Problems / Design a product, medium
Design a log pipeline from an empty canvas: agents on every server ship batches, every line is indexed for search within seconds, and nothing is ever lost.
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Request types to route: ship (90%, write), search (10%, read). Budget: $6,500 a month.
You start from an empty canvas. When you run the tests, each one simulates your design with its own traffic and failures:
| Test | What it does | Passes when |
|---|---|---|
| Normal day | The normal day: the traffic in the brief, nothing broken. | Success ≥ 99.9%; p99 latency ≤ 150 ms (ship); p99 latency ≤ 500 ms (search); No lost events |
| An incident: debug logging everywhere | At 5 s an incident starts and every service logs at debug level: traffic triples for 8 s. | Success ≥ 99%; p99 latency ≤ 300 ms (ship) |
| The log stream goes down | At 5 s the log stream (the Kafka cluster) crashes and takes 10 s to come back, while every agent keeps shipping. | Success ≥ 99%; No lost events |
| A server dies | At 4 s one server of the first app service on the request path dies for 10 s. | Success ≥ 99% |
| Budget: $6,500/month | The normal day's design must cost at most $6,500 a month. | Cost ≤ $6,500/month |