This is a program used to track the attendance in the Innovations Commons at Brophy College Preparatory. It has been used for thousands of sign-ins in dozens of classes, and it is still currently in use.
It has multiple parts:
- an aws lambda and aws dynamodb based backend running in us-west-1 that categorizes and updates the web client in real time
- a rust based cli program running on a raspberry pi connected to a barcode scanner that uploads all student sign-ins to the backend
- a web dashboard that connects to the aws backend via a (still serverless!) websocket, with controlled access to
sign-inshappening on the teacher's account
There are multiple important security and design considerations, especially to make this a solution that could work in multiple classrooms with multiple teachers:
- Teachers must sign in on the barcode scanner, and they can only view
sign-insthat occur while their account is set on the barcode scanner. This prevents a whole host of things, including bad actors remotely tracking students as they go about their days.- in fact, the primary key of a sign in is based on the teachers userid, so they can not even be retrieved by the code without a signed in user.
- Teachers can only sign up to view data if they have a registered Brophy Google email.
- Teachers can claim a room onto their account with a single barcode scan, creating a much easier usecase for teachers without a set room.
- Students just have to scan their barcode to do attendance.
I used this as a testbed for a few different technologies, but the main one was sst. I had never built anything deployed directly onto AWS, so this was a new and exciting experience for me. It also is "local first" in that the web dashboard downloads all signins to indexedb before displaying it.
Here's a diagram explaining how everything works: 