Adds applicability support for a new serverless project

[yetanothertw]

Summary

Fixes #1631

The new Serverless Elasticsearch Vector Database project type needs to have an applicability tag equivalent to the other project types (Elasticsearch, Observability, Security).

This project type already has a https://github.com/elastic/docs-content-internal/issues/1534.

The ask

'docs-builder' tooling functionality needs to be amended to allow for the new applicability.

I took at stab at this PR using Cursor (default agent), but am not comfortable at all with the the accuracy/correctness of this proposed solution. So this needs a thorough review from the Docs Engineering team 🙏

Please feel free to update this PR directly.

Details about the changes

Vector Database is a serverless-only, unversioned project type. Unlike Elasticsearch, Observability, and Security — which also exist as Stack solutions — this project type only exists on Elastic Cloud Serverless. That is why it uses the existing serverless versioning system (the same unversioned sentinel as serverless: ga) instead of getting its own versioning ID.

applies_to now has a fourth serverless flavor: vectorbd. Writers can tag serverless.vectordb: ga (or top-level vectordb: ga). Versions are rejected, same as elasticsearch / observability / security.

serverless: ga (and empty serverless:) now applies to all four project types: Elasticsearch, Observability, Security, and Vector Database.

When those four share the same lifecycle, they still collapse to the generic Serverless badge. A page only shows Serverless Vector Database when vectordb is tagged on its own, or when its lifecycle differs from the others.

serverless: ga still means the original three project types. Expanding it to Vector Database would have marked every existing serverless page as applying to a project type that did not exist when those tags were written. Vector Database is opt-in; a page only claims it when tagged explicitly.

Badges follow the same pattern as the other project types, with a longer popover/LLM name because the product is “Elasticsearch Vector Database”: badge Serverless Vector Database, popover Serverless Elasticsearch Vector Database projects.

[theletterf]

OK from my PoV. +CC @shainaraskas @florent-leborgne

[florent-leborgne]

LGTM but just a thought: would vectordb be more syntax friendly (also for authors), and avoid the vector_database/vector-database handling in the code/risks of discrepancies? No strong feeling

[shainaraskas]

what florent said!

[yetanothertw]

LGTM but just a thought: would vectordb be more syntax friendly (also for authors), and avoid the vector_database/vector-database handling in the code/risks of discrepancies? No strong feeling

Very good point, thank you! I've updated the YAML key to: vectordb

[yetanothertw]

serverless: ga still means the original three project types. Expanding it to Vector Database would have marked every existing serverless page as applying to a project type that did not exist when those tags were written. Vector Database is opt-in; a page only claims it when tagged explicitly.

I'm actually not sure about this one at all -- is this the right implementation for this? It kind of seems wrong, when we use serverless: ga is should probably mean all projects types including VectorDB, right? 🤔

[leemthompo]

serverless: ga is should probably mean all projects types including VectorDB, right?

Right. It should. Is there anything idiosyncratic about vectorDB project type that might upset this apple cart?

serverless: ga still means the original three project types. Expanding it to Vector Database would have marked every existing serverless page as applying to a project type that did not exist when those tags were written. Vector Database is opt-in; a page only claims it when tagged explicitly.

This is kinda nonsense. Serverless is versionless so "the past" is meaningless in this context. And all project-types are opt-in 🤔 .

vectordb tags are used to mark information that is specifically applicable to the vector DB project type. ¹.

Footnotes

1. Caveat I'm very hot 🥵 and might be hallucinating ↩

[yetanothertw]

And now I'm stuck and don't know how to fix the failures (Cursor is suggesting I update a hash in a test, but I'm not sure I should be doing that).

@Mpdreamz -- I'll leave this is your capable hands for a review 🥺.
There's no massive rush on this, so can wait until early next week. Thank you in advance