Schedule functions

If you want to schedule functions to run at specified times, use the onSchedule handler to create a Pub/Sub topic that uses Cloud Scheduler to trigger events on that topic.

Before you begin

Though billing is required, you can expect the overall cost to be manageable, as each Cloud Scheduler job costs $0.10 (USD) per month, and there is an allowance of three jobs per Google account, at no charge. Use the Blaze pricing calculator to generate a cost estimate based on your projected usage.

The Pub/Sub and Cloud Scheduler APIs must be enabled for your project. These should already be enabled for most Firebase projects; you can verify in the Google Cloud console.

Important: Cloud Scheduler used to require that your project have a Google App Engine app. During its setup you were prompted to select a location, and this location became your project's location for default Google Cloud resources (Cloud Scheduler being one of these resources). This location is used for resources in your project that have an association with App Engine, including your default Cloud Firestore database instance and your default Cloud Storage bucket (specifically with the name format *.appspot.com).

However, now that Cloud Scheduler and recently provisioned default Cloud Storage buckets (with the name format *.firebasestorage.app) no longer have a dependency on App Engine, you only need to consider this location if you're using 1st gen scheduled functions and *.appspot.com buckets.

Write a scheduled function

In Cloud Functions for Firebase, scheduling logic resides in your functions code, with no special deploy-time requirements. To create a scheduled function, use functions.pubsub.schedule('your schedule').onRun((context)). For example, to run a function every five minutes with App Engine cron.yaml syntax, do something like this:

exports.scheduledFunction = functions.pubsub.schedule('every 5 minutes').onRun((context) => {
  functions.logger.log('This will be run every 5 minutes!');
  return null;
});

Both Unix Crontab and App Engine syntax are supported by Cloud Scheduler. For example, to use Crontab to select a specific timezone in which to run a scheduled function, do something like this:

exports.scheduledFunctionCrontab = functions.pubsub.schedule('5 11 * * *')
  .timeZone('America/New_York') // Users can choose timezone - default is America/Los_Angeles
  .onRun((context) => {
  functions.logger.log('This will be run every day at 11:05 AM Eastern!');
  return null;
});

The value for timeZone must be a time zone name from the tz database. See the Cloud Scheduler reference for more information on supported properties.

The context object for a scheduled function includes information about the Pub/Sub event that triggered it. For example:

{
  "resource": {
    "name": "projects/PROJECT_ID/topics/PROJECT_TOPIC",
    "service": "pubsub.googleapis.com",
    "type": "type.googleapis.com/google.pubsub.v1.PubsubMessage"
  },
  "timestamp": "YYYY-MM-DDTHH:MM:SS.sssZ",
  "eventType": "google.pubsub.topic.publish",
  "eventId": "EVENT_ID",
  "params": {}
}

Deploy a scheduled function

When you deploy a scheduled function, the related scheduler job and pub/sub topic are created automatically. The Firebase CLI echoes the topic name, and you can view the job and topic in the Google Cloud console. The topic is named according to the following convention:

firebase-scheduled-function_name-region

For example:

firebase-scheduled-scheduledFunctionCrontab-us-east1.