Mar 27, 2021

Create Scheduled Cron Jobs with Cloud Functions for Firebase

#Firebase

Introduction

When you need to run code periodically, Cloud Functions for Firebase can help. It’s handy for tasks that must run at fixed times.

Use cases

  • Aggregate Firestore user data once per day
  • Delete obsolete data

How it works

Internally, the cron service Cloud Scheduler publishes a message to a Pub/Sub topic. A Cloud Function subscribes to that topic to schedule execution.

Installation

Switch to the Blaze plan

This isn’t available on the free plan; switch to the pay‑as‑you‑go Blaze plan.

Install tools

$ npm install -g firebase-tools

Log in: 

$ firebase login

Initialize: 

$ firebase init functions

Writing functions

To set a region, use functions.region. Example that runs every minute:

Intervals are specified using either the cron schedule format or the App Engine cron format. 

exports.scheduledFunction = functions.region('asia-northeast1')
  .pubsub.schedule('every 1 minutes')
  .timeZone('Asia/Tokyo')
  .onRun(() => {
    console.info('hello world');
  });

Deploy: 

$ firebase deploy --only functions

After deployment, the scheduled job appears under Functions as shown below.

Image

References

Official Firebase docs (Japanese)