, but it didn’t work. Please help.

Answer

Interestingly, I found quite nice and thorough solutions in ROS community. http://wiki.ros.org/docker/Tutorials/GUI

For my problem, my final choice is the second way in the tutorial:

docker run --rm -it 
   --user=$(id -u) 
   --env="DISPLAY" 
   --workdir=/app 
   --volume="$PWD":/app 
   --volume="/etc/group:/etc/group:ro" 
   --volume="/etc/passwd:/etc/passwd:ro" 
   --volume="/etc/shadow:/etc/shadow:ro" 
   --volume="/etc/sudoers.d:/etc/sudoers.d:ro" 
   --volume="/tmp/.X11-unix:/tmp/.X11-unix:rw" 
   deepaul python test.python

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Answer