Kuron

A lightweight framework for Cloudflare Workers scheduled jobs with a Hono-inspired API.

Features

• 🎯 Hono-like API - Familiar and intuitive interface
• 🔗 Middleware Support - Chain middleware for logging, auth, etc.
• 🎭 Error Handling - Global error handler with context
• 🔐 Type Safety - Full TypeScript support with type inference
• 🎨 Context Variables - Share data across middleware and handlers
• ⚡ Zero Dependencies - Built on standard Cloudflare Workers APIs

Installation

npm install kuron

Quick Start

import { Cron } from 'kuron';

const cron = new Cron()
  .schedule('0 15 * * *', async (c) => {
    console.log('☕️ Good afternoon! Time for your daily 3 PM cleanup routine ✨');
    // Your job logic here
  });

export default cron;

Or using a named function for better logging:

import { Cron } from 'kuron';

const cron = new Cron()
  .schedule('0 15 * * *', async function afternoonCleanup(c) {
    console.log('Running job:', c.name); // "afternoonCleanup"
    // Your job logic here
  });

export default cron;

API Reference

new Cron<Environment>()

Creates a new Cron instance.

Type Parameters:

• Environment: Object with Bindings and Variables properties (similar to Hono)

.schedule(pattern, handler)

Register a scheduled job with a cron pattern.

Parameters:

• pattern: Cron pattern string (e.g., '0 15 * * *')
• handler: Async function to execute when the cron triggers

Returns: this (chainable)

cron.schedule('*/5 * * * *', async (c) => {
  console.log('Runs every 5 minutes');
});

.use(middleware)

Register middleware to run before job handlers.

Parameters:

• middleware: Function with signature (c, next) => Promise<void>

Returns: this (chainable)

// Logging middleware
cron.use(async (c, next) => {
  console.log('Job started:', c.cron, c.name ? `(${c.name})` : '');
  const start = Date.now();
  await next();
  const duration = Date.now() - start;
  console.log(\`Job completed in \${duration}ms\`);
});

// Auth middleware
cron.use(async (c, next) => {
  if (!c.env.API_KEY) {
    throw new Error('API_KEY not configured');
  }
  await next();
});

.onError(handler)

Register a global error handler.

Parameters:

• handler: Function with signature (error, context) => Promise<void>

Returns: this (chainable)

cron.onError((err, c) => {
  console.error('Job failed:', {
    cron: c.cron,
    name: c.name,
    error: err.message,
    stack: err.stack,
  });
  
  // Optional: Send to error tracking service
  // await sendToSentry(err);
});

Context Object (c)

The context object passed to handlers and middleware:

interface CronContext<E> extends ScheduledController {
  // Environment bindings (secrets, KV namespaces, etc.)
  env: E['Bindings'];
  
  // Custom variables shared between middleware and handlers
  var: E['Variables'];
  
  // Cloudflare Workers execution context
  executionCtx: ExecutionContext;
  
  // Cron pattern for this job (e.g., "0 15 * * *")
  cron: string;
  
  // Name of the handler function (if provided as a named function)
  name?: string;
  
  // ScheduledController properties (inherited)
  // - scheduledTime: number
  // - noRetry(): void
  
  // Get a variable
  get: <K extends keyof E['Variables']>(key: K) => E['Variables'][K];
  
  // Set a variable
  set: <K extends keyof E['Variables']>(key: K, value: E['Variables'][K]) => void;
}

Properties:

• env: Access environment bindings (secrets, KV, D1, etc.)
• var: Access/modify custom variables
• executionCtx: Cloudflare Workers ExecutionContext for waitUntil() and passThroughOnException()
• cron: The cron pattern string that triggered this job
• name: Optional name of the handler function (captured from function.name)
• scheduledTime: Unix timestamp (ms) when the job was scheduled (inherited from ScheduledController)
• noRetry(): Call to prevent automatic retries on failure (inherited from ScheduledController)
• get(key): Get a custom variable
• set(key, value): Set a custom variable

Advanced Examples

Multiple Jobs

// Using anonymous functions
const cron = new Cron<Environment>()
  .schedule('0 0 * * *', async (c) => {
    console.log('Daily midnight job');
  })
  .schedule('0 12 * * *', async (c) => {
    console.log('Daily noon job');
  })
  .schedule('0 0 * * 0', async (c) => {
    console.log('Weekly Sunday job');
  });

Middleware Chain

const cron = new Cron<Environment>()
  // Timing middleware
  .use(async (c, next) => {
    const start = Date.now();
    await next();
    console.log(\`Duration: \${Date.now() - start}ms\`);
  })
  // Setup middleware
  .use(async (c, next) => {
    c.set('startTime', new Date().toISOString());
    await next();
  })
  // Cleanup middleware
  .use(async (c, next) => {
    await next();
    console.log('Cleanup completed');
  })
  .schedule('0 * * * *', async (c) => {
    const startTime = c.get('startTime');
    console.log('Job started at:', startTime);
  });

Sharing Data via Variables

interface MyEnvironment {
  Bindings: Env;
  Variables: {
    db: Database;
    requestId: string;
  };
}

const cron = new Cron<MyEnvironment>()
  .use(async (c, next) => {
    // Initialize DB connection in middleware
    const db = await initDatabase(c.env.DATABASE_URL);
    c.set('db', db);
    c.set('requestId', crypto.randomUUID());
    
    await next();
  })
  .schedule('0 15 * * *', async (c) => {
    // Access DB from middleware
    const db = c.get('db');
    const requestId = c.get('requestId');
    
    console.log('Request ID:', requestId);
    await db.query('...');
  });

Error Recovery

const cron = new Cron<Environment>()
  .use(async (c, next) => {
    try {
      await next();
    } catch (err) {
      console.error('Middleware caught error:', err);
      // Optionally rethrow or handle
      throw err;
    }
  })
  .schedule('0 * * * *', async (c) => {
    // Job logic that might fail
    await riskyOperation();
  })
  .onError(async (err, c) => {
    // Global error handling
    await reportToErrorService({
      error: err,
      cron: c.cron,
      name: c.name,
      timestamp: new Date().toISOString(),
    });
  });

Integration with Hono

import { OpenAPIHono } from '@hono/zod-openapi';
import { Cron } from './lib/cron';

const app = new OpenAPIHono<Environment>()
  .get('/health', (c) => c.text('OK'));

const cron = new Cron<Environment>()
  .schedule('0 15 * * *', async (c) => {
    await syncData(c.env);
  });

export default {
  fetch: app.fetch,
  scheduled: cron.scheduled,
};

Cron Pattern Syntax

Cloudflare Workers supports standard cron syntax:

┌───────────── minute (0 - 59)
│ ┌───────────── hour (0 - 23)
│ │ ┌───────────── day of the month (1 - 31)
│ │ │ ┌───────────── month (1 - 12)
│ │ │ │ ┌───────────── day of the week (0 - 6) (Sunday to Saturday)
│ │ │ │ │
* * * * *

Examples:

• 0 15 * * * - Daily at 3:00 PM UTC
• */5 * * * * - Every 5 minutes
• 0 0 * * 0 - Every Sunday at midnight
• 0 0 1 * * - First day of every month at midnight
• 30 2 * * 1-5 - 2:30 AM UTC, Monday through Friday

TypeScript Tips

Type Inference

The Cron framework automatically infers types from your Environment:

interface MyEnvironment {
  Bindings: {
    DATABASE_URL: string;
  };
  Variables: {
    userId: string;
  };
}

const cron = new Cron<MyEnvironment>();

cron.schedule('0 * * * *', async (c) => {
  // TypeScript knows these types!
  c.env.DATABASE_URL; // string
  c.var.userId;       // string
  c.get('userId');    // string
  c.cron;             // "0 * * * *" (exact literal type!)
  c.name;             // string | undefined
  c.scheduledTime;    // number
});

Pattern Type Tracking

Similar to how Hono tracks route paths, the Cron framework tracks cron patterns in the type system:

// Single pattern
const dailyCron = new Cron<MyEnvironment>()
  .schedule('0 15 * * *', async (c) => {
    // c.cron has type: "0 15 * * *"
    console.log(c.cron);
  });

// Type: Cron<MyEnvironment, "0 15 * * *">

// Multiple patterns
const multiCron = new Cron<MyEnvironment>()
  .schedule('0 * * * *', async (c) => {
    // c.cron has type: "0 * * * *"
  })
  .schedule('0 0 * * *', async (c) => {
    // c.cron has type: "0 0 * * *"
  });

// Type: Cron<MyEnvironment, "0 * * * *" | "0 0 * * *">

// Extract pattern types
type ExtractPatterns<T> = T extends Cron<any, infer P> ? P : never;
type Patterns = ExtractPatterns<typeof multiCron>;
// Result: "0 * * * *" | "0 0 * * *"

Benefits:

• 🎯 Type Safety: Catch typos in pattern comparisons at compile time
• 💡 IntelliSense: Better autocomplete and hover information
• 📚 Self-Documenting: See all patterns in type hints
• 🔄 Safe Refactoring: Rename patterns with confidence

Best Practices

1. Use Named Functions: Define handlers as named functions instead of anonymous arrow functions for better logging and debugging via c.name
2. Use Middleware for Common Logic: Extract shared setup, logging, and cleanup into middleware
3. Handle Errors Gracefully: Always implement .onError() for production workloads
4. Keep Jobs Idempotent: Jobs should be safe to retry in case of failures
5. Use ExecutionContext: Call c.executionCtx.waitUntil() for background tasks
6. Log Extensively: Use middleware for consistent logging across all jobs, including c.name and c.cron
7. Test Locally: Use Wrangler to test scheduled triggers locally

Comparison with Hono

| Feature | Hono | Cron Framework | |---------|------|----------------| | Entry point | app.fetch | cron.scheduled | | Routing | URL patterns | Cron patterns | | Context | Request-based | Schedule-based | | Middleware | ✅ | ✅ | | Variables | ✅ | ✅ | | Error handling | ✅ | ✅ | | Type safety | ✅ | ✅ |

License

MIT