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Logging System Design
Visual Problem Diagram
Scenario
It is 2am during an incident. Services produce hundreds of terabytes of logs per day, one bad deployment turns on noisy debug lines, and on-call needs to tail fresh logs and search the last few days without a rogue query killing the search cluster. The system must ingest reliably, protect applications from logging backpressure, redact sensitive data, and keep cost under control.
Design a centralized logging system that collects application logs, stores them durably enough for their class, supports search and alerting, and keeps ingestion, query latency, and retention cost under control.
Constraints
Collect logs from services, parse structured fields, redact sensitive data, index recent data, search with filters, support dashboards and alerts, retain old data by policy.
High ingest availability, bounded query latency for recent data, controlled storage cost, tenant isolation, clear loss policy, and no sensitive data leaking through logs.
Millions of events per second, hundreds of terabytes per day, thousands of services, hot search for recent days, cold retention for months or years.
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