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Design a metrics collection and alerting system

SnapchatSoftware Engineer · Onsite
MediumSoftware EngineerOnsiteSystem Design

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This question evaluates system design competencies such as scalable time-series data modeling, ingestion and storage architecture, query latency versus retention trade-offs, and alert evaluation logic within the System Design domain.

Design a metrics collection and alerting system (like a simplified monitoring platform).

Functional requirements:

  • Collect time-series metrics from many services/hosts (e.g., counters, gauges, timers).
  • Support near real-time querying/dashboards (low-latency queries over recent data).
  • Support offline/analytical queries over long time ranges (heavier aggregations, historical analysis).
  • Support alerting: user-defined rules (e.g., threshold, rate of change) with notifications.

Non-functional requirements:

  • High write throughput, horizontal scalability, high availability.
  • Handle spikes, backpressure, and partial failures.
  • Reasonable multi-tenancy and access control.

Provide an end-to-end architecture, key data models, storage choices, and how alert evaluation works. Discuss tradeoffs (e.g., Lambda/Kappa style), retention, and handling high-cardinality metrics.