Google Cloud Run functions (Node.js) JavaScript

import * as functions from '@google-cloud/functions-framework';

const GIF = Buffer.from('R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==', 'base64');

functions.http('pixel', (req, res) => {
  if (req.path !== '/pixel.gif') {
    res.sendStatus(404);
    return;
  }
  res.set('Cache-Control', 'no-store').type('gif').send(GIF);
});