Conclusion

The solution of introducing an instanceId configuration was chosen for the following reasons:

1. It is a simple solution that allows to define an instance-id.
2. It does not impact any existing Gerrit functionality, as the instance-id would be null by default.
3. It also creates additional flexibility for multi-master use-cases to populate the instance-id as preferred.
4. It does not impact 3rd party integrations (e.g. CI) because the instance-id won’t be present in the event if not defined.
5. If instance-id is defined but not used by other 3rd party, it can be simply ignored.
6. There might be better fitting alternatives that require much more engineering work in both design and implementation. However, the proposed solution is much simpler and solves a problem immediately (see complexity and impact).
7. The solution was proposed and implementation guaranteed by a long-standing community member (GerritForge) who can be trusted with implementation and benefits from the solution (see community and commitment).

Implementation Plan

Fabio Ponciroli ponch78@gmail.com is driving the implementation, and it will be ready for review in max 2 days. If the timelines of the review process would allow it, it could be included in Gerrit v3.2 or, worst case scenario, in v3.3.