Netlify serverless function that sends a warning email / SMS if the bandwidth is close to the specified limits.

warn-bandwidth.ts

// This Netlify serverless function will send a warning email / SMS if the bandwidth is close to the specified limits.
// Many environment variables need to be set in order for this function to work:
// - MJ_API_KEY (Mailjet API key)
// - MJ_API_SECRET (Mailjet API secret)
// - SINCH_SERVICE_PLAN_ID (Sinch service plan ID)
// - SINCH_API_TOKEN (Sinch API token)
// - SINCH_NUMBER (Sinch phone number)
// - SINCH_TO_NUMBER (Sinch phone number to send the SMS to)
// - NETLIFY_ACCESS_TOKEN (Netlify access token) - generate one at https://app.netlify.com/sites/{your-site-name}/settings/general#access-control
// - NETLIFY_API_BANDWIDTH_URL (Netlify API bandwidth URL) - should have this pattern: https://api.netlify.com/access-control/bb-api/api/v1/accounts{your-account-id}/bandwidth

// It's recommended to set this up as an hourly scheduled function in your netlify.toml file:
// # ./netlify.toml
// # Hourly warn bandwidth function
// [functions."warn-bandwidth"]
// schedule = "@hourly"
import { Handler } from '@netlify/functions'
import Mailjet from 'node-mailjet'

// Note: Warning thresholds must be defined in ascending order!
const warningThresholds = [25, 50, 75, 99]
// The threshold for sending an SMS (greater than or equal to)
const smsThreshold = 75

const sendWarningEmail = async (threshold: number, percentage: number, periodEndDate: string) => {
  const mailjet = Mailjet.apiConnect(process.env.MJ_APIKEY_PUBLIC || '', process.env.MJ_APIKEY_PRIVATE || '')
  try {
    await mailjet.post('send', { version: 'v3.1' }).request({
      Messages: [
        {
          From: {
            Email: 'yourtoemail@email.com',
            Name: 'From Name'
          },
          To: [
            {
              Email: 'yourtoemail@email.com',
              Name: 'To Name'
            }
          ],
          Subject: `WARNING: Your Netlify bandwidth has exceeded ${threshold}%!`,
          TextPart: `WARNING: Your Netlify bandwidth usage has exceeded ${threshold} and is currently at ${percentage}%! Your bandwidth allocation renews on ${periodEndDate}.`,
          HTMLPart: `WARNING: Your Netlify bandwidth usage has exceeded ${threshold} and is currently at ${percentage}%! Your bandwidth allocation renews on ${periodEndDate}.`
        }
      ]
    })
    console.log(`Warning email successfully sent for exceeding ${threshold}% threshold.`)
  } catch (err: any) {
    console.log('Error sending warning email', err.statusCode)
  }
}

const sendSMS = async (threshold: number, percentage: number, periodEndDate: string) => {
  try {
    const resp = await fetch('https://us.sms.api.sinch.com/xms/v1/' + process.env.SINCH_SERVICE_PLAN_ID + '/batches', {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        Authorization: 'Bearer ' + process.env.SINCH_API_TOKEN
      },
      body: JSON.stringify({
        from: process.env.SINCH_NUMBER,
        to: [process.env.SINCH_TO_NUMBER],
        body: `WARNING: Your Netlify bandwidth usage has exceeded ${threshold} and is currently at ${percentage}%! Your bandwidth allocation renews on ${periodEndDate}.`
      })
    })
    const data = await resp.json()
    console.log(data)
  } catch (err: any) {
    console.log('Error sending SMS', err)
  }
}

const warnIfBandwidthExceeded = async () => {
  const netlifyAuth = `Bearer ${process.env.NETLIFY_ACCESS_TOKEN}`
  const bandwidthUrl = `${process.env.NETLIFY_API_BANDWIDTH_URL}`
  const response = await fetch(bandwidthUrl, {
    method: 'GET',
    headers: {
      'User-Agent': 'YourApp (youremail@email.com)',
      Authorization: netlifyAuth
    }
  })
  const data = await response.json()
  if (data.used && data.included && data.period_end_date) {
    const used = data.used
    const included = data.included
    const percentage = Math.round((used / included) * 100)
    const periodEndDate = new Date(data.period_end_date).toLocaleDateString()
    for (const threshold of warningThresholds) {
      if (percentage > threshold) {
        sendWarningEmail(threshold, percentage, periodEndDate)
        if (smsThreshold >= 75) {
          sendSMS(threshold, percentage, periodEndDate)
        }
        return
      }
    }
  }
}

const handler: Handler = async () => {
  try {
    await warnIfBandwidthExceeded()
    return {
      statusCode: 200,
      body: 'OK'
    }
  } catch (error) {
    console.log(error)
    return {
      statusCode: 500,
      body: 'Unknown error'
    }
  }
}

export { handler }