Page-level over-riding of launch button functionality

[choldgraf]

Context

Currently, our launch buttons are configured at the documentation-level. The GitHub repository etc are defined in conf.py and then used in each page.

However, there are some cases where users might want to specify per-page Binder configuration. For example, if a book has notebooks that require many different packages / languages / etc, the author might prefer to define a Binder environment for each in a different branch (or, multiple repositories), and then create different Binder links on each. (cc @acocac)

Proposal

We could make it possible to define page-level over-rides for launch buttons. For example, here might be two page-level over-rides, and each would over-ride the corresponding fields in the docs-level launch: configuration.

launch:
  repository_url: https://github.com/foo/bar
  branch: foo

and on another page:

launch:
  repository_url: https://github.com/foo/bar
  branch: bar

It might be tricky to get the UX right on this, because people probably won't want to duplicate their content, only the environment needed to run that content. So I think this might also depend on:

• Allow to launch from binder with nbgitpuller #282

Tasks and updates

No response