cron-workflow

cron-workflow

An experimental package for building cron jobs with Cloudflare Workflows

Installation

npm install cron-workflow

Define a cron workflow

Extend CronWorkflow and implement the onTick() handler (and optionally add onInit/onFinalize hooks):

// src/CleanupCron.cron.ts
import { CronContext, CronFinalizeContext, CronWorkflow } from 'cron-workflow'

export class CleanupCron extends CronWorkflow<Env> {
  override schedule = '0 * * * *' // defaults to every 5 minutes

  // optional
  override async onInit({ step }: CronContext) {
    await step.do('log start', async () => console.log('starting cleanup'))
  }

  // required
  override async onTick({ step }: CronContext) {
    await step.do('delete stale records', async () => {
      // your cron work goes here
    })
  }

  // optional
  override async onFinalize({ step, error }: CronFinalizeContext) {
    await step.do('log result', async () => {
      console.log(error ? 'cleanup failed' : 'cleanup finished')
    })
  }
}

Each hook receives the underlying WorkflowStep, so you can wrap work in step.do() steps, call step.sleep(), etc. Learn more here.

Configure your Worker

Add the workflow and required Durable Object binding to wrangler.jsonc:

{
  "workflows": [
    // note: binding MUST match class_name
    { "name": "CleanupCron", "class_name": "CleanupCron", "binding": "CleanupCron" }
  ],
  "durable_objects": {
    "bindings": [{ "name": "CronController", "class_name": "CronController" }]
  },
  "migrations": [{ "tag": "v1", "new_sqlite_classes": ["CronController"] }]
}

Then re-export both your cron class and the provided CronController in your Worker entrypoint:

// src/index.ts
export { CronController } from 'cron-workflow'
export { CleanupCron } from './crons/CleanupCron.cron'

Although CronController is a stub today, shipping it now avoids a breaking change once controller features ship.

Bootstrapping a run

Currently, it is necessary to trigger the Workflow the first time you deploy a new CronWorkflow for it to start running:

npx wrangler workflows trigger CleanupCron

From there the workflow will create a new instance for each run based on schedule.

Current limitations

• Changing schedule only takes effect after the current workflow run finishes. You can terminate the instance and trigger a new one to apply it immediately. In the future, CronController will handle this automatically.
• CronController is currently a no-op, but will soon be required to ensure cron reliability and automatically handle schedule updates.