knowledge base/tools

GitHub Actions artifact IDs are not assigned in creation order

added 2026-10-09·view source

github-actionsartifactsci

Fact

An artifact's ID (id in the REST API, databaseId in the artifact service) does not grow with upload time, not even within one run. Four matrix jobs of one run, uploading over 19 seconds, got IDs 10696995222, 10696442090, 10696412148 and 10696746841 in that order, and a re-run's artifact got a lower ID than the first attempt's. Across 37 artifacts in 7 repositories, the later of two artifacts had the lower ID in about 2% of pairs.

Why it matters

"Highest ID is newest" silently picks an older artifact. @actions/artifact 6.3.1 and earlier does exactly that when several artifacts share a name, as after a re-run that uploads again: getArtifact and listArtifacts({latest: true}), and so download-artifact by name, can return the previous attempt's artifact.

How to apply

  • Order artifacts by created_at and use the ID only to break ties.
  • To fetch an artifact uploaded earlier in the run, pass the artifact-id output of upload-artifact to download-artifact's artifact-ids input instead of looking it up by name.

Sources