Bypass "select kernel" dialog

[chrysn]

Problem

The first interaction I have with a replite instance is always to select a kernel -- even if only one is installed, or when the page author already made a selection. This stops the reading and exercising flow.

Proposed Solution

• If there is just one kernel available, use that.
• Allow the page author to specify the kernel.
  [edit, added:] There is a kernel configuration parameter as demo'd at https://jupyterlite-sphinx.readthedocs.io/en/stable/directives/replite.html, but it has no apparent effect there.

Additional context

I'm looking into using jupyterlite-sphinx for aiocoap's documentation, which currently has a lot of Python examples just in plain text, but I'd love to show off how the library works well with Jupyter already live to the user, possibly even making the guided tour fully exercisable in the browser.

[mfisher87]

From my reading of the docs, I believe this functionality needs to be implemented upstream in JupyterLite before we can support it in jupyterlite-sphinx. @martinRenou does that sound right?

[chrysn]

It is supported in JupyterLite as a query parameter:

• No prompt: https://jupyterlite-pyodide-kernel.readthedocs.io/en/latest/_static/repl/index.html?kernel=python
• Same prompt: https://jupyterlite-pyodide-kernel.readthedocs.io/en/latest/_static/repl/index.html

For the concrete example of https://jupyterlite-sphinx.readthedocs.io/en/stable/directives/replite.html, maybe the documentation just has a wrong kernel value: Placing xpython rather than xeus-python in the argument seems to already do the right thing.

(Something that might be relevant to add upstream is to have some kernel=auto parameter, or if that's default, kernel=ask to explicitly show the popup, but probably this can be fixed in documentation by giving concrete values and examples for kernel.)