Example of firebase billing shutdown cloud function

stopBilling.js

// const admin = require('firebase-admin');
const { sendDiscordMessage } = require('./helpers');

const { google } = require('googleapis');
const { GoogleAuth } = require('google-auth-library');

const PROJECT_ID = 'project-name';
const PROJECT_NAME = `projects/${PROJECT_ID}`;
const billing = google.cloudbilling('v1').projects;

/**
 * @return {Promise} Credentials set globally
 */
const _setAuthCredential = () => {
  const client = new GoogleAuth({
    scopes: [
      'https://www.googleapis.com/auth/cloud-billing',
      'https://www.googleapis.com/auth/cloud-platform'
    ]
  });

  // Set credential globally for all requests
  google.options({
    auth: client
  });
};

/**
 * Determine whether billing is enabled for a project
 * @param {string} projectName Name of project to check if billing is enabled
 * @return {bool} Whether project has billing enabled or not
 */
const _isBillingEnabled = async projectName => {
  try {
    const res = await billing.getBillingInfo({
      name: projectName
    });
    // console.log(res);
    return res.data.billingEnabled;
  } catch (e) {
    console.log(
      'Unable to determine if billing is enabled on specified project, assuming billing is enabled'
    );
    return true;
  }
};

/**
 * Disable billing for a project by removing its billing account
 * @param {string} projectName Name of project disable billing on
 * @return {string} Text containing response from disabling billing
 */
const _disableBillingForProject = async projectName => {
  const res = await billing.updateBillingInfo({
    name: projectName,
    resource: {
      billingAccountName: ''
    } // Disable billing
  });
  console.log(res);
  console.log('Billing Disabled');
  return `Billing disabled: ${JSON.stringify(res.data)}`;
};

const stopBilling = async pubsubEvent => {
  console.log('!!!!!running stop billing' /* , pubsubEvent.data */);

  const pubsubData = JSON.parse(
    Buffer.from(pubsubEvent.data, 'base64').toString()
  );

  // console.log(pubsubData);
  console.log('Actual cost amount:', pubsubData.costAmount);
  console.log('Set budget:', pubsubData.budgetAmount);

  if (pubsubData.costAmount <= pubsubData.budgetAmount) {
    console.log('No action necessary.');
    return `No action necessary. (Current cost: ${pubsubData.costAmount})`;
  }

  if (!PROJECT_ID) {
    console.log('no project specified');
    return 'No project specified';
  }

  _setAuthCredential();

  const billingEnabled = await _isBillingEnabled(PROJECT_NAME);
  if (billingEnabled) {
    if (pubsubData.costAmount >= 1000) {
      console.log('disabling billing');

      await sendDiscordMessage(
        'error',
        'Warning',
        `Stopping billing as the current usage is at ${pubsubData.costAmount}, past the budget set at ${pubsubData.budgetAmount}`
      );
      return; /* _disableBillingForProject(PROJECT_NAME); */
    }
  } else {
    console.log('billing already disabled');
    return 'Billing already disabled';
  }
};

exports.stopBilling = stopBilling;

// You need to setup a budget and link it at the pub/sub *topics* 
// Example of message payload sent from the budget trigger at
// https://console.cloud.google.com/cloudpubsub/topic/detail/budgets-control
// {
//     "budgetDisplayName": "name-of-budget",
//     "alertThresholdExceeded": 1.0,
//     "costAmount": 100.01,
//     "costIntervalStart": "2019-01-01T00:00:00Z",
//     "budgetAmount": 100.00,
//     "budgetAmountType": "SPECIFIED_AMOUNT",
//     "currencyCode": "USD"
// }