API Gateway & Rate Limiting Layer

Repository Shape

Private repositories are represented through architecture notes, impact, and design tradeoffs instead of source links.

Role

Designed the rate-limit algorithm, failure behavior, and tracing signals for a multi-tenant API gateway.

Architecture

• Gateway replicas call a Redis Lua script that refills and consumes tokens in one atomic operation.
• Tenant limits are cached locally and refreshed periodically from PostgreSQL-backed configuration.
• OpenTelemetry spans expose allow/reject decisions, remaining tokens, and Redis latency.

Highlights

• Sub-5ms overhead on the request path.
• Per-tenant controls prevent a single client from degrading shared API capacity.
• Circuit-breaker fallback keeps the platform available during rate-limiter dependency failures.

Constraints