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VNet peering auto-detects the elb-openapi private IP

Motivation

The Settings → VNet peering "Peer & probe" form hardcoded the OpenAPI private IP default to 10.224.0.7. That address only belongs to an auto-VNet AKS cluster (10.224.0.0/16). For a BYO-subnet cluster — which is the dashboard's own topology (elb-cluster-02 lands inside the platform VNet 10.20.0.0/20, elb-openapi at 10.20.4.15) — the default was always wrong, so the probe timed out and the operator had to look up and type the real IP by hand every time. A stopped cluster's stale IP (10.224.0.7 from the auto-VNet of a Stopped elb-cluster-01) made this especially confusing.

User-facing change

  • The "OpenAPI private IP" field now auto-detects the live elb-openapi internal-LoadBalancer IP for the selected AKS cluster (via GET /api/monitor/aks/service-ip) whenever the cluster selection changes.
  • The field starts empty and is filled in once detection completes; the hint shows the detection state ("Detecting…", "Auto-detected from <cluster>", or a manual-entry fallback when elb-openapi has no LB IP yet).
  • Manual edits are respected — typing an override stops any later auto-detection from clobbering the value.
  • The stale "default 10.224.0.7" copy was removed from the section help text and the VnetPeeringRequest.target_ip doc comment.

API / IaC diff summary

No API or IaC changes. The backend route /api/settings/vnet-peering is unchanged and still accepts an optional target_ip. The UI now always supplies the resolved IP, so the backend's legacy 10.224.0.7 fallback is no longer reached on the UI path (it remains only for direct OpenAPI callers that omit the field, and is correct only for auto-VNet clusters — documented in web/src/api/settings.ts).

Frontend changes only:

  • web/src/components/SettingsPanel.tsx — VnetPeeringSection: empty initial targetIp, a cluster-scoped auto-resolve useEffect, touched-tracking, and updated hint/placeholder/help copy.
  • web/src/api/settings.ts — updated target_ip doc comment.

Validation evidence

  • cd web && npm run build → built in ~7.8s, exit 0.
  • npx eslint src/components/SettingsPanel.tsx src/api/settings.ts → 0 errors (1 pre-existing unrelated exhaustive-deps warning at L2139).
  • Live operational state (production dashboard, prior to this code change) confirmed the root cause and target value: probe http://10.20.4.15/openapi.json → 200 OK · 18.6 ms, both peering directions Connected. This code change removes the manual-typing step that produced that fix.