devops-exercises/topics/aws/exercises/sample_cdk/solution.md

Set up a CDK Project - Solution

Exercise

Initialize a CDK project and set up files required to build a CDK project.

Solution

Initialize a CDK project

1. Install CDK on your machine by running npm install -g aws-cdk.
2. Create a new directory named sample for your project and run cdk init app --language typescript to initialize a CDK project. You can choose language as csharp, fsharp, go, java, javascript, python or typescript.
3. You would see the following files created in your directory:
   1. cdk.json, tsconfig.json, package.json - These are configuration files that are used to define some global settings for your CDK project.
   2. bin/sample.ts - This is the entry point for your CDK project. This file is used to define the stack that you want to create.
   3. lib/sample-stack.ts - This is the main file that will contain the code for your CDK project.

Create a Sample lambda function

1. In lib/sample-stack.ts file, add the following code to create a lambda function:

import * as cdk from 'aws-cdk-lib';
import * as lambda from 'aws-cdk-lib/aws-lambda';
import { Construct } from 'constructs';

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

    const hello = new lambda.Function(this, 'SampleLambda', {
      runtime: lambda.Runtime.NODEJS_14_X,
      code: lambda.Code.fromInline('exports.handler = async () => "hello world";'),
      handler: 'index.handler'
    });
  }
}

This will create a sample lambda function that returns "hello world" when invoked.

Bootstrap the CDK project

Before you deploy your project. You need to bootstrap your project. This will create a CloudFormation stack that will be used to deploy your project. You can bootstrap your project by running cdk bootstrap.

Learn more about bootstrapping here.

Deploy the Project

1. Run npm install to install all the dependencies for your project whenever you make changes.
2. Run cdk synth to synthesize the CloudFormation template for your project. You will see a new file called cdk.out/CDKToolkit.template.json that contains the CloudFormation template for your project.
3. Run cdk diff to see the changes that will be made to your AWS account. You will see a new stack called SampleStack that will create a lambda function and all the changes associated with it.
4. Run cdk deploy to deploy your project. You should see a new stack called created in your AWS account under CloudFormation.
5. Go to Lambda console and you will see a new lambda function called SampleLambda created in your account.