@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 you can use inside any hook before your 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 will call the Fastify generic error handler with an error. @fastify/basic-auth sets the err.statusCode property to 401.

In order 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 containing characters outside the US-ASCII character set will cause interoperability issues, unless both communication partners agree on what character encoding scheme is to be used. If utf8 is set to true the server will send the 'charset' parameter to indicate a preference of "UTF-8", increasing the probability that clients will switch to that encoding.

strictCredentials (optional, default: true)

If strictCredentials is set to false the authorization header can contain additional whitespaces at the beginning, in the midde and at the end of the authorization header. This is a fallback option to ensure the same behaviour 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 may 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 may 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)

When supplied, the authenticate option will cause the WWW-Authenticate header to be added. It may also be used to set the realm value.

This can be useful in situations where we want to trigger client-side authentication interfaces - for instance the browser authentication dialog.

As a boolean setting authenticate to true will set a header like so: WWW-Authenticate: Basic. When false, no header is added. This is the 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
})

When supplied as an object the authenticate option may have a realm key.

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 could also be a function:

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

header String (optional)

When supplied, the header option is the name of the header to get credentials from for validation.

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

License

Licensed under MIT.