Installation

Getting Chronos up and running in your Node.js application is quick and straightforward.

Prerequisites

• Node.js: Version 14 or higher
• MongoDB: Version 4.0 or higher
• TypeScript (optional): For TypeScript projects

Install Chronos

Install Chronos via npm:

npm install chronos-jobs

Or using yarn:

yarn add chronos-jobs

MongoDB Setup

Chronos requires a MongoDB database to store job information. You have several options:

Option 1: Local MongoDB

Install MongoDB locally following the official MongoDB installation guide.

Option 2: MongoDB Cloud (Atlas)

1. Create a free account at MongoDB Atlas
2. Create a new cluster
3. Get your connection string from the cluster dashboard

Option 3: Docker

Run MongoDB using Docker:

docker run --name mongodb -d -p 27017:27017 mongo:latest

Verify Installation

Create a simple test file to verify everything works:

// test-chronos.js
const { Chronos } = require('chronos-jobs');

const scheduler = new Chronos({
  db: { address: 'mongodb://127.0.0.1:27017/test-chronos' }
});

scheduler.define('test job', async (job) => {
  console.log('Test job running!', job.attrs.data);
});

(async () => {
  await scheduler.start();
  await scheduler.now('test job', { message: 'Hello Chronos!' });
  
  // Wait a moment for the job to complete
  setTimeout(async () => {
    await scheduler.stop();
    console.log('Test completed successfully!');
    process.exit(0);
  }, 1000);
})();

Run the test:

node test-chronos.js

You should see:

Test job running! { message: 'Hello Chronos!' }
Test completed successfully!

TypeScript Setup

If you're using TypeScript, Chronos includes built-in type definitions:

import { Chronos } from 'chronos-jobs';

const scheduler = new Chronos({
  db: { address: 'mongodb://127.0.0.1:27017/scheduler' }
});

scheduler.define('typed job', async (job) => {
  // Full type support
  const data = job.attrs.data;
  console.log('Job data:', data);
});

Environment Variables

For production applications, use environment variables for configuration:

const scheduler = new Chronos({
  db: { 
    address: process.env.MONGODB_URI || 'mongodb://127.0.0.1:27017/scheduler',
    options: {
      ssl: process.env.NODE_ENV === 'production'
    }
  }
});

Common Issues

Connection Errors

If you encounter connection issues:

1. Check MongoDB is running: mongosh (or mongo for older versions)
2. Verify connection string: Ensure the database URL is correct
3. Network access: Check firewall settings for MongoDB port (27017)

Permission Issues

For MongoDB Atlas or secured instances:

• Ensure your IP is whitelisted
• Verify username/password in connection string
• Check database access permissions