How to Generate a CloudFormation Template in AWS CDK

Generating CloudFormation Templates in AWS CDK #

In order to generate a CloudFormation template in AWS CDK we have to use the cdk synth command.

The cdk synth command does a couple of things for us:

• it executes our CDK code, so we would get notified if we had any syntax, type or cdk validation errors
• it generates the CloudFormation equivalent of our CDK stack and stores it in the cdk.out directory

In order to demo the process, I'll create a small cdk application, that consists of a single S3 bucket:

Copied!
import * as s3 from '@aws-cdk/aws-s3';
import * as cdk from '@aws-cdk/core';

export class MyCdkStack extends cdk.Stack {
  constructor(scope: cdk.App, id: string, props: cdk.StackProps) {
    super(scope, id, props);

    // 👇 create our Bucket resource
    const s3Bucket = new s3.Bucket(this, 'avatars-bucket', {
      removalPolicy: cdk.RemovalPolicy.DESTROY,
    });
  }
}

const app = new cdk.App();

new MyCdkStack(app, 'my-cdk-stack', {
  stackName: 'my-cdk-stack',
  env: {
    region: process.env.CDK_DEFAULT_REGION,
    account: process.env.CDK_DEFAULT_ACCOUNT,
  },
});

In the code snippet:

1. We've defined our CDK stack and used the Bucket construct to create a bucket resource

2. We've instantiated our CDK stack in the scope of the CDK app

In order to generate the CloudFormation template equivalent of our CDK stack, I have to run the synth command:

Copied!
npx cdk synth

The command outputs the complete CloudFormation equivalent of our CDK stack, in our case the S3 bucket:

If we take a look at the cdk.out directory we can see that our CloudFormation template has been generated and is ready for deployment:

At this point we've generated the CloudFormation equivalent of our CDK stack and we're ready to deploy using the cdk deploy command.

Further Reading #

• AWS CDK Tutorial for Beginners - Step-by-Step Guide
• How does AWS CDK work
• What is an identifier (id) in AWS CDK
• CDK Constructs - Complete Guide
• What is a Token in AWS CDK
• How to use Context in AWS CDK
• How to use Parameters in AWS CDK