node version v12.18.1 npm version 6.14.5 cdk version 1.59.0 (build 1d082f4)

cdk-serverless-stack-01.ts

// create an API Gateway endpoint that invokes a Lambda function. This Lambda functions chooses a random number 
// between 0 and 10000, and posts this number to an SQS queue. Another Lambda function picks up this message, 
// and puts the value in DynamoDB

import * as cdk from '@aws-cdk/core';
import { Queue } from '@aws-cdk/aws-sqs';
import { Table, AttributeType } from '@aws-cdk/aws-dynamodb';
import { Function, Runtime, Code } from '@aws-cdk/aws-lambda';
import { RestApi, LambdaIntegration } from '@aws-cdk/aws-apigateway';
import { SqsEventSource } from '@aws-cdk/aws-lambda-event-sources';

export class ServerlessStackStack extends cdk.Stack {
  constructor(scope: cdk.Construct, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    // The code that defines your stack goes here
    const queue = new Queue(this, 'queue', {
      queueName: 'queue'
    });
    const table = new Table(this, 'table', {
      partitionKey: { name: 'id', type: AttributeType.NUMBER }
    });
    const publishFunction = new Function(this, 'publishFunction', {
      runtime: Runtime.NODEJS_10_X,
      handler: 'index.handler',
      code: Code.asset('./handlers/publish'),
      environment: {
        QUEUE_URL: queue.queueUrl
      },
    });
    const api = new RestApi(this, 'api', {
      deployOptions: {
        stageName: 'dev'
      }
    });

    api.root.addMethod('GET', new LambdaIntegration(publishFunction));

    const subscribeFunction = new Function(this, 'subscribeFunction', {
      runtime: Runtime.NODEJS_10_X,
      handler: 'index.handler',
      code: Code.asset('./handlers/subscribe'),
      environment: {
        QUEUE_URL: queue.queueUrl,
        TABLE_NAME: table.tableName
      },
      events: [
        new SqsEventSource(queue)
      ]
    });

    queue.grantSendMessages(publishFunction);
    table.grant(subscribeFunction, "dynamodb:PutItem");
//

  }
}

handler-publish.js

// rename it to index.js and put on ./handlers/publish
const aws = require('aws-sdk');
const sqs = new aws.SQS();

exports.handler = async (event) => {
    const randomInt = Math.floor(Math.random() * Math.floor(10000)).toString();

    const params = {
        QueueUrl: process.env.QUEUE_URL,
        MessageBody: randomInt
    };

    await sqs.sendMessage(params).promise();

    return {
        statusCode: 200,
        body: `Successfully pushed message ${randomInt}!!`
    }
}

handler-subscribe.js

// rename it to index.js and put on ./handlers/subscribe
const aws = require('aws-sdk');
const dynamodb = new aws.DynamoDB();

exports.handler = async (event) => {
    for (const record of event.Records) {
        const id = record.body;
        console.log(id);

        const params = {
            TableName: process.env.TABLE_NAME,
            Item: {
                "id": {
                    N: id
                }
            }
        }

        await dynamodb.putItem(params).promise();
    }

    return;
}

package.json

{
  "name": "serverless-stack",
  "version": "0.1.0",
  "bin": {
    "serverless-stack": "bin/serverless-stack.js"
  },
  "scripts": {
    "build": "tsc",
    "watch": "tsc -w",
    "test": "jest",
    "cdk": "cdk"
  },
  "devDependencies": {
    "@aws-cdk/assert": "1.59.0",
    "@types/jest": "^26.0.4",
    "@types/node": "10.17.27",
    "jest": "^26.0.4",
    "ts-jest": "^26.1.3",
    "aws-cdk": "1.59.0",
    "ts-node": "^8.1.0",
    "typescript": "~3.9.6"
  },
  "dependencies": {
    "@aws-cdk/core": "1.59.0",
    "source-map-support": "^0.5.16",
    "@aws-cdk/aws-sqs": "^1.59.0",
    "@aws-cdk/aws-dynamodb": "^1.59.0",
    "@aws-cdk/aws-apigateway": "^1.59.0",
    "@aws-cdk/aws-lambda-event-sources": "^1.59.0",
    "@aws-cdk/aws-lambda": "^1.59.0",
    "@aws-cdk/aws-iam": "^1.59.0"
  }
}

serverless-stack.ts

#!/usr/bin/env node
import 'source-map-support/register';
import * as cdk from '@aws-cdk/core';
import { ServerlessStackStack } from '../lib/serverless-stack-stack';

const app = new cdk.App();
new ServerlessStackStack(app, 'ServerlessStackStack');