Deploy a hello world Lambda function

Table of Content

Add function code for Lambda function

• Create a lambda directory in root of your CDK project.

• In the lambda directory, create a hello.mjs file with the following content:

  export async function handler(event) {
    console.log("request:", JSON.stringify(event, undefined, 2));
    return {
      statusCode: 200,
      headers: { "Content-Type": "text/plain" },
      body: `Hi, CDK! You've hit ${event.path}\n`,
    };
  }
  

Add CDK code for Lambda function

• Update the main stack at lib/cdk-workshop-stack.ts:

  import { Stack, StackProps } from "aws-cdk-lib";
  import { Construct } from "constructs";
  import { Code, Function, Runtime } from "aws-cdk-lib/aws-lambda";
  
  export class CdkWorkshopStack extends Stack {
    constructor(scope: Construct, id: string, props?: StackProps) {
      super(scope, id, props);
  
      const hello = new Function(this, "HelloHandler", {
        runtime: Runtime.NODEJS_22_X,
        code: Code.fromAsset("lambda"),
        handler: "hello.handler",
      });
    }
  }
  

  Your CDK stack now contains a HelloHandler Lambda function that:

  • use the code from lambda directory.
  • the file is hello.
  • the function name is handler.

[Optional] Run cdk diff to check the difference of your CDK stack

• Use cdk diff to compare the difference between the stack in your CDK app with the deployed CDK stack (in your AWS account)

  cdk diff
  

  

  • The IAM statement and resources in red will be deleted.

    

    

  • The IAM statement, IAM policy and resources in green will be created.

    

    

Run cdk deploy to deploy your CDK stack with the lambda function

• Run cdk deploy to deploy your CDK stack with the hello world lambda function.

  

• To confirm, type y and press Enter.

  

Verify Lambda function is deployed and test it

• Check the CdkWorkshopStack in CloudFormation Console to verify that HelloHandler and a HelloHandlerServiceRole is created.

  

• Click on the HelloHandler Physical Id to open the detail page of the Lambda function.

  

• Open the Test tab, click Test button to invoke your HelloHandler.

  

• Check the detail to verify HelloHandler is invoked succeeded.

  

• Now, you have used CDK to deploy

  • a Lambda function
  • a SQS queue
  • a SNS topic

• In the next step, you will deploy your list-users handler that interact with a DynamoDB.