What is NiFi Registry and how does it integrate with NiFi?

NiFi Registry is a complementary subproject that provides centralized storage, management, and versioning of NiFi flow definitions. It functions as a version control system for Process Group configurations — similar in concept to Git for source code.

NiFi Registry organizes flows into Buckets — named containers for flow versions, each with independent access policies. The integration workflow is:

1. Add the Registry URL under NiFi Controller Settings → Registry Clients.

2. Right-click a Process Group on the canvas → Version → Start Version Control, selecting a bucket and flow name. NiFi sends the flow JSON to Registry as version 1.

3. After further changes, commit via Version → Commit Local Changes to create a new snapshot.

4. To promote to production, a production NiFi imports the flow from Registry at the target version — ensuring consistent configuration across environments.

5. To roll back, right-click the versioned group → Version → Change Version to select any previous commit.

Registry exposes a REST API, enabling CI/CD pipelines to promote flow versions from dev to staging to prod without manual canvas operations.