Issue when loading settings from federated extensions

[jtpio]

Description

Currently the JupyterLab app is missing a menu entry to open Notebook 7 in a new browser tab.

Reproduce

On https://jupyterlite.readthedocs.io/en/latest/_static/lab/index.html :

Expected behavior

It should be possible to open Notebook 7 from JupyterLab like with JupyterLite 0.1.x using RetroLab:

But using the existing Notebook 7 extension that adds the following menu entry:

Context

Follow-up to #1019.

[jtpio]

Installing the notebook package and running jupyter lite build correctly includes @jupyter-notebook/lab-extension in jupyter-lite.json:

{
  "extension": "./extension",
  "liteExtension": false,
  "load": "static/remoteEntry.749fd42299b69250a475.js",
  "name": "@jupyter-notebook/lab-extension",
  "style": "./style"
}

The commands are available in the command palette, but the menu and toolbar items are missing:

So there might be a more general issue of loading settings from a federated extension (to be confirmed).

[jtpio]

So there might be a more general issue of loading settings from a federated extension (to be confirmed).

Looking more into it, there does seem to be a more general issue with toolbar items and menu entries (defined via the settings). This is for example reproducible with https://github.com/jupyterlab/extension-examples/tree/main/toolbar-button.

For now not sure if it's related to a upstream change in JupyterLab 4 w.r.t how the settings are loaded. Next step would be confirm that settings based items and menu entries used to work fine in JupyterLite 0.1.0 built on JupyterLab 3.

[jtpio]

Next step would be confirm that settings based items and menu entries used to work fine in JupyterLite 0.1.0 built on JupyterLab 3.

Yes it works fine in 0.1.3:

So this is likely due to a change in JupyterLab 4.0.

[jtpio]

Maybe related to jupyterlab/jupyterlab#14195 ?

[jtpio]

JupyterLab 4 now seems to be expecting all settings to be returned in one call at application startup.

I guess we can work around that in JupyterLite by moving (or just copying) the schemas directories to the single all.json at jupyter lite build (via the federated extensions addon).

Another option would have been to aggregate all the settings from federated extensions at runtime via PageConfig.getOption('federated_extensions'). But there is no metadata that lists all the available settings for a federated extension (no all.json). So it looks we would need to add a build step anyway.

In the future this might be an issue for deployments setups that would like to load extensions from a CDN or other hosts, since these extensions and their settings would not be known by the application at startup.

[bollwyvl]

like to load extensions from a CDN

yeah, i wouldn't worry too much about that case until someone shows up with a concrete issue... there are so many cases of extension code constructing URLs from baseUrl instead of webpack assets/loaders that a large chunk of extensions wouldn't even work, or would fail in mysterious ways.

[jtpio]

This is tracked upstream and would indeed likely require some other changes anyway: jupyterlab/jupyterlab#8866