(Temporary) caching cdn handler until we sort out bundling

[maartenbreddels]

(replaces #3)

Issue to solve

For loading js modules, we have to choose a system, either the notebook extension method or the jupyter lab bundling. This new loader (frontend) will be a temporary solution that will 'just work' until we find the proper way to do this. It will try to fetch from <server>/voila/require/module@semver, which at the server will

• try to find the cached version and return that
• if not found will fetch it from a CDN (default is unpkg) and write it to cache

But only for modules in a whitelist (security concern)

Issues:

It will not respect semver, so will never fetch a patched version once it cached a version.

Where cache?

It first tries {prefix}/share/jupyter/voila_cache/{module}/{semver}, and on failure will use the user directory.

[SylvainCorlay]

We may also want to support the use case where all the widgets are in a single bundle like with jupyterlab.

The loading of external bundles could be activated as an opt-in.

There are benefits to both use cases (all in one bundle, and bundles loaded separately). @jasongrout may have an opinion on that.

[jasongrout]

I think it makes a lot of sense to support the local widgets only use case.

[SylvainCorlay]

We started having some in-depth discussions with @maartenbreddels about having a jupyterlab remix as a front-end for this, reusing the jupyterlab extension mechanism etc.

Would love to brainstorm with you about this.

[jasongrout]

Sounds great. Let's talk today or tomorrow.

[astrojuanlu]

Would this help in making the load times a bit faster?

[maartenbreddels]

Yes it would, what you can also do is put e.g. bqplot.js in the voila/static directory for now (If you open the browser dev console you should see it first tries to fetch that file before trying the cdn

[trungleduc]

Closed due to inactivity