Skip to content
allanninal.dev/build
Collaborate

Part 6 of 7 · Product recall tracer series ~5 min read

What the product recall tracer costs

The model runs on deliveries and on notices, and both are rare. A site taking a hundred delivery lines a week is the driver here; recall notices are a handful a year and cost nothing worth counting. Twelve sites is a small chain. Here is where each cent goes.

Key takeaways

  • About $5 a month at 12 sites. Roughly $14 at 40 sites.
  • One Bedrock read per site is the only line that scales. Everything else is rounding.
  • Nothing is always-on, so a quiet month genuinely costs almost nothing.
  • Nothing in this system runs per sale, so the bill is flat against turnover and rises only with how much stock you take in.
  • The duplicate test runs before the read, so resends are free.
  • The three real risks: a retry loop, storage nobody expires, and a bigger model than the job needs.

The bill at three volumes

These are US East prices at the time of writing, at three volumes that bracket most small businesses. Find the bar closest to your own and read across.

Monthly cost of the product recall tracer at three volumesA stacked bar chart with three bars, one per volume tier: 3 sites totalling about $2, 12 sites totalling about $5, and 40 sites totalling about $14. Each bar is stacked from bands. The largest and fastest-growing is Bedrock, one read per site, in teal. Then SES for the messages, in pink. Then S3 and DynamoDB storage in green. Then a fixed orange band for Secrets Manager and AWS Budgets, which is eighty-six cents at every volume. Then a grey band for Lambda, SQS and CloudWatch. A note says the read is the only bar that grows with the business and the orange band never moves.$0$5$10$15$20~$2.243 sites~$5.0712 sites~$13.8440 sitesBedrock — one read per siteSES — asks, results, receiptsS3 + DynamoDBFixed — Secrets Manager, BudgetsLambda, SQS, CloudWatchThe read is the only bar that grows with the business. The orange fixed band never moves.
Fig 1. The monthly bill at three volumes. The teal band — one model read per site — is the only part that grows; the orange fixed band is the same 86 cents at every volume.

Line by line

LineAt 12 sitesHow it scales
Bedrock read$3.72Linear. One call per site, roughly 1,800 in and 200 out tokens.
SES$0.01Linear. About 2 messages per site.
DynamoDB + S3$0.37Storage grows with what you retain, not with throughput.
Lambda + SQS$0.12Linear, and effectively free at this scale.
CloudWatch$0.16Flat, if you set retention. Unbounded if you do not.
Secrets Manager$0.40Flat. One secret, $0.40 a month.
AWS Budgets$0.46Flat. Two actions, so you find out before the bill does.

Roughly one model call per delivery, against a mid-tier model, because a delivery note is a short document with a small number of fields and a photograph of a case label is mostly optical character recognition. Notices are read with a capable model because there are almost none of them and getting a batch code wrong is the one error the whole system cannot absorb.

The three ways this bill surprises you

Every one of these has happened to somebody, and all three are cheap to prevent.

  • Running a model over the sales export. It is fixed-header CSV and it is the largest file in the system. Parse it; a model here would cost more than every other line combined.
  • Storing every delivery photograph at full resolution forever. Keep the original until the batch balance closes, then keep a downsized copy with the evidence.
  • Re-tracing to answer a follow-up question. Freeze the trace, then query the frozen result. Re-running against live stock a week later gives a different answer and destroys the audit trail.

What it costs when nothing happens

This matters more than the headline number for a seasonal business. In a month with nothing to process the bill is the fixed band: Secrets Manager at forty cents, AWS Budgets at forty-six, and a few cents of storage. Call it a dollar. There is no instance to stop and nothing to remember to turn off.

The monthly bill at four volumes plus one failure modeA horizontal row of five boxes. Quiet month, about one dollar. 3 sites, about $2. 12 sites, about $5. 40 sites, about $14. And one bad retry loop, about two hundred dollars. A note says four of these are the design working and the fifth is a missing dead-letter queue.THE BILL, AT A GLANCEQuiet month~$13 sites~$212 sites~$540 sites~$14One bad loop~$200Four of these are the design working. The fifth is a missing dead-letter queue.
Fig 2. The bill at a glance, including the one that is not a volume at all. A retry loop with no dead-letter queue costs more than every legitimate use of the system put together.
  • Management
  • Analytics
  • Front-end & mobile

Set these on day one

  • A dead-letter queue on every SQS queue, with a maximum receive count of three.
  • Thirty-day retention on every CloudWatch log group. There is no default that is safe.
  • An S3 lifecycle rule on the object prefix, tiering at 90 days and expiring at your actual record-keeping horizon.
  • Two AWS Budgets actions — one that emails at half your expected spend, one at double it. The second is how you find out about a loop in an hour instead of a month.
  • Provisioned concurrency: none. Nothing here is latency-sensitive enough to justify paying for a warm function.

Next: the same system drawn for engineers — service names, resource identifiers, IAM scopes, table schemas and the model id.

All posts