Scalable microservices platform built with NestJS, TypeScript, PostgreSQL/Prisma, RabbitMQ, and Docker

npm i
cp .env.example .env
docker-compose up --build -d

flowchart LR
    subgraph apps [Microservices]
        gateway[(API Gateway)]
        user_svc[(User Service)]
        notif_svc[(Notification Service)]
    end
    subgraph infrastructure [Infrastructure]
        postgres[(PostgreSQL)]
        rabbitmq[(RabbitMQ)]
    end
    subgraph external [External Services]
        webhook[(Webhook API)]
    end
    client((Client)) -->|HTTP| gateway
    gateway -->|RPC| user_svc
    user_svc -->|Event| rabbitmq
    rabbitmq -->|Deferred Queue| notif_svc
    user_svc <-->|SQL| postgres
    notif_svc -->|HTTP| webhook

• api-gateway - REST API entry point built with Fastify. Handles HTTP requests and forwards them to appropriate microservices via RabbitMQ RPC.

• user-service - Manages user CRUD operations with Prisma ORM. Emits events for user lifecycle actions (creation, updates, deletion).

• notification-service - Consumes deferred notification events from RabbitMQ and sends them to external webhook API. Uses Dead Letter Exchange (DLX) pattern for scheduled delivery.

• shared - Contains shared DTOs, constants, configuration, and utilities used across all microservices.

• Microservices architecture - Each service is independently deployable and scalable. Services communicate via RabbitMQ for loose coupling.

• Deferred notifications - RabbitMQ DLX pattern enables scheduled message delivery without external cron jobs or schedulers.

• Pino logger - Structured JSON logging for production with pretty-printing for local development.

• Prisma ORM - Type-safe database access with automatic migrations and client generation.

• Code quality - ESLint + Prettier configured for consistent code style with VS Code integration.

• Docker 28.5+ (+ docker-compose)
• Node.js 24+ (LTS recommended)
• npm 11.6+

1. Install dependencies:

   npm install

2. Environment - Copy .env.example → .env and configure:

   cp .env.example .env

   Key variables:

   • DATABASE_URL - PostgreSQL connection string
   • RABBITMQ_URL - RabbitMQ connection string
   • NOTIFICATION_WEBHOOK_URL - External webhook endpoint
   • NOTIFICATION_DELAY_MS - Notification delay in milliseconds (default: 5000)

3. Start services - Launch all microservices with Docker:

   docker-compose up --build -d

4. Run migrations - Apply Prisma schema to database:

   docker-compose exec api-gateway npx prisma migrate deploy

5. Browse API - Open http://localhost:3000/api to access the API Gateway.

1. User Created - When a user is created via API Gateway, user-service emits an event.
2. Deferred Queue - Event is published to deferred_queue with TTL (configurable via NOTIFICATION_DELAY_MS).
3. Dead Letter Exchange - After TTL expires, message is moved to notification_queue.
4. Notification Service - Consumes message and sends HTTP POST to external webhook.

This pattern allows for scheduled notifications without polling or external schedulers.

• NestJS 11.1.8 - Progressive Node.js framework
• TypeScript 5.9.3 - Type-safe JavaScript
• Fastify - High-performance web framework
• Prisma 6.19.0 - Next-generation ORM
• RabbitMQ - Message broker with DLX support
• PostgreSQL - Relational database
• Pino - Fast JSON logger
• Docker - Containerization

MIT