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Fastify in Moost

In this guide, we will explain how you can integrate an existing Fastify application with Moost. While Moost already comes with the capability to create a standalone HTTP server through the @wooksjs/event-http package, you may have an existing Fastify app you wish to use without rewriting the entire application. Thankfully, Moost provides a way to achieve this.


Before proceeding, ensure you have the following dependencies installed:

  • fastify
  • moost
  • @moostjs/event-http
  • @wooksjs/fastify-adapter


Here's an example of how to integrate Fastify with Moost:

import { MoostHttp, Get } from '@moostjs/event-http'
import { Moost, Param } from 'moost'
import { WooksFastify } from '@wooksjs/fastify-adapter'
import fastify from 'fastify'

class MyServer extends Moost {
    hello(@Param('name') name: string) {
        return `Hello, ${name}!`

const fastifyApp = fastify()
const moostApp = new MyServer()
const httpAdapter = new MoostHttp(new WooksFastify(fastifyApp))
httpAdapter.listen(3000, () => {
    moostApp.getLogger('my-app').info('Up on port 3000')

In this example, we start by importing the necessary packages and defining a Moost server with a single endpoint at hello/:name.

We then create a Fastify app and a Moost app instance. Next, we create an HTTP adapter for our Moost app, passing a new instance of WooksFastify initialized with our Fastify app to the MoostHttp constructor.

We add the adapter to the Moost app, initialize the Moost app, and then start listening on port 3000 with our Fastify app. All HTTP requests are now managed by Moost, with the underlying Fastify app handling the actual server.


As you can see, Moost provides a simple way to integrate with Fastify. This allows you to leverage the power and flexibility of Moost while utilizing Fastify's fast and low overhead HTTP server capabilities.

This integration makes it possible to transition gradually to a Moost architecture, or to keep using Fastify as your HTTP server while taking advantage of Moost's features for your application logic.

Released under the MIT License.