GitHub metadata syntax

GitHub metadata syntax

The README says that GhaAction comes from GitHub’s metadata syntax page: the inputs and outputs of an action.yml, and the runtime names that runs.using takes.¹

The action module cites sections of the page in see_also: inputs, an input’s deprecationMessage, the outputs of Docker container and JavaScript actions, the outputs of composite actions, and runs for composite, JavaScript and Docker container actions.² The GhaActionRuntime enum holds composite, docker, node20 and node24. Its comment says that SchemaStore’s schema at the pinned commit also accepts node12 and node16, which the page no longer lists.

The page is versionless, so the schema’s version is the date it was read, 2026-10-28. NOTICE says that GitHub’s documentation is licensed under CC BY 4.0, and that the schema renders it in the project’s own words with each page cited by address.

Footnotes

1. README.md, the What it models section and its paragraph on the reading date ↩

2. src/github_actions/schema/github_actions_action.yaml, the see_also entries and the GhaActionRuntime comment ↩