Cache Service

Repo: o-apps/cache-service (fluxcd app directory: cache-api) · Port: 8080 (HTTP), 9090 (gRPC)

A thin wrapper around Redis, exposed over both HTTP and gRPC, so no other service needs a direct Redis client dependency. If Redis is unavailable or unconfigured, it transparently falls back to an in-memory backend — useful for local dev, but rate limits and cached values then don't survive a restart or apply across replicas.

Why This Exists

Several services (auth-service for login rate limiting, others for general caching) need a shared cache without each one importing and configuring a Redis client directly. cache-service centralizes that: the backend (Redis vs. in-memory) is chosen once, here, behind a ports.CacheRepository interface — consumers only ever see a small HTTP/gRPC API.

Key Capabilities

• Basic cache operations — get/set/delete by key, with TTL
• Atomic increment-with-expiry — IncrementWithExpiry is a sliding-window counter (each call resets the TTL), the primitive auth-service's login/register rate limiter is built on
• Dual interface — the same operations are available over HTTP (for services that don't want a gRPC client) and gRPC (lower overhead for high-frequency callers)

Auth

All /cache/* routes require an X-Api-Key matching the shared API_KEY secret; /health is public. Introduced after an audit found cache-service's counters (including rate-limit state) were resettable by anyone with network access.

REST API

Method	Path	Description
GET	/cache/{key}	Get a value
POST	/cache	Set a value (body includes key, value, TTL)
DELETE	/cache/{key}	Delete a value
POST	/cache/{key}/increment	Atomic increment with TTL reset (sliding window)
GET	/health	Health check (unauthenticated)

Environment Variables

Variable	Description
REDIS_ADDR	Redis address, e.g. redis:6379; falls back to in-memory if unreachable
REDIS_PASS	Redis password (optional)
REDIS_DB	Redis logical DB number (default: 0)
API_KEY	Shared secret the X-Api-Key middleware validates against
HTTP_PORT / GRPC_PORT	HTTP and gRPC ports (defaults: 8080 / 9090)