Scheduling Cloud Functions for Firebase (cron)

The Cloud Functions for Firebase team is pleased to provide a turnkey solution for secure, scheduled functions using Firebase tools and SDKs.

One of the most common questions about Google Cloud Functions is how to schedule a function for regular execution, similar to a cron job. In the past, the Firebase team recommended solutions involving App Engine or third party schedulers as a scheduling mechanism to invoke a function, which works fine. However, solutions that involve the invocation of an HTTP function aren’t fully secure, because the HTTP endpoint URL is effectively public and accessible to anyone who knows that URL. And, solutions that involve creating and sending messages to a Cloud Pub/Sub endpoint can be difficult to manage.

Recently, Google Cloud released Cloud Scheduler, which allows you to schedule HTTP requests or Cloud Pub/Sub messages to functions that you deploy. You can follow a tutorial for getting that set up in your project, if you like. But today, it gets even easier than that, and it doesn’t require working with the Google Cloud console.

Firebase now supports a new type of Pub/Sub function, built on top of Cloud Scheduler, that automatically configures Cloud Scheduler, along with a Pub/Sub topic, that invokes a function that you define using the Cloud Functions for Firebase SDK.

If you’re using version 2.3.0 of the firebase-functions NodeJS module, along with 6.7.0 of the Firebase CLI, you can now define functions that use Google Scheduler’s standard cron syntax like this:

export scheduledFunctionCrontab =
functions.pubsub.schedule('5 11 * * *').onRun((context) => {
    console.log('This will be run every day at 11:05 AM UTC!');

You can schedule invocations using an English description as well:

export scheduledFunctionPlainEnglish =
functions.pubsub.schedule('every 5 minutes').onRun((context) => {
    console.log('This will be run every 5 minutes!');

To get started with scheduled functions using Firebase tools, navigate to the documentation, and check out this sample available in GitHub. Your project must be on the Blaze payment plan, as Cloud Scheduler and Pub/Sub require billing information. Each Cloud Scheduler job costs $0.10 (USD) per month, and there is an allowance of three free jobs per Google account. Besides the normal costs for Cloud Functions, the costs for this feature are the same as if you set up the underlying infrastructure manually - for more information, check out the full pricing information for Cloud Scheduler and Cloud PubSub.