Overview

Set up recurring tasks to run on an interval with Begin scheduled functions.

Scheduled functions enable you to do things like regularly back up your application's database, or generate monthly reports based on user interactions. They are the serverless equivalent of a cron job.

Provisioning new scheduled functions

The app.arc file in the root of your project is where you define all of your app's infrastructure as code. Add an entry to the @scheduled section to provision a new scheduled function.

@scheduled
data-backup rate(1 week)

Above is an example of a scheduled function data-backup entry with a rate specified rate(1 week).

⚠️ Scheduled function names are lowercase alphanumeric and can contain dashes. They must declare a rate with a number, and a time period with the appropriate singular / plural form, e.g. rate(1 day), rate(2 weeks)

Read more about the rate syntax here

Now generate a scheduled function handler by running the local sandbox server with npm start. The sandbox server generates scheduled function handlers in src/scheduled.

Pushing the changes made to your app's app.arc file initiates a build that provisions your new scheduled function infrastructure when all specified build steps succeed.

Verify the new scheduled function provisioning on your app's scheduled functions page.

This scheduled function is now available in your app's staging environment; the next production deploy provisions your app's production environment.

Congratulations! You now know how to create scheduled functions.

Scheduled functions in action

Think of scheduled functions as a job you want to do every so often.

One such job you might want to do is give yourself a daily affirmation. Let's walk through one way to implement this:

1. Add a scheduled function named affirm with a rate of 1 day to your app.arc file by adding: affirm rate(1 day)
2. Generate a boilerplate handler with npm start
3. Edit the file src/scheduled/affirm/index.js

// Handler function
exports.handler = async function affirmation(event) {
  console.log('You are good enough, smart enough, and doggone it people like you!')
  return
}

Limits

In the Begin free-tier, scheduled functions are limited in the following ways:

• They can run no more frequently than once every 6 hours
• 30 seconds of execution time

Begin paid-tier apps are not limited in these ways.

Another important thing to note: AWS does not guarantee the exact time of execution. So while you can request a scheduled function runs twice daily, you cannot specify that it run at noon and midnight – it may always run at 2:04 PM & 2:04 AM, for example.

Removing scheduled functions

Modify your app.arc file to remove scheduled functions from your app. Find the @scheduled pragma, then delete the name of the scheduled function you wish to remove.

Push the updated app.arc file, and the deleted scheduled functions get removed from staging. Scheduled functions get removed from production after the next production deploy.

⚠️ Remember to remove the deleted scheduled function's folder from src/scheduled as well.