Performance (Fastify)

Under the hood, Nest makes use of Express, but as mentioned already, provides compatibility with a wide range of other libraries, like e.g. Fastify. How does it work? In fact, what Nest needs to use your favorite library, is a compatible adapter, that primarily proxies corresponding handlers to appropriate library-specific methods. Additionally, your library has to provide at least similar request-response cycle management as express.

A Fastify fits here very well because it solves design issues in a similar manner as express does. However, fastify is much faster, achieving almost two times better benchmarks results. The question, why Nest still uses express as a default HTTP provider then? Because express is widely-used, well-known, and has a huge set of compatible middleware.

But we don't lock people in a single paradigm. We let them use whatever they need. Fastify is a better choice when you care about really good performance, that's why we provide a built-in FastifyAdapter that helps to integrate this library with Nest.

Installation

Firstly, we need to install required packages:


$ npm i --save fastify fastify-formbody

Adapter

Once fastify is installed, we can use a FastifyAdapter.

TypeScript


import { NestFactory, FastifyAdapter } from '@nestjs/core';
import { ApplicationModule } from './app.module';

async function bootstrap() {
  const app = await NestFactory.create(ApplicationModule, new FastifyAdapter());
  await app.listen(3000);
}
bootstrap();

If you're running your Nest instance inside of a docker container you will need to specify the host, like so:

TypeScript


await app.listen(3000, '0.0.0.0');

And that's all. Also, you are able to pass options into fastify constructor through FastifyAdapter constructor. Keep in mind that now, Nest uses fastify as an HTTP provider, meaning, each recipe that relays on express won't work anymore. You should rather use fastify equivalent packages.

A working example is available here.