Visitor check-in logger
A small system that records visitors arriving, works hard at recording them leaving, produces a roll call that can be read on a phone in a car park, and collects considerably less personal data than the paper book it replaces. Seven posts on the same system, one diagram at a time, with a cost breakdown and an engineering reference at the end.
- 01
A visitor check-in logger on AWS for a few dollars a month
The whole system on one page — in, out, roll call — and why the check-out problem is the one worth engineering around.
- 02
What the log is actually for
What the roll call has to do, the conditions it operates under, how it is ordered, and why showing doubt is better than showing a clean list.
- 03
How little you need to collect
Which visitor fields have a genuine purpose, why the paper book discloses more than intended, what a photograph creates, and how long to keep anything.
- 04
Why checking out is the hard part
Why check-out fails, the four mechanisms that between them catch most people, why no single one is enough, and how the end of day is handled.
- 05
Contractors are a different problem
Why contractors need a different flow, what a site induction record adds, how deliveries are handled, and the permit-to-work connection.
- 06
What the visitor check-in logger costs
About $4 a month. One Bedrock read per visit is the only line that grows; the queue, the table, the mail and the storage are rounding errors. Plus the three ways the bill could surprise you.
- 07
Engineering reference: the visitor check-in logger architecture
Same system, drawn purely for engineers. Service names, region, Lambda inventory, IAM scopes, the schemas and the exact model id.
Frequently asked questions
- What is a visitor check-in logger?
- A small serverless system that records who has entered a building and, more importantly, who has left, so that an accurate roll call exists during an evacuation.
- Why is checking out harder than checking in?
- Because people are motivated to check in — they want to be let through — and have no reason at all to check out. Most visitor logs are wrong by mid-afternoon.
- What data does it actually need?
- A name, who they are visiting, and a time. Almost everything else that visitor books collect is unnecessary and creates an obligation.
- Should it take photographs?
- Only if there is a specific reason that has been thought about. A photograph of every visitor is a biometric dataset acquired without a purpose.
- What does it cost to run?
- A couple of dollars a month. See part six.