A Discord app with Fastify!

// app.js
module.exports = function app (fastify, opts, next) {
  fastify.get('/', function handler (request, reply) {
    reply.send('hello world')
  })
  next()
}

// app.js
module.exports = function app (fastify, opts, next) {
  ...
  // every plugin must be registered
  fastify.register(require('fastify-static'), {
    root: path.join(__dirname, '../pages'), // the pages are stored in a directory
    serve: false // we don't want to expose only the static file because we do it ourself!
  })

  // everytime the user loads the site root, the homepage will be sent
  fastify.get('/', function serveHtml (request, reply) {
    reply.sendFile('homepage.html')
  })

  // and if the user types a wrong URL, the homepage will be loaded as a fallback
  fastify.setNotFoundHandler(function letsGoToHomepage (request, reply) {
    reply.redirect('/')
  })
  ...
}

// app.js
module.exports = function app (fastify, opts, next) {
  ...
  // this schema is useful to get clear error on startup. 
  // So when you don't have a valid Env configured you will know WHY!
  const schema = {
    type: 'object',
    required: ['PORT', 'DISCORD_CLIENT_ID', 'DISCORD_SECRET'],
    properties: {
      BASE_URL: { type: 'string' },
      PORT: { type: 'integer', default: 3000 },
      DISCORD_CLIENT_ID: { type: 'string' },
      DISCORD_SECRET: { type: 'string' },
      DISCORD_PERMISSION: { type: 'string' }
    }
  }

  // register the plugin that will load the data
  fastify.register(require('fastify-env'), { schema, dotenv: true })
  ...

BASE_URL=http://localhost:3000
DISCORD_CLIENT_ID=1234567890
DISCORD_SECRET=ABC123ABC

// auth.js
const oauth2 = require('fastify-oauth2')

module.exports = function auth (fastify, opts, next) {
  // fastify.config has been added by fastify-env - thanks to decorators!

  // register the OAUTH2 plugin.. and it is done!
  fastify.register(oauth2, {
    name: 'discordOAuth2',
    credentials: {
      client: {
        id: fastify.config.DISCORD_CLIENT_ID,
        secret: fastify.config.DISCORD_SECRET
      },
      auth: oauth2.DISCORD_CONFIGURATION
    },
    scope: ['identify'],
    startRedirectPath: '/discord',
    callbackUri: 'http://localhost:3000/discord/callback' // this URL must be exposed
  })

  // the callbackUri implementation
  fastify.get('/discord/callback', async function (request, reply) {
    // the response will have the `code`
    const token = await this.discordOAuth2.getAccessTokenFromAuthorizationCodeFlow(request)

    // in async handler it is possible to just return the payload!
    return token
  })

  next()
}

// app.js
module.exports = function bot (fastify, opts, next) {
  ...
  fastify.register(require('point-of-view'), {
    engine: {
      handlebars: require('handlebars')
    }
  })

  // now we can manage all unexpected errors in a nicer way!
  fastify.setErrorHandler(function (error, request, reply) {
    reply.view('/pages/error.hbs', error)
  })
  ...

// auth.js
module.exports = function auth (fastify, opts, next) {
  ...
  fastify.get('/discord/callback', async function (request, reply) {
    const token = await this.discordOAuth2.getAccessTokenFromAuthorizationCodeFlow(request)

    // the token can be used to get the user data
    const userData = await got.get('https://discord.com/api/users/@me', {
      responseType: 'json',
      headers: {
        authorization: `${token.token_type} ${token.access_token}`
      }
    })

    // show the nice user profile
    reply.view('/pages/who-am-i.hbs', userData.body)
  })
  ...

// app.js
module.exports = function app (fastify, opts, next) {
  ...
  fastify.register(require('fastify-helmet'), {
    contentSecurityPolicy: {
      directives: {
        defaultSrc: ["'self'"],
        baseUri: ["'self'"],
        fontSrc: ["'self'", 'https:', 'data:'],
        frameAncestors: ["'self'"],
        imgSrc: ["'self'", 'data:', 'via.placeholder.com', 'cdn.discordapp.com'], // list all the good source
        objectSrc: ["'none'"],
        scriptSrc: ["'self'", 'kit.fontawesome.com'], // list all the good source
        scriptSrcAttr: ["'none'"],
        styleSrc: ["'self'", 'https:', "'unsafe-inline'"]
      }
    }
  })
  ...

const t = require('tap')
const nock = require('nock')
const Fastify = require('fastify')

const app = require('../app.js')

t.test('the application starts', async t => {
  const server = Fastify()
  server.register(app) // it is necessary to register the app entrypoint

  // then with .inject it is possible to execute HTTP requests to the server without starting it!
  const res = await server.inject('/')
  t.equal(res.payload, fs.readFileSync('./pages/homepage.html', 'utf8'))
})

"start": "fastify start -a 0.0.0.0 app.js",

heroku login
# add a new remote to my repository
heroku git:remote -a fastify-discord-app-demo
# check the remote addition
git remote -v
# push your master
git push heroku master
# in case your branch is not master:
git push heroku local-branch:master