Bug: alertmanager: too many 404 errors with S3 backend to /mimir-alertmanager/grafana_alertmanager/org/grafana_fullstate

[pschiffe]

What is the bug?

Even with grafana_alertmanager_compatibility_enabled: false my S3 backend (minio) is receiving a lot of requests for file /mimir-alertmanager/grafana_alertmanager/org/grafana_fullstate, but that path doesn't exist. The correct path is /mimir-alertmanager/alertmanager/org/fullstate. This is then generating lot of 404 errors. Otherwise the alertmanager seems to be working fine.

When I enable grafana_alertmanager_compatibility_enabled: true, the number of 404 errors is roughly doubled.

How to reproduce it?

Enable alertmanager with S3 backend.

What did you think would happen?

No 404 errors.

What was your environment?

Mimir 2.15.0 cluster running in Docker on 3 hosts.

Any additional context to share?

No response