Slack bot who triggers Bitrise, using Google Cloud Function as a messenger

SlackBotToBitrise.js

const rp = require('request-promise-native')

const slackToken = '<SLACK TOKEN>'
const bitriseToken = '<BITRISE API TOKEN>'

const baseBitriseData = {
  hook_info: {
    type: 'bitrise',
    build_trigger_token: bitriseToken
  },
  build_params: {
    branch: 'none',
    workflow_id: 'none'
  },
  triggered_by: 'Slack'
}

const baseBitriseRequest = {
  method: 'POST',
  uri: 'https://app.bitrise.io/app/<BITRISE APP ID>/build/start.json',
  body: 'none',
  json: true
}

function validate(req) {
  if (req.method !== 'POST') {
    const error = new Error('Only POST requests are accepted')
    error.code = 405
    throw error
  }

  const body = req.body

  // Verify that this request came from Slack
  if (!body || body.token !== slackToken) {
    const error = new Error('Nope')
    error.code = 401
    throw error
  }

  if (!(body.text && /^[A-Za-z0-9._+-]+$/g.exec(body.text))) {
    const error = new Error('Nope')
    error.code = 400
    throw error
  }
}

exports.bitrisebuild = (req, res) => {
  return Promise.resolve()
    .then(() => {
      validate(req)

      const buildId = req.body.text
      const bitriseData = baseBitriseData
      const bitriseRequest = baseBitriseRequest

      bitriseData.build_params.branch = buildId
      bitriseData.build_params.workflow_id = buildId

      bitriseRequest.body = bitriseData

      return rp(bitriseRequest).catch(err => {
        console.error(err)
        const error = new Error('Build id not OK')
        error.code = 400
        return Promise.reject(error)
      })
    })
    .then(() => {
      res.send('Building!')
    })
    .catch(err => {
      console.error(err)
      res.status(err.code || 500).send(err)
      return Promise.reject(err)
    })
}