Simplify and optimize Docker image

[edoardob90]

• Create a simpler Docker image starting from official Jupyter Docker Stacks
• Remove jupyter-repo2docker dependency
• Add GitHub workflow to build & push the image (as before)
• Adjust the Conda environment which is configured from docker/environment.yml

The old workflow has been renamed to .github/workflows/repo2docker.yml and Binder is still supported via the binder/ directory (unchanged).

Also: since Docker provides already the isolation, there's no need to have another virtual environment. All the tutorial dependencies are installed in the base environment, which is automatically configured by the base image.

[yakutovicha]

@edoardob90 do you need a review on this? I could give a hand.

[edoardob90]

@edoardob90 do you need a review on this? I could give a hand.

If you want, you can try to build the container from the Dockerfile. I tested the workflow in the main branch of my fork, and everything seems to work fine. But a double-check is always appreciated 😉

[yakutovicha]

Thanks, @edoardob90, I did a first pass and I would need some clarifications from your side.

[yakutovicha]

This part is a bit tricky. The user should either start the same container (so the readme needs to be updated), or we should mount the folder to the container.

In any case, the readme should be synchronized with the new approach.

[edoardob90]

I think the step is correct and makes sense only when we're building the image via GitHub Actions. The user can still mount the local folder with a local copy of the repository, and nothing changes if the are no mismatches. Otherwise they will have their local repository inside the container.

[edoardob90]

It might be good to create a docker volume, but I have to think about it carefully.

[edoardob90]

I did a bit of research. It seems that those lines are not needed: I added them to make sure to have the repository material inside the container, but:

1. If the user is mounting a local folder with the repository, that's redundant
2. GitHub Codespaces, which can use a prebuilt Docker image to speed up the startup, also clones the repository by default, so the lines are again redundant

If you agree that this is the case, we can remove them and speed up building the image.

[yakutovicha]

I suggest we have a quick chat about this today during the meeting, and then we can decide.

[edoardob90]

Options:

Leave the COPY command

• We will have two copies of the material when using Codespaces: one in /home/jovyan/python-tutorial and another in /workspaces/python-tutorial (clone by default by GitHub)
• Docker image is larger and takes slightly longer to build

Remove COPY

• Users must clone the repository to have the materials available inside the container. On Windows, this means downloading and installing git first (here)
• Change the README accordingly: the bind-mount directory is not /home/jovyan/work but /home/jovyan/python-tutorial