Example Code For Backing Up Google Cloud Storage with Cloud Functions

backup-cloud-function.js

/***
package.json:
{
  "name": "sample-pubsub",
  "version": "0.0.1",
  "dependencies": {
    "@google-cloud/pubsub": "^0.18.0",
    "firebase-admin": "8.0.0"
  }
}
***/

const admin = require('firebase-admin');
admin.initializeApp();
const sourceBucket = admin.storage().bucket("test-product-bucket");
const destBucket = admin.storage().bucket("test-back-up-bucket");


exports.helloPubSub = async (event, context) => {
  	console.log("backup started")
    const d = new Date();
    const dateStr = d.toLocaleDateString();
    console.log(dateStr);

    const [sourceFiles] = await sourceBucket.getFiles({
        prefix: 'data/'
    });

    const sourceFileNames = sourceFiles.map(
        (file) => file.name);

    console.log(dateStr, "# Total", sourceFileNames.length);
	
    let promises = [];
    for (let fileName of sourceFileNames) {
      const copyFilePromise = sourceBucket.file(fileName).copy(destBucket.file(`${dateStr}/${fileName}`));
      promises.push(copyFilePromise);
    }
    await Promise.all(promises);
  	console.log("backup ended")
    return "DONE";
};