Build: expose env var with the full URL from the current version

[stsewd]

We expose some env vars in our builds https://docs.readthedocs.io/en/stable/builds.html#build-environment, I think it should be useful to add a READTHEDOCS_VERSION_URL or similar. (think we add the full url in the sphinx context, but having an env var would be more general)

Ref #8256 (comment)

[mootari]

This would be really great to have. What open problems / questions are currently blocking this issue?

[humitos]

Hi @mootari! Can you comment here what's the use case you want to handle? I'm curious about how people will use this value.

Also, note there is a current workaround for this that's linked in the description of this issue. That may solve your case for now.

What open problems / questions are currently blocking this issue?

I don't think there is anything blocking this, but it hasn't been a priority for our roadmap and we haven't had the time to implement it.

[mootari]

@humitos The ddev project uses mkdocs in combination with the Material theme. The theme requires a proper site_url in mkdocs.yml, otherwise its error page is completely broken (wrong resource paths, invalid relative navigation links on error pages).

Since mkdocs now supports environment variables in its config, the last missing piece for a straightforward fix of the above problem would be an env var that provides the entire path, since multiple YAML tags / env vars cannot be concatenated.

Related issue: ddev/ddev#2939