Fan-In - CI/CD Glossary Definition
Fan-in collects the outputs of many parallel jobs into one aggregation job.
Fan-in is the point where many parallel CI jobs converge into a single downstream job that aggregates their results, such as merging coverage or publishing a combined report.
Fan-in is the counterpart to fan-out. After work is spread across parallel jobs, a single job waits on all of them (via needs) and combines the outputs.
How it works
The aggregation job lists every parallel job in needs: so it starts only after they all finish, then downloads their artifacts and merges them.
In CI
A failed fan-in job often means one upstream shard failed or an artifact was missing. Check that every parallel job uploaded its expected artifact name.