System design interview questionMediumObservability
Design a Distributed Logging System
Design a distributed logging system: services emit logs, you ingest at high volume, store cheaply, and allow later search/read.
Interview scope
Producer/Client → Gateway/LB → App → Message Queue; workers → Object Storage (+ optional DB index). No Client → Queue/DB.
Functional requirements
- Accept log events from many producers.
- Buffer/ingest asynchronously.
- Store logs durably and support query/read later.
Scale and quality goals
- Write-heavy, bursty traffic — need a queue/buffer.
- Raw log volume is huge — Object Storage for cheap retention.
- Don’t block app servers on every log fsync in the request path forever.
Capacity assumption
Design for this scale
Assume ~1B log events/day (~12k events/s average); peaks much higher during incidents.
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