@nestarc/feature-flag

DB-backed feature flags for NestJS + Prisma + PostgreSQL -- tenant-aware overrides, percentage rollouts, and zero external dependencies.

Features

• Database-backed -- flags stored in PostgreSQL via Prisma, no external service required
• Tenant / user / environment overrides -- granular control per tenant, user, or deployment environment
• Percentage rollouts -- deterministic hashing (murmurhash3) for consistent per-user bucketing
• Guard decorator -- @FeatureFlag() automatically gates routes and controllers
• Bypass decorator -- @BypassFeatureFlag() exempts health checks and public endpoints
• Programmatic evaluation -- isEnabled() and evaluateAll() for service-layer logic
• Built-in caching -- configurable TTL with manual invalidation
• Event system -- optional integration with @nestjs/event-emitter for audit and observability
• Testing utilities -- drop-in TestFeatureFlagModule for unit and integration tests

Installation

npm install @nestarc/feature-flag

Peer dependencies

npm install @nestjs/common @nestjs/core @prisma/client rxjs reflect-metadata

Optional

# Required only if you enable emitEvents
npm install @nestjs/event-emitter