Limit code guesses

  • Build
  • Lock 06

Difficulty 3 of 5

People sign in with a 6-digit code sent by email: 200 codes/s across 100,000 accounts. A botnet sends 3,000 guesses/s from 5,000 addresses at 10 accounts. Let at most 20 guesses/s through. Fail under 0.5 percent of real codes. Keep p99 under 150 ms.

Play level

HTTP/2HTTP/2SQLUsers3,000 req/sUsers200 req/sLoad balanc…0.5 vCPU · 0.5 GBAPI server0.5 vCPU · 1 GBPostgres1 vCPU · 2 GB
HTTP/2HTTP/2HTTP/2SQLUsers3,000 req/sUsers200 req/sLoad balanc…API serverPostgres
The board at the start of the level
A token bucket on guessesDrag or use arrow keys to change the limit

Limit 1/s per account · all codes tried in 12 days

Goals and limits

Throughput (Guesses)
under 20 req/s
Error rate (Codes)
under 0.5%
p99 latency (Codes)
under 150 ms
Monthly cost
under 40 USD/mo
Parts you can add
Rate limiter, Web firewall, Bot filter, API server
Part limit
4
Traffic
200 req/s

Concepts

How players did

Player results load from the server.

All levels