Fix Grafana datasource smoke test with Thanos enabled (!523) · Merge requests · Big Bang / Universe / Product / monitoring

Summary

Use the stable Grafana datasource UID (prometheus) instead of its display name. Big Bang names this datasource Thanos when Thanos is enabled. Keep the existing type, health, and live metric assertions unchanged.

Validation

bash tests/grafana-datasource-test.sh: six offline mocked-response regression cases passed, covering both display names and missing datasource, wrong type, unhealthy datasource, and empty metrics. These are not live cluster tests.
helm unittest chart -f 'unittests/*_test.yaml': 50 tests passed.
Chart renders with bbtests and Istio enabled.
README regenerated using Gluon templates and Helm Docs 1.14.2; exact regeneration matches.
Live k3d-dev: Monitoring upgraded through the Big Bang umbrella and Flux from 88.6.2-bb.0 to 91.4.1-bb.1 with Thanos enabled. Both deployed Cypress and script hooks passed, including datasource health and live metric queries. An initial admission-webhook EOF rolled back automatically; the next normal reconciliation succeeded.
Same-cluster supplemental API comparison reproduced the original lookup failure and passed the UID lookup.
Grafana Thanos datasource Save & test succeeded through the standard dev hostname. The existing dev load balancer required temporary HTTPS forwarding to its public ingress; original forwarding and workstation hosts were restored after capture.
All eight CI clean-install and upgrade lanes passed at the final commit. The authservice clean-install retry passed after the first run encountered local-path PVC provisioning timeouts for its Keycloak database and Redis prerequisites.