Introduction

AWS CloudFormation has long been the go-to Infrastructure-as-Code (IaC) tool for managing AWS resources. However, with the advent of the AWS Cloud Development Kit (AWS CDK), developers and DevOps teams are transitioning to a more flexible, programmatic approach to defining infrastructure. This guide outlines how to migrate existing AWS CloudFormation templates to AWS CDK efficiently.

Why Migrate from AWS CloudFormation to AWS CDK?

AWS CDK offers several advantages over AWS CloudFormation:

  • Improved Maintainability: Write infrastructure as code using TypeScript, Python, Java, or C#.
  • Code Reusability: Utilize loops, conditions, and object-oriented programming principles.
  • Faster Development: Reduce the need for verbose JSON/YAML templates.
  • Stronger Testing Capabilities: Implement unit and integration tests for infrastructure.

Steps to Migrate AWS CloudFormation Templates to AWS CDK

1. Install AWS CDK

Ensure that AWS CDK is installed on the system. Run the following command:

sh

npm install -g aws-cdk

Verify the installation with:

sh

cdk –version

2. Initialize a New AWS CDK Project

Navigate to the project directory and create a new AWS CDK application:

sh

cdk init app –language=typescript

Replace typescript with python, java, or csharp depending on the preferred programming language.

3. Import the Existing CloudFormation Template

Use the cdk import command or manually convert CloudFormation templates into AWS CDK constructs.

Example of importing an existing CloudFormation resource:

typescript

import * as cdk from ‘aws-cdk-lib’;

import * as s3 from ‘aws-cdk-lib/aws-s3’;

class MyStack extends cdk.Stack {

  constructor(scope: cdk.App, id: string, props?: cdk.StackProps) {

    super(scope, id, props);

    // Define an S3 bucket from an existing CloudFormation template

    new s3.Bucket(this, ‘MyBucket’, {

      versioned: true,

      removalPolicy: cdk.RemovalPolicy.RETAIN,

    });

  }

}

const app = new cdk.App();

new MyStack(app, ‘MyCDKStack’);

4. Translate CloudFormation Resources to CDK Constructs

Each CloudFormation resource should be mapped to an equivalent AWS CDK construct.

Example: Converting an S3 bucket from YAML-based CloudFormation to AWS CDK in TypeScript:

CloudFormation (YAML):

yaml

Resources:

  MyS3Bucket:

    Type: AWS::S3::Bucket

    Properties:

      VersioningConfiguration:

        Status: Enabled

AWS CDK (TypeScript):

typescript

new s3.Bucket(this, ‘MyS3Bucket’, {

  versioned: true

});

5. Test and Deploy the CDK Application

Before deployment, ensure the application is synthesized correctly:

sh

cdk synth

Deploy the stack using:

sh

cdk deploy

6. Validate Migration and Monitor Changes

  • Compare generated AWS CloudFormation stacks using cdk diff.
  • Ensure the migration aligns with security best practices.
  • Monitor AWS CloudFormation Stack changes in the AWS Management Console.

Conclusion

Migrating AWS CloudFormation templates to AWS CDK enhances scalability, maintainability, and efficiency. By following a structured approach, organizations can streamline their infrastructure management with modern Infrastructure-as-Code best practices.