[devantler]

Problem

Coroot's node cost view is wildly inflated for our Hetzner fleet — ~$122/mo per 4 vCPU / 8 GB node and ~$795/mo total, vs. the real Hetzner bill of ~€43 ≈ $50/mo:

	Coroot (before)	Reality
CX33 node (4 vCPU / 8 GB)	~$122/mo	€6.49 ≈ $7.55/mo
Fleet total	$794/mo	~$50/mo

Root cause

Coroot ships embedded pricing only for AWS, GCP and Azure. For nodes on any other cloud it falls back to GCP C4, us-central1 on‑demand rates (db/custom_cloud_pricing.go defaultCustomCloudPricing: per_cpu_core 0.03465, per_memory_gb 0.003938 $/h). That reproduces the screenshot exactly: (4 × 0.03465 + 7.55 × 0.003938) × 730 ≈ $122.9/mo. Idle cost and every per‑app cost allocation inherit the same ~16× inflation.

Fix

A prod-only reconcile CronJob sets the project's Custom Cloud Pricing to Hetzner's CX33 economics — the same source of truth as the existing OpenCost costModel (opencost/helm-release.yaml), so the two cost views agree to the cent:

CX33 = €6.49/mo (4 vCPU / 8 GB) · ECB EUR→USD 1.1637 · 50/50 CPU:RAM split
  per_cpu_core  = €6.49 × 1.1637 × 0.5 / 4 vCPU / 730 = $0.0012933 /vCPU-h
  per_memory_gb = €6.49 × 1.1637 × 0.5 / 8 GB  / 730 = $0.0006466 /GB-h

Coroot prices a node as cpu × per_cpu_core + memGB × per_memory_gb, so a CX33 now reads ~$7.55/mo and the fleet ~$50/mo.

Why a CronJob hitting the API (not the CR or a UI click)

• The coroot-operator's ProjectSpec has no pricing field, and Coroot exposes Custom Cloud Pricing only in the UI — but it's settable via POST /api/project/{id}/custom_cloud_pricing.
• The value persists: Coroot's config/bootstrap.go merges only api keys / notifications / categories onto existing project settings and never touches CustomCloudPricing, so an operator reconcile or pod restart won't reset it.
• authAnonymousRole: Admin (set on the CR) means an in-cluster request that bypasses oauth2-proxy is already Admin → no credential needed.
• A CronJob (not a one-shot Job — same lesson as umami-provision-tenants) makes it a self-healing reconcile loop: sets the price on first install, re-asserts it after a DR restore / PVC wipe that reverts the project to the GCP-C4 default, and corrects UI drift. It's idempotent — a steady-state tick is two GETs and no write.
• Prod-only: the platform project and real cloud spend exist only on Hetzner; the base CR has no projects, so local/CI have only Coroot's auto default project and nothing to correct (same split as the Slack wiring).

Coroot vs. OpenCost (the linked issues)

Coroot's cost model is per-CPU + per-GB only — it cannot do the per-instance Hetzner-API lookup that OpenCost's native hcloud provider (opencost#3710, opencost#3523) can. A blended CX rate is therefore the correct-by-design approach for Coroot. The whole CX line is a fixed 1 vCPU : 2 GB ratio, so this single per-unit rate is exact for our six CX33 control-plane/worker nodes; Hetzner's mild economy-of-scale (CX23 €2.00/vCPU → CX53 €1.41/vCPU) makes it a few % off for other autoscale sizes — still ~16× closer than the GCP fallback, and identical to what OpenCost already reports.

Validation

• kubectl kustomize builds clean for both providers/hetzner/infrastructure (CronJob present) and providers/docker/infrastructure (correctly absent).
• CronJob passes kubectl apply --dry-run=client; the embedded script passes sh -n and its parse / idempotency logic was simulated against realistic /api/user and /custom_cloud_pricing payloads (GCP-fallback → POST, already-correct → SKIP, drift → POST).
• ksail --config ksail.prod.yaml workload validate: 79/80 groups pass. The single failure (providers/hetzner/infrastructure) is the pre-existing stale coroot.com/v1 CRDs-catalog schema rejecting spec.projects[].notificationIntegrations on the already-committed Coroot CR — unrelated to this change (ksail.prod.yaml is protected and lacks the skipKinds:[Coroot] workaround ksail.yaml carries).

Note

No live-cluster steps were run. The price applies on the next CronJob tick (≤30 min) after merge + reconcile; to apply immediately: kubectl create job -n observability --from=cronjob/coroot-custom-cloud-pricing coroot-pricing-now.

🤖 Generated with Claude Code

[botantler-1]

🎉 This PR is included in version 1.34.2 🎉

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