@fastify/basic-auth

A simple Basic auth plugin for Fastify.

Install

npm i @fastify/basic-auth

Compatibility

Plugin version	Fastify version
^6.x	^5.x
^4.x	^4.x
^1.x	^3.x
^0.x	^2.x
^0.x	^1.x

Please note that if a Fastify version is out of support, then so are the corresponding versions of this plugin in the table above. See Fastify's LTS policy for more details.

Usage

This plugin decorates the fastify instance with a basicAuth function, which can be used inside any hook before a route handler, or with @fastify/auth.

const fastify = require('fastify')()
const authenticate = {realm: 'Westeros'}
fastify.register(require('@fastify/basic-auth'), { validate, authenticate })
// `this` inside validate is `fastify`
function validate (username, password, req, reply, done) {
  if (username === 'Tyrion' && password === 'wine') {
    done()
  } else {
    done(new Error('Winter is coming'))
  }
}

fastify.after(() => {
  fastify.addHook('onRequest', fastify.basicAuth)

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

Promises and async/await are supported as well!

const fastify = require('fastify')()
const authenticate = {realm: 'Westeros'}
fastify.register(require('@fastify/basic-auth'), { validate, authenticate })
async function validate (username, password, req, reply) {
  if (username !== 'Tyrion' || password !== 'wine') {
    return new Error('Winter is coming')
  }
}

Use with onRequest:

const fastify = require('fastify')()
const authenticate = {realm: 'Westeros'}
fastify.register(require('@fastify/basic-auth'), { validate, authenticate })
async function validate (username, password, req, reply) {
  if (username !== 'Tyrion' || password !== 'wine') {
    return new Error('Winter is coming')
  }
}

fastify.after(() => {
  fastify.route({
    method: 'GET',
    url: '/',
    onRequest: fastify.basicAuth,
    handler: async (req, reply) => {
      return { hello: 'world' }
    }
  })
})

Use with @fastify/auth:

const fastify = require('fastify')()
const authenticate = {realm: 'Westeros'}
fastify.register(require('@fastify/auth'))
fastify.register(require('@fastify/basic-auth'), { validate, authenticate })
async function validate (username, password, req, reply) {
  if (username !== 'Tyrion' || password !== 'wine') {
    return new Error('Winter is coming')
  }
}

fastify.after(() => {
  // use preHandler to authenticate all the routes
  fastify.addHook('preHandler', fastify.auth([fastify.basicAuth]))

  fastify.route({
    method: 'GET',
    url: '/',
    // use onRequest to authenticate just this one
    onRequest: fastify.auth([fastify.basicAuth]),
    handler: async (req, reply) => {
      return { hello: 'world' }
    }
  })
})

Custom error handler

On failed authentication, @fastify/basic-auth calls the Fastify generic error handler with an error and sets err.statusCode to 401.

To properly 401 errors:

fastify.setErrorHandler(function (err, req, reply) {
  if (err.statusCode === 401) {
    // This was unauthorized! Display the correct page/message
    reply.code(401).send({ was: 'unauthorized' })
    return
  }
  reply.send(err)
})

Options

utf8 (optional, default: true)

User-ids or passwords with non-US-ASCII characters may cause issues unless both parties agree on the encoding scheme. Setting utf8 to true sends the 'charset' parameter to prefer "UTF-8", increasing the likelihood that clients will use that encoding.

strictCredentials (optional, default: true)

Setting strictCredentials to false allows additional whitespaces at the beginning, middle, and end of the authorization header. This is a fallback option to ensure the same behavior as @fastify/basic-auth version <=5.x.

validate (required)

The validate function is called on each request made and is passed the username, password, req, and reply parameters, in that order. An optional fifth parameter, done, can be used to signify a valid request when called with no arguments or an invalid request when called with an Error object. Alternatively, the validate function can return a promise, resolving for valid requests and rejecting for invalid. This can also be achieved using an async/await function, and throwing for invalid requests.

See code above for examples.

authenticate <Boolean|Object> (optional, default: false)

The authenticate option adds the WWW-Authenticate header and can set the realm value.

This can trigger client-side authentication interfaces, such as the browser authentication dialog.

Setting authenticate to true adds the header WWW-Authenticate: Basic. When false, no header is added (default).

fastify.register(require('@fastify/basic-auth'), {
  validate,
  authenticate: true // WWW-Authenticate: Basic
})

fastify.register(require('@fastify/basic-auth'), {
  validate,
  authenticate: false // no authenticate header, same as omitting authenticate option
})

The authenticate option can have a realm key when supplied as an object. If the realm key is supplied, it will be appended to the header value:

fastify.register(require('@fastify/basic-auth'), {
  validate,
  authenticate: {realm: 'example'} // WWW-Authenticate: Basic realm="example"
})

The realm key can also be a function:

fastify.register(require('@fastify/basic-auth'), {
  validate,
  authenticate: {
    realm(req) {
      return 'example' // WWW-Authenticate: Basic realm="example"
    }
  }
})

header String (optional)

The header option specifies the header name to get credentials from for validation.

fastify.register(require('@fastify/basic-auth'), {
  validate,
  header: 'x-forwarded-authorization'
})

License

Licensed under MIT.