Stop returning alert details in Prometheus Alert Endpoint
Preamble
In !73697 (merged) we added the ability for the Prometheus endpoint (note, docs got removed in !88005 (merged)) to return details for alerts (like IDs and title) for created alerts.
The corresponding issue Return alert id (iid) in POST responses for gen... (#342730 - closed) suggested to return alert IDs for generic HTTP endpoint.
In #342730 (comment 700113244) the scope of the issue was asked
Is this issue just for the generic HTTP endpoint or should we start returning data for Prometheus specific HTTP Endpoint as well?
The proposed solution was scoped for both generic HTTP endpoint and Prometheus endpoint.
We end up returning alert IDs for both endpoints.
Problem
With https://gitlab.com/gitlab-org/gitlab/-/issues/348676 we've started seeing problems for the Prometheus endpoint. One solution (already anticipated in #342730 (comment 700251175)) was to move alert creating into a background job. The fact that the Prometheus endpoint returns IDs and titles of created alerts prevents this approach.
Proposed solution
Stop returning alert IDs in Prometheus Alert Endpoint.
- This endpoint is meant to be used by Prometheus Alertmanager and not by users directly.
- Prometheus Alertmanager does not expect the endpoint to return any content.
- This response body was never documented for Prometheus endpoint - it still is for generic HTTP endpoint.
With this removal we could move alert creation completely into a background job solving https://gitlab.com/gitlab-org/gitlab/-/issues/348676.
Technical details
TBH once approved.