Create an extension that reads common used attributes from a central file

[mmattel]

When we once upgrade to Antora 3

...Reading this correcly, using such an extension in an multi-repo environment, I could make a "central" accessible file (like via rawgithubusercontent) defining common used attributes that can be automatically included without redefining them in each repo again and again?...

Answer - yes

Get asciidoc attributes values from external sources

References #4853

[DeepDiver1975]

🤖 Automated issue triage by Claude Code review agent.

This request — an Antora extension that reads commonly-used attributes from a central file so they don't have to be redefined in each repo — has been implemented. Closing as resolved.

The extension ext-antora/load-global-site-attributes.js (currently v1.0.0) does exactly this: it loads global AsciiDoc attributes into the playbook (site.yml) from a configurable attributefile. That file can be either a local path or an http(s):// URL (e.g. a raw.githubusercontent.com resource), which directly supports the central / multi-repo use case described here. The shared attributes themselves live in global-attributes.yml. Playbook attributes take precedence over the loaded ones, so a repo can still override values locally.

This is the same "central global attributes" work tracked by the previously-closed #3817 and #4705. If something about the current implementation still falls short of what you need here, please reopen with the specific gap — thanks!