Challenge 12: Capstone: financial aggregator
Banks push 2,100 transaction webhooks a second, and users read dashboards 900 times a second. Banks retry, so 5% of webhooks repeat one already received, and a transaction must never be recorded twice in the relational ledger. Survive the loss of any instance with p99 under 200 ms, for at most 2,100 USD a month.
Traffic demand3,000 RPS30% reads, 70% writes
p99 latency target≤ 200 msSlowest 1% of requests
Availability≥ 99.99%N-1 failure survival (0 drops)
Monthly cloud budget≤ 2,100 USDA month, everything included