ADR-024 records the deliberate cross-domain link (obs-grafana joins
archiv-net to query archive-db via the SELECT-only grafana_reader role),
the rejected alternatives (Prometheus exporter, read replica, versioned
migration + flyway repair, hardcoded fallback), and the consequences —
specifically that a Grafana compromise gains TCP reach to archive-db
but is bounded by the role's least-privilege grants.
The DEPLOYMENT.md runbook documents the rotation procedure that
R__grafana_reader_password.sql now enables: bump GRAFANA_DB_PASSWORD,
restart backend (Flyway re-applies because the resolved checksum
changed), restart obs-grafana (datasource picks up the new env var).
Also calls out the fail-closed startup behavior so operators who hit
IllegalStateException know it is deliberate.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
