Infrastructure as Code (IaC) is changing the ways cloud resources are designed and deployed. AWS CDK extends the advantages in using IaC through support for familiar programming languages like TypeScript, Python, and Java, offering better integration with their existing developer workflows.

The following article tries to review the essential concepts, benefits, and best practices to be followed while using AWS CDK to design reliable and scalable infrastructure.

Why Choose AWS CDK?

AWS CDK abstracts low-level CloudFormation templates into high-level constructs, making the infrastructure code:
• Declarative: By using structures to declare resources in an ordered hierarchy.
• Reusable: With constructs, you can create reusable patterns for consistent infrastructure.
• Developer-Friendly: Write infrastructure code in TypeScript, Python, or Java while leveraging IDE features like auto-completion and linting.

Principal Features:

• Support for multiple languages.
• Full integration with AWS services.
• Writing libraries for common patterns of infrastructure.

Getting Started

Prerequisites

• AWS CLI configured with credentials.
• Node.js installed.
• AWS CDK installed globally via npm:

npm install -g aws-cdk

Initializing a New CDK Project

Run the following command to bootstrap your project:

cdk init app --language typescript

This generates a basic project structure with an example stack.

Designing Scalable Infrastructure

Here’s an example of defining a serverless stack using AWS Lambda and API Gateway in TypeScript:

import * as cdk from 'aws-cdk-lib';
import { Stack, StackProps } from 'aws-cdk-lib';
import * as lambda from 'aws-cdk-lib/aws-lambda';
import * as apigateway from 'aws-cdk-lib/aws-apigateway';

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

   // Lambda Function
    const helloFunction = new lambda.Function(this, 'HelloFunction', {
      runtime: lambda.Runtime.NODEJS_16_X,
      code: lambda.Code.fromAsset('lambda'),
      handler: 'index.handler',
    });

     // API Gateway
    new apigateway.LambdaRestApi(this, 'HelloApi', {
      handler: helloFunction,
    });
  }
}

Key Takeaways from This Example:

• Scalability: API Gateway and Lambda automatically scale based on demand.
• Modularity: Logical grouping of resources simplifies maintenance.

Best Practices for CDK

1. Use Constructs Effectively

Leverage higher-level constructs (L2 or L3) from the AWS Construct Library for simplicity.
Example: Use aws-cdk-lib/aws-s3-deployment for S3 uploads instead of writing custom scripts.

2. Keep Constructs Modular

Create separate files or modules for different constructs. This improves reusability:

export class StorageConstruct extends cdk.Construct {
  constructor(scope: cdk.Construct, id: string) {
    super(scope, id);

    const bucket = new s3.Bucket(this, 'MyBucket', {
      versioned: true,
    });
  }
}

3. Leverage Context and Parameters

Use CDK context and parameters for environment-specific configurations:

cdk deploy --context env=production

4. Monitor and Optimize Costs

• Use AWS Budgets and CloudWatch for tracking expenses.
• Ensure cost-efficient services by setting lifecycle policies or reserved capacity.

5. Test Your Infrastructure

Tools like AWS CDK Assertions allow you to test your stacks programmatically:

import { Template } from 'aws-cdk-lib/assertions';
const template = Template.fromStack(myStack);
template.hasResource('AWS::S3::Bucket', {});

Deploying and Managing Infrastructure

1. Synthesizing CloudFormation Templates

• Generate a CloudFormation stack from your code:

cdk synth

2. Deploying Your Stack
Push the stack to AWS:

cdk deploy

3. Destroying Stacks
Clean up resources when no longer needed:

cdk destroy

Conclusion

AWS CDK is a powerful tool for building scalable and maintainable infrastructure. By following best practices and leveraging its features, you can streamline development, enforce consistency, and prepare your infrastructure to handle growth.

Ready to try it out? Start building your scalable applications with AWS CDK today!