Allow mounting jupyterlite content

[martinRenou]

cc. @trungleduc @DerThorsten @jtpio

This allows optionally mounting the jupyterlite content into the kernel.

• It is disabled by default, not changing the behavior of the kernel
• It is enabled by default if only generating a voici output

[martinRenou]

What's remaining in this PR:

If /files/ is an existing directory at runtime, we should have the kernel cd into that directory automatically, providing a smooth experience to the user

[jtpio]

needs a corner case in Voici for when jupyterlite-xeus addon is there)

Or maybe the other way around? The jupyterlite-xeus addon checking if it is a voici build. So all this logic stays in the place?

[martinRenou]

Right! I'll check how to do that.

We may want to let the user overwrite this behavior if needed.

[jtpio]

Does it completely bypass, or does it provide a way to bundle additional files at build time?

[jtpio]

Answering my own question after checking the code below: it does seem to bypass:

if (await this._remote.isDir('/files')) {
    await this._remote.cd('/files');
} else if (options.mountDrive) {
    await this._remote.cd(localPath);
}

[jtpio]

Maybe something we could add to the docs once we have #17.

[martinRenou]

Does it completely bypass, or does it provide a way to bundle additional files at build time?

You can still provide extra mount points 👍🏽 It's just that now jupyterlite-xeus has an extra mount point /files that contains the jupyterlite content.

Answering my own question after checking the code below: it does seem to bypass:

No it does not. The service worker is still enabled. So if you do an os.chdir into the mount point of the service worker based filesystem, you'd be using that.

The code you pointed to is only changing the cwd from where the kernel is starting.

[martinRenou]

Indeed it would be nice to clarify all this in proper documentation

[martinRenou]

@jtpio I updated the description to be a bit more clear

[jtpio]

ah ok, thanks for the extra context 👍

[jtpio]

Thanks!

[martinRenou]

Thank you! Let's work on some proper documentation