CostLensRDS Reserved Instance Opportunity

RDS Reserved Instance Opportunity

CostLens surfaces AWS Cost Explorer Reserved Instance purchase recommendations for steady-state RDS databases, with break-even and estimated savings.

Updated June 20261 min read

RDS Reserved Instances cost up to ~69% less than on-demand for the same database. For predictable, always-on databases that's pure savings. CostLens reads AWS's own Cost Explorer recommendation and presents it as an actionable, sized purchase option.

How it works

CostLens queries Cost Explorer

Calls ce:GetReservationPurchaseRecommendation for Amazon RDS (runs once — Cost Explorer is global).

Parses each recommendation

Extracts instance family, term, payment option, recommended quantity, estimated monthly savings, and break-even months.

Filters to meaningful spend

Only surfaces recommendations where covered on-demand spend exceeds $100/month.

What to do

  1. Open the recommendation — the detail view shows term, payment option, break-even months, and annual savings.
  2. Confirm the database is genuinely steady-state (RIs are a 1- or 3-year commitment).
  3. Purchase the Reserved Instance in the AWS console. This check is advisory — it informs the decision rather than buying automatically.

Sized from your real usage

The recommendation comes from AWS Cost Explorer, sized on your actual RDS usage over the lookback window — not a generic estimate.

Required IAM permissions

Read-only — covered by the CostLens ReadOnlyAccess policy from AWS Accounts:

ce:GetReservationPurchaseRecommendation

Limitations

  • Advisory only — RI purchases are customer-initiated in the AWS console.
  • Defaults to a 1-year, No Upfront recommendation; other terms/payment options can be compared in the AWS console.
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