Automatic versioning through a Maven repository

[CLOVIS-AI]

Is your feature request related to a problem? Please describe

Dokka offers the Versioning plugin to allow displaying multiple versions of the documentation in a single website. This is great, however setting it up is a bit complex and inconvenient, in particular because it requires having access to previously-built artifacts, which are usually not easy to access through a CI pipeline.

Describe the solution you'd like

An idiomatic library deployment to MavenCentral includes a documentation artifact (the traditional -javadoc JAR). Therefore, we can use MavenCentral as the source of previous versions' documentation.

It would be great to add an option to the Versioning plugin, like autoDownloadPreviousVersionsFromMaven.set(true) or similar, that would download previous versions of each module's documentation from its previous published versions on Central or another Maven repository that has documentation artifacts.

Describe alternatives you've considered

Apollo GraphQL has a custom convention plugin that does something like this. However, it seems to require publishing the documentation to a different coordinate rather than use each artifact's already published documentation. Also, it is very ad-hoc, whereas I believe this feature should be upstreamed to benefit everyone using Dokka.

[martinbonnin]

it seems to require publishing the documentation to a different coordinate rather than use each artifact's already published documentation

Indeed it does. I believe the main issue is that the versioning plugin requires the "multi-module" HTML files and I haven't found a way to reconstruct that from individual modules kdoc.

My favourite solution would be to publish an "IR-like", machine-readable kdoc zip alongside each module instead of HTML (See also #621, #1298, #2787). Then the HTML conversion step could take each module data and reconstruct a multi-version, multi-module documentation.

That'd mean any styling change would apply to older versions retro-actively. That also means the "IR" needs to be somewhat stable so that older "IRs" can be read with newer dokka.