What transport layers does NestJS support for microservices and how do you bootstrap a microservice?

Q: What transport layers does NestJS support for microservices and how do you bootstrap a microservice?

// Standalone microservice — no HTTP server async function bootstrap() { const app = await NestFactory.createMicroservice ( AppModule, { transport: Transport.TCP, options: { host: '0.0.0.0', port: 3001 }, }, ); await app.listen(); } // Hybrid app — HTTP server + microservice listener on the same process async function bootstrap() { const app = await NestFactory.create(AppModule); app.connectMicroservice ({ transport: Transport.RMQ, options: { urls: ['amqp://localhost:5672'], queue: 'orders_queue', }, }); await app.startAllMicroservices(); await app.listen(3000); } TCP — lightweight, direct socket communication; good for internal service-to-service calls. Redis — uses Redis pub/sub; simple to set up; message loss possible if Redis restarts. RabbitMQ (AMQP) — durable queues, exchanges, routing keys; most feature-rich broker. Kafka — high-throughput distributed log; best for event streaming at scale. gRPC — binary protocol over HTTP/2; best for high-performance typed inter-service calls. Transport enum and MicroserviceOptions are exported from @nestjs/microservices.

Difficulty: 5/10

transport layers, microservice bootstrap, NestJS

NestJS supports six built-in transports: TCP, Redis, NATS, MQTT, RabbitMQ (AMQP), Kafka, and gRPC. Bootstrap a standalone microservice with NestFactory.createMicroservice(). For a hybrid app that handles both HTTP and microservice messages in one process, use app.connectMicroservice() after NestFactory.create().

Standalone microservice and hybrid app bootstrap

Transport layer options and bootstrapping rules:

1
TCP — lightweight, direct socket communication; good for internal service-to-service calls.
2
Redis — uses Redis pub/sub; simple to set up; message loss possible if Redis restarts.
3
RabbitMQ (AMQP) — durable queues, exchanges, routing keys; most feature-rich broker.
4
Kafka — high-throughput distributed log; best for event streaming at scale.
5
gRPC — binary protocol over HTTP/2; best for high-performance typed inter-service calls.
6
Transport enum and MicroserviceOptions are exported from @nestjs/microservices.

Scenario Questions

0-2 years experience

2-5 years experience

1Your team wants to switch a NestJS microservice from TCP to NATS for better scalability. Walk me through the changes needed in the bootstrap code and any configuration considerations.

What transport layers does NestJS support for microservices and how do you bootstrap a microservice?

Scenario Questions

Follow-up Questions