fargito / cdk-scheduler

cdk-scheduler

A CDK construct to schedule events precisely ⏱

This construct enables you to trigger an event at a given time on a serverless architecture.

You should use cdk-scheduler if you need to trigger an event at a precise time (down to the second) on your AWS application.

Install

To install with npm:

npm install cdk-scheduler

To install with yarn:

yarn add cdk-scheduler

Usage

cdk-scheduler is powered by SQS feature to delay events up to 15 minutes. A lambda is scheduled to query a DynamoDB Table every 15 minutes, it pushes every events scheduled in the next 15 minutes to SQS with a delay corresponding the desired publication date.

Usage example with CDK - Typescript

You can check out the full implementation example in app.ts.

import { Scheduler } from 'cdk-scheduler';

class AppStack extends Stack {
  constructor(scope: Construct, id: string) {
    super(scope, id);

    // Create Scheduler Construct
    const schedulerLib = new Scheduler(this, 'scheduler-lib');

    // Grant writing role to Dynamo DB to your service that will
    const dynamoDbApiIntegrationRole = new Role(
      this,
      'DynamoDbApiIntegrationRole',
      { assumedBy: new ServicePrincipal('apigateway.amazonaws.com') },
    );

    schedulerLib.schedulerTable.grantWriteData(dynamoDbApiIntegrationRole);

    // Add an integration tool such as Dynamo integration or Lambda
    const integration = new DynamoDBPutItemIntegration({
      partitionKey: schedulerLib.partitionKeyValue,
      table: schedulerLib.schedulerTable,
      role: dynamoDbApiIntegrationRole,
    });

    const restApi = new RestApi(this, 'RestApi');

    const addScheduledEventModel = restApi.addModel('AddScheduledEventModel', {
        ...
    });

    restApi.root.addMethod('POST', integration, {
      methodResponses: [{ statusCode: '200' }],
      requestModels: {
        'application/json': addScheduledEventModel,
      },
      requestValidatorOptions: {
        validateRequestBody: true,
        validateRequestParameters: true,
      },
      // authorizer: new RequestAuthorizer(stack, 'MyAuthorizer', {}),
    });
  }
}

const app = new App();
new AppStack(app, 'AppStack');

For the scheduler to function properly the elements added to DynamoDB must have the following attributes:

Attribute	Type	Description
pk	string	The primary key is always the same. Its value is the attribute partitionKey available in the construct instance
sk	string	The secondary key should start with the timestamp at which you wish to publish the event. You can concatenate with a unique id to be sure you do not have duplicates if you separate them with a #. For instance: ✅ 1649434680000#d66727f2-9df7-41b7-b2f8-211eb5581640 is a correct secondary key. ❌ 20220422-16:47:00:00Z00#66727f2-9df7-41b7-b2f8-211eb5581640 will never be read.
payload	map	This an object, to the format of your need. This payload will be sent in the event once it's published. Use this to detail the action you want to execute a the scheduled time