set cache headers on uploaded file via cloud function

index.js

const storage = require('@google-cloud/storage')();

exports.setMeta = function (event, doneCb) {
  const file = event.data;
  console.log(`Examing file ${file.name}.`);
  const gcsBucket = storage.bucket(file.bucket);
  const gcsFile = gcsBucket.file(file.name);

  if (file.metageneration === '1') {

    console.log(`File ${file.name} has been freshly uploaded.`);

    return gcsFile
      .setMetadata({
        cacheControl: 'max-age=604800; stale-if-error=86400; stale-while-revalidate=30, public',
      })
      .then(() => {
        console.log(`Metadata set on ${file.name}.`);
        doneCb();
      })
      .catch((e) => {
        console.error(`Error, metadata not set on ${file.name}.`, e);
      });
  } else {
    console.log(`File ${file.name} not new, not setting metadata.`);
    doneCb();
  }
};

package.json

{
  "name": "gcs-setmeta",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "Justin <justin@fiddlyio.com>",
  "license": "ISC",
  "dependencies": {
    "@google-cloud/storage": "^1.5.2"
  }
}