Cloudflare Cron Triggers

Cloudflare Cron Triggers

Status: Production Ready ✅ Last Updated: 2025-10-23 Token Savings: ~60% (vs. manual implementation) Errors Prevented: 6 documented issues

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Auto-Trigger Keywords

This skill automatically activates when Claude detects:

Core Technologies

• cloudflare cron
• cron triggers
• scheduled workers
• scheduled handler
• cloudflare scheduled
• worker cron
• wrangler cron

Handler Keywords

• scheduled() handler
• scheduled event
• ScheduledController
• scheduled function
• export scheduled
• async scheduled

Configuration Keywords

• triggers.crons
• wrangler.jsonc cron
• cron configuration
• wrangler triggers
• cron expression
• cron syntax

Use Cases

• periodic tasks
• scheduled tasks
• background jobs
• maintenance tasks
• scheduled execution
• automated tasks
• recurring jobs
• scheduled workflow

Common Errors

• "scheduled handler not found"
• "handler does not export"
• "cron expression invalid"
• "changes not propagating"
• "cron not executing"
• "wrong execution time"
• "UTC timezone"
• "CPU time limit exceeded"

Related Features

• green compute
• workflow triggers
• scheduled maintenance
• data collection
• report generation
• database cleanup

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What This Skill Provides

Complete knowledge domain for Cloudflare Cron Triggers - scheduling Workers to execute periodically using cron expressions.

Key Topics Covered

1. Scheduled Handler Setup

   • Correct ES modules format
   • Handler naming requirements
   • TypeScript types

2. Cron Expression Syntax

   • 5-field format explanation
   • Common patterns library
   • Validation guidelines

3. Configuration

   • wrangler.jsonc setup
   • Multiple cron triggers
   • Environment-specific schedules

4. Testing

   • Local development with --test-scheduled
   • /__scheduled endpoint
   • Debugging scheduled handlers

5. Integration Patterns

   • Standalone scheduled Worker
   • Combined with Hono (fetch + scheduled)
   • Multiple schedules with routing
   • Accessing environment bindings
   • Triggering Workflows

6. UTC Timezone Handling

   • All crons run on UTC
   • Time zone conversion guide
   • DST considerations

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Known Issues Prevented

Issue	Error Message	Prevention
Propagation Delay	Changes not taking effect	Document 15-minute wait time
Wrong Handler Name	"Handler does not export"	Enforce exact scheduled name
UTC Confusion	Cron runs at wrong time	Timezone conversion guide
Invalid Syntax	Cron doesn't execute	Validation with Crontab Guru
Service Worker Format	"Must use ES modules"	ES modules examples
CPU Limits	"CPU time exceeded"	Limits configuration guide

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Quick Example

// src/index.ts
export default {
  async scheduled(
    controller: ScheduledController,
    env: Env,
    ctx: ExecutionContext
  ): Promise<void> {
    console.log('Cron executed:', controller.cron);
    await performScheduledTask(env);
  },
};

// wrangler.jsonc
{
  "triggers": {
    "crons": ["0 * * * *"]  // Every hour
  }
}

# Test locally
npx wrangler dev --test-scheduled
curl "http://localhost:8787/__scheduled?cron=0+*+*+*+*"

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When to Use This Skill

Use this skill when:

• ✅ Setting up scheduled Workers for the first time
• ✅ Configuring cron expressions in wrangler.jsonc
• ✅ Combining scheduled handlers with Hono
• ✅ Testing cron triggers locally
• ✅ Converting local timezone to UTC
• ✅ Handling multiple cron schedules
• ✅ Troubleshooting cron execution issues
• ✅ Integrating crons with Workflows
• ✅ Enabling Green Compute for scheduled tasks
• ✅ Understanding ScheduledController API

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Official Documentation

• Cloudflare Docs: https://developers.cloudflare.com/workers/configuration/cron-triggers/
• Scheduled Handler API: https://developers.cloudflare.com/workers/runtime-apis/handlers/scheduled/
• Cron Examples: https://developers.cloudflare.com/workers/examples/cron-trigger/

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Related Skills

• cloudflare-worker-base - Required for Worker setup
• cloudflare-workflows - For long-running scheduled tasks
• cloudflare-queues - For async processing triggered by crons
• cloudflare-d1 - For database operations in scheduled handlers

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License: MIT Maintainer: Claude Skills Maintainers | maintainers@example.com