Documentation

Factory

The Fastify module exports a factory function that is used to create new Fastify server instances. This factory function accepts an options object which is used to customize the resulting instance. This document describes the properties available in that options object.

http2 (Status: experimental)

If true Node.js core's HTTP/2 module is used for binding the socket.

• Default: false

https

An object used to configure the server's listening socket for TLS. The options are the same as the Node.js core createServer method. When this property is null, the socket will not be configured for TLS.

This option also applies when the http2 option is set.

• Default: null

ignoreTrailingSlash

Fastify uses find-my-way to handle routing. This option may be set to true to ignore trailing slashes in routes. This option applies to all route registrations for the resulting server instance.

• Default: false

const fastify = require('fastify')({
  ignoreTrailingSlash: true
})

// registers both "/foo" and "/foo/"
fastify.get('/foo/', function (req, reply) {
  res.send('foo')
})

// registers both "/bar" and "/bar/"
fastify.get('/bar', function (req, reply) {
  res.send('bar')
})

maxParamLength

You can set a custom length for parameters in parametric (standard, regex and multi) routes by using maxParamLength option, the default value is 100 characters.
This can be useful especially if you have some regex based route, protecting you against DoS attacks.
If the maximum length limit is reached, the not found route will be invoked.

bodyLimit

Defines the maximum payload, in bytes, the server is allowed to accept.

• Default: 1048576 (1MiB)

logger

Fastify includes built-in logging via the Pino logger. This property is used to configure the internal logger instance.

The possible values this property may have are:

• Default: false. The logger is disabled. All logging methods will point to a null logger abstract-logging instance.

• pinoInstance: a previously instantiated instance of Pino. The internal logger will point to this instance.

• object: a standard Pino options object. This will be passed directly to the Pino constructor. If the following properties are not present on the object, they will be added accordingly:

  • genReqId: a synchronous function that will be used to generate identifiers for incoming requests. The default function generates sequential identifiers.
  • level: the minimum logging level. If not set, it will be set to 'info'.
  • serializers: a hash of serialization functions. By default, serializers are added for req (incoming request objects), res (outgoing repsonse objets), and err (standard Error objects). When a log method receives an object with any of these properties then the respective serializer will be used for that property. For example:

      fastify.get('/foo', function (req, res) {
        req.log.info({req}) // log the serialized request object
        res.send('foo')
      })
    

    Any user supplied serializer will override the default serializer of the corresponding property.

serverFactory

You can pass a custom http server to Fastify by using the serverFactory option.
serverFactory is a function that takes an handler parameter, which takes the request and response objects as parameters, and an options object, which is the same you have passed to Fastify.

const serverFactory = (handler, opts) => {
  const server = http.createServer((req, res) => {
    handler(req, res)
  })

  return server
}

const fastify = Fastify({ serverFactory })

fastify.get('/', (req, reply) => {
  reply.send({ hello: 'world' })
})

fastify.listen(3000)

Internally Fastify uses the API of Node core http server, so if you are using a custom server you must be sure to have the same API exposed. If not, you can enhance the server instance inside the serverFactory function before the return statement.

caseSensitive

By default, value equal to true, routes are registered as case sensitive. That is, /foo is not equivalent to /Foo. When set to false, routes are registered in a fashion such that /foo is equivalent to /Foo which is equivalent to /FOO.

Setting caseSensitive to false will also result in all params (and all value matched by regexps) to be lowercased as well.

fastify.get('/user/:username', (request, reply) => {
  // Given the URL: /user/NodeJS
  console.log(request.params.username) // -> 'nodejs'
})

Please note this setting this option to false goes against RFC3986.

requestIdHeader

The header name used to know the request id. See the request id section.

• Default: 'request-id'