[enhancement] a few suggestions

[MartinaRuocco]

Hi!

I'm sorry if this might be a silly question (I'm new to Docker) but what do you mean by

Before entering the python interpreter, a script to attach the graphical display should have been run.

? Can you provide an example, please?

[TTitcombe]

No that's my fault - it's not worded very well. You don't have to do anything for that line in the documentation.

What that was saying is that it's possible to configure a dockerfile to execute something in a container before the container actually starts. The last line in the Dockerfile does this: ENTRYPOINT ["/usr/local/bin/startup_script.sh"]

This means that when you run the command to run the container and enter the interpreter this script will run (I said "should" because I didn't know Docker very well when I wrote this, so wasn't 100% confident). That script makes the graphical display work.

[MartinaRuocco]

Alright, thanks @TTitcombe!

• At this point it is worth mentioning that I had to do some changes to your Dockerfile, adding "sh" as an argument to the ENTRYPOINT: ENTRYPOINT ["sh","/usr/local/bin/startup_script.sh"] The reason is that it gave me this error standard_init_linux.go:219: exec user process caused: no such file or directory when launching the container (step 2 of your README).
• I guess in step 4 and 5 you meant to write /usr/local/bin/startup_script.sh and not /usr/local/bin/startup_script.py... am I correct?
• [testing phase] I suggest you integrate what you wrote in your (very good) medium article with the info on how to use your python script to test the container:
  1. comment the line shutil.rmtree(file_path) in tests/test_image.py
  2. in a new terminal: docker cp tests/test_image.py test_container:/tmp/test_image.py docker exec -it test_container /usr/local/bin/startup_script.sh "python /tmp/test_image.py"
docker cp test_container:/rec/video ~/Desktop/

It's worth mentioning that at the time I am writing this comment, there is a bug in the video_recording.py script of the gym library that I solved by modifying it.
For future reference, whoever wants to modify an image can follow this guide. In summary:

1. run the container docker run -it test_container old-image-name bash
2. From the shell, make the changes in the container as required (in this case, I modified the video_recording.py script). Once done, exit the container.
3. from a new terminal docker commit test_container new-image-name