FastAPI Project Guide

Complete rollout strategy for FastAPI services and async workloads

Use this guide for FastAPI services where async request handling and dependency injection are central.

Architecture Scope

  • API endpoints and dependency graph.
  • Async DB calls and background tasks.
  • Exception handling and response serialization.
  1. Initialize SDK at app startup event.
  2. Instrument middleware for request timing and status.
  3. Wrap outbound calls (DB/HTTP/queue) with spans.
  4. Flush on graceful shutdown event.

Minimum Data Contract

  • service, env, version on all emitted signals.
  • Request ID and user/session context where policy allows.
  • Error type and stack context for triage.

Validation Checklist

  • Synthetic request emits log + span + metric.
  • Error responses include correlated trace context.
  • Shutdown flush emits final queue successfully.

Production Hardening

  1. Restrict sensitive fields before emission.
  2. Tune queue and flush interval for async workloads.
  3. Validate startup/shutdown hooks after framework upgrades.

Troubleshooting

  • Startup works but no data: inspect middleware order.
  • Drops under load: tune queue backpressure settings.
  • Trace gaps: instrument manual spans around async boundaries.

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