Add ROSA migration/import calculator for VMware and existing cluster inventory

[paulczar]

Summary

Add a separate standalone calculator for importing existing VMware / OpenShift / cluster inventory and proposing ROSA HCP worker mixes with cost estimates.

This is distinct from the ROSA HCP Cost Calculator, which prices a known ROSA shape (instance type + count). The import tool would answer: “I have existing capacity; what ROSA HCP options should I consider?”

Inspired by the multi-cluster inventory import on Will Garcia’s ROSA Calculator.

Problem

Customers migrating from VMware or existing clusters usually have per-VM / per-worker capacity and utilization data, not a finished ROSA machine-pool design. Today they either:

• Manually invent instance types/counts in the HCP Cost Calculator / Fleet Optimizer, or
• Use an external tool for rightsizing, then re-enter results

We want a first-class experts-site tool that ingests inventory, proposes scenarios, and hands off a chosen mix into our existing calculators.

Proposed approach

New standalone app under the existing docs pattern (assets/ + custom layout + /experts/...), not a mode inside the HCP Cost Calculator.

Inputs (v1)

• .xlsx (preferred) and/or CSV compatible with Will Garcia’s multi-cluster format:
  • One sheet/tab per cluster
  • Columns: vCPU (Count), vCPU Usage (%), Memory Size (GiB), Memory Usage (%), Provisioned Storage (GB), Storage Usage (%)
• Target AWS region
• Guidance: worker / VM data only (exclude control-plane / infra that ROSA manages)

Core behavior

1. Summarize inventory (spec totals vs used capacity from utilization)
2. Generate ROSA HCP scenario options per cluster (start smaller than Will’s full matrix), for example:
   • Closest like-for-like (amd64)
   • Binpack to used CPU/memory (amd64)
   • Optional: Graviton variant
3. Price each scenario using shared HCP building blocks:
   • EC2 from region pricing snapshots
   • ROSA worker node fee (PAYGO / private offer tiers)
   • HCP cluster fee ($0.25/hr)
   • Optional EBS (call out explicitly; HCP calculator currently excludes it)
4. Let the user pick a scenario and hand off to:
   • HCP Cost Calculator (instance pools + cluster count), and/or
   • Fleet Optimizer (aggregated vCPU / contract tier)

Non-goals (v1)

• Full Will Garcia scenario matrix (all burstable/metal/virt variants)
• Classic ROSA control-plane / infra EC2 modeling
• Live cloud API discovery (RVTools/CSV upload is enough for v1)

Relationship to existing tools

Tool	Job
HCP Cost Calculator	Price a known ROSA HCP design
Fleet Optimizer	Fleet-level contract / optimization modeling
Import / migration calculator (this issue)	Inventory → proposed ROSA mixes → cost compare → handoff

Share pricing data refresh / snapshot conventions where practical (static/rosa/... feeds, refresh script patterns).

Acceptance criteria

• Standalone page published under /experts/rosa/... with site chrome (header/nav/footer/consent)
• Upload Will-compatible multi-cluster .xlsx (one tab per cluster)
• Show at least two priced scenarios per cluster (like-for-like + binpack)
• Clear disclaimer that results are estimates, not quotes
• Handoff path into HCP Cost Calculator and/or Fleet Optimizer
• Unit tests for parse + rightsizing helpers
• Brief maintainer note for template format and data assumptions

References

• Will Garcia calculator: https://rosa.wigarcia.com/ (Multi cluster Inventory Import)
• Template (Google Sheet): https://docs.google.com/spreadsheets/d/1p9duRgZlhNZhtaykEILvlsR7L7RecyHm/edit?usp=sharing
• Related PR: Add ROSA HCP Cost Calculator with multi-region pricing and shareable scenarios #970
• Design pattern: standalone apps in AGENTS.md (assets/ + layout placeholders)

Suggested next step

Write a short design spec under docs/superpowers/specs/ before implementation (scope scenarios, handoff payload, EBS policy, and whether to vendor SheetJS or require a CSV pre-convert).