In testing

Yma — E-commerce

Storefront with a resilient backend: circuit breaker, rate limiting and sanitisation

Online store with separate front and backend. The technical interest is in the backend: a Fastify service treated as a system that will fail, rather than one that hopes not to.

Technologies

React
TypeScript
Vite
TanStack Query
Fastify
Prisma
PostgreSQL
Zod
Opossum
Pino
Vitest

Context

A store depends on services it does not own — payment, media, delivery. Each one is a point where the whole store can stop because of somebody else’s outage.

Challenge

External service failure or slowness propagating all the way to the end customer.
User input reaching the database and the HTML untreated.
The need to diagnose production problems without structured logging.

Solution

A circuit breaker per external dependency, its open state cutting the timeout cascade.
Schema validation at the boundary and sanitisation before persistence.
Per-route rate limiting and globally applied security headers.
Structured logging, making request and failure correlatable.

Outcome

Third-party downtime no longer means store downtime.
Backend with automated test coverage.

Highlights

Circuit breaker on outbound calls, isolating third-party failure so it cannot take the store down.
Rate limiting, security headers and HTML sanitisation on input.
Retry with backoff in the HTTP client, so transient network failure never reaches the user as an error.
CPF/CNPJ validation, structured logging and scheduled jobs.
Test suite with coverage on the backend and component tests on the front.