Exercise 1: Implement Redis Outage Circuit Breaker

[harsharajkumar-273]

Goal

Enhance the resilience of the API Ingestion Gateway by implementing a fallback mechanism.

Problem

Currently, if Redis crashes or loses network connectivity, redis.get() in src/middleware/auth.ts throws an unhandled error, resulting in an HTTP 500 status and halting all metric ingestions.

Task

1. Wrap Redis cache lookup and sets in src/middleware/auth.ts inside a try/catch block.
2. On connection error, log the failure as a warning and query PostgreSQL directly to validate the API key.
3. Design a simple in-memory LRU or Map cache to store key validations locally for 30 seconds to prevent DB connection pool exhaustion during a Redis outage.