Add EC2 Capacity Block pricing

[emilydunenfeld]

https://vantagecommunity.slack.com/archives/C015JVAPSJ3/p1779865489700439

[cristim]

EC2 Capacity Block pricing: feasibility analysis + design proposal

I dug into this against the current scraper/frontend architecture and AWS's data sources. Summary up front: Capacity Block pricing is not cleanly scrapable the way On-Demand / Reserved / Spot / Savings Plans are, because it is dynamic supply-and-demand pricing that AWS does not publish in the Price List Bulk API that this project's pipeline is built on. There is still a viable path (scrape the published "current reservation rate" table) but it comes with real caveats. Details and a concrete design below.

How AWS exposes Capacity Block pricing

Capacity Blocks for ML reserve accelerator capacity (P4d, P4de, P5, P5e, P5en, P6-B200, P6-B300, P6e, Trn1, Trn2) for a fixed future window. Pricing has two parts:

1. A reservation fee (per instance-hour, charged upfront), and
2. An operating-system fee (per instance-hour while instances run; Linux is $0, RHEL/SLES/Ubuntu Pro add a premium).

Per the AWS docs, the reservation fee is dynamic:

"The price of a Capacity Block depends on available supply and demand for Capacity Blocks at the time of purchase ... When you search for a Capacity Block across a range of dates, we return the lowest-priced Capacity Block offering available. After you've reserved a Capacity Block, the price doesn't change."
-- https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/capacity-blocks-pricing-billing.html

The authoritative way to get a real price is the per-account EC2 API DescribeCapacityBlockOfferings (requires InstanceType, InstanceCount, StartDateRange/EndDateRange, CapacityDurationHours), which returns offerings with UpfrontFee for that specific date range and account. This is fundamentally unlike the static, per-region, per-OS offer files the scraper consumes today.

Why the existing pipeline can't capture it directly

The scraper's only pricing source is the AWS Price List Bulk API (pricing.us-east-1.amazonaws.com/offers/v1.0/aws/...), parsed in scraper/aws/awsutils/api_data.go and scraper/aws/ec2/process_data.go for OnDemand / Reserved terms, plus Savings Plans index files (get_savings_plans.go) and a few HTML/JSON website scrapes (T2 credits, dedicated-host calculator JSON). Capacity Block reservation fees are not published as a term in those offer files - they only exist behind DescribeCapacityBlockOfferings, which is date-range and account scoped and returns market prices. So there is no static term to map into a new EC2PricingData field the way Reserved or Spot is.

The one scrapable source, and its caveats

AWS does publish a human-readable "current reservation rates" table on the pricing marketing page: https://aws.amazon.com/ec2/capacityblocks/pricing/ . It lists per-instance-hour reservation fees split by US / non-US region, plus the per-OS fees. Sample (US regions, captured June 2026):

Instance	Reservation fee (US) /inst-hr	Reservation fee (non-US)
p4d.24xlarge	$11.80	$11.80
p5.48xlarge	$34.608	$31.464
p5e.48xlarge	$39.799	$39.799
p5en.48xlarge	$45.768	$41.612
p6-b200.48xlarge	$82.368	$98.8416
trn1.32xlarge	$9.532	$9.532
trn2.48xlarge	$35.7608	(US only)

OS fees (per instance-hour, on top): Linux $0.000, RHEL $1.8432 (large) / $1.0368 (medium), RHEL-HA $3.8592 / $2.3808, SLES $0.125, Ubuntu Pro $0.336 / $0.168.

Caveats that make this only a partial solution:

• It is a representative / "current" rate, not the price you'll actually pay. The real price floats with supply/demand and is only knowable per date-range via the API. AWS revises this table periodically (the table itself notes the next scheduled update).
• It is an unstructured marketing HTML page with no documented stable JSON endpoint (unlike the dedicated-host calculator JSON the scraper already uses). The only machine-readable copy I found is a community scrape (https://github.com/koyakimu/ec2-capacity-blocks-for-ml-pricing-json), i.e. someone else screen-scraping the same page. A scraper built on this will break whenever AWS restyles the page.
• Coverage is US/non-US buckets, not the per-region granularity the rest of the site uses, and only ~10 GPU/accelerator families.

Recommended path

Do not wire Capacity Blocks into the normal pricing pipeline as if it were another static term (it would silently present a market price as if it were fixed, violating the project's "fail loud, no magic values" stance). Instead, if the feature is wanted, implement it explicitly as a clearly-labelled "representative starting price" with a disclaimer. Two concrete options, in order of preference:

Option A - scrape the published rate table (medium effort, fragile):

• Scraper: new scraper/aws/ec2/capacity_block_pricing.go, modeled on t2.go / dedicated_host_pricing.go (use awsutils.FetchDataFromAWSWebsite or soup HTML parsing). Fetch the reservation-fee table + OS-fee table from the pricing page, map US -> US regions and non-US -> the rest. Fail loud if the table layout no longer parses (so a silent break is caught), rather than emitting stale/empty data.
• Data: add CapacityBlock *Price (reservation fee, per instance-hour) to EC2PricingData in ec2_instance.go, populated only for eligible families; nil/omitted for everything else. Optionally add the OS-fee delta, but Linux is the common case ($0) so the reservation fee alone is the useful signal.
• Frontend: add capacity_block?: string to PlatformPricing in next/types.ts, a (pricing) => pricing?.linux?.capacity_block column in next/utils/colunnData/ec2/columns.tsx mirroring the Spot columns, gated so it only shows for GPU/accelerator families, with a tooltip/disclaimer: "Representative Capacity Block reservation rate; actual price is dynamic - confirm via DescribeCapacityBlockOfferings."
• Test: regression test in the scraper parsing a saved copy of the table HTML into the expected fields (fails before the parser exists, passes after).

Option B - link out (low effort, honest): add a small "Capacity Block" indicator/column for eligible families that links to the AWS pricing page and the DescribeCapacityBlockOfferings docs, with no scraped number. Avoids presenting a price that may be wrong by the time a user reads it.

My recommendation: Option A with a prominent "representative / dynamic" disclaimer, only if maintainers are comfortable with a marketing-page HTML scraper that will need occasional repair. If not, Option B is the safe, honest choice. I deliberately did not open a code PR, because forcing the dynamic reservation fee into the static per-region/per-OS pricing model would present a market-rate estimate as a fixed price, which I don't think matches the bar for this codebase. Happy to implement either option if a maintainer picks one.

Sources:

• https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/capacity-blocks-pricing-billing.html
• https://aws.amazon.com/ec2/capacityblocks/pricing/
• https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-capacity-blocks.html
• DescribeCapacityBlockOfferings: https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DescribeCapacityBlockOfferings.html

[cristim]

@Bensign @emilydunenfeld what's your take on this?