AWS CloudFormation & CDK — Infrastructure as Code

AWS offers two native IaC tools: CloudFormation (declarative YAML/JSON templates) and the AWS CDK (define infrastructure in your programming language of choice).

In Azure terms: CloudFormation ≈ ARM Templates, CDK ≈ Bicep / Pulumi

AWS CloudFormation

CloudFormation lets you model your entire AWS infrastructure as a template and deploy it as a stack.

Template Structure (YAML)

AWSTemplateFormatVersion: '2010-09-09'
Description: 'Simple web app stack'

Parameters:
  EnvironmentName:
    Type: String
    Default: dev
    AllowedValues: [dev, staging, prod]

Resources:
  # S3 Bucket
  AppBucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: !Sub 'my-app-${EnvironmentName}-${AWS::AccountId}'
      VersioningConfiguration:
        Status: Enabled

  # EC2 Instance
  WebServer:
    Type: AWS::EC2::Instance
    Properties:
      InstanceType: t3.micro
      ImageId: ami-0abcdef1234567890
      Tags:
        - Key: Environment
          Value: !Ref EnvironmentName

Outputs:
  BucketName:
    Value: !Ref AppBucket
    Export:
      Name: !Sub '${AWS::StackName}-BucketName'

Key CloudFormation Concepts

Concept	Description
Stack	A deployed instance of a template — create, update, or delete as a unit
Change Set	Preview changes to a stack before applying them
Stack Set	Deploy the same stack across multiple accounts and regions
Drift Detection	Detect manual changes to resources not reflected in the template
Nested Stacks	Reference other CloudFormation stacks for modular design
Outputs & Exports	Share values between stacks
`!Ref`	Reference a parameter or resource logical ID
`!Sub`	String substitution with variable interpolation
`!GetAtt`	Get an attribute of a resource (e.g., bucket ARN)

CloudFormation CLI

# Create a stack
aws cloudformation create-stack \
  --stack-name my-stack \
  --template-body file://template.yaml \
  --parameters ParameterKey=EnvironmentName,ParameterValue=dev \
  --capabilities CAPABILITY_IAM

# Update a stack
aws cloudformation update-stack \
  --stack-name my-stack \
  --template-body file://template.yaml

# Create a change set (preview changes)
aws cloudformation create-change-set \
  --stack-name my-stack \
  --change-set-name my-changes \
  --template-body file://template.yaml

# Delete a stack
aws cloudformation delete-stack --stack-name my-stack

# Describe stack resources
aws cloudformation describe-stack-resources --stack-name my-stack

AWS CDK — Cloud Development Kit

The AWS CDK lets you define infrastructure using TypeScript, Python, Java, C#, or Go — with the full power of a programming language (loops, conditionals, abstractions).

CDK synthesizes your code into a CloudFormation template and then deploys it.

CDK Concepts

Concept	Description
App	Root of the CDK application
Stack	CloudFormation stack — unit of deployment
Construct	A reusable cloud component (L1, L2, or L3)
L1 Constructs	Direct CloudFormation resource wrappers (`CfnBucket`)
L2 Constructs	Higher-level, opinionated abstractions (`Bucket`, `Function`)
L3 Constructs	Patterns — multiple L2s pre-wired together

CDK Example (TypeScript)

import * as cdk from 'aws-cdk-lib';
import * as s3 from 'aws-cdk-lib/aws-s3';
import * as lambda from 'aws-cdk-lib/aws-lambda';
import * as s3n from 'aws-cdk-lib/aws-s3-notifications';

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

    // S3 bucket
    const bucket = new s3.Bucket(this, 'MyBucket', {
      versioned: true,
      encryption: s3.BucketEncryption.S3_MANAGED,
      removalPolicy: cdk.RemovalPolicy.DESTROY,
    });

    // Lambda function triggered by S3 uploads
    const fn = new lambda.Function(this, 'ProcessUpload', {
      runtime: lambda.Runtime.PYTHON_3_12,
      code: lambda.Code.fromAsset('lambda'),
      handler: 'handler.main',
      environment: {
        BUCKET_NAME: bucket.bucketName,
      },
    });

    // Grant Lambda read access to the bucket
    bucket.grantRead(fn);

    // Trigger Lambda on S3 object creation
    bucket.addEventNotification(
      s3.EventType.OBJECT_CREATED,
      new s3n.LambdaDestination(fn)
    );
  }
}

CDK CLI Commands

# Install CDK
npm install -g aws-cdk

# Initialize a new CDK project (TypeScript)
cdk init app --language typescript

# Synthesize CloudFormation template
cdk synth

# Compare deployed stack with local code
cdk diff

# Deploy
cdk deploy

# Destroy the stack
cdk destroy

CloudFormation vs CDK vs Terraform

Feature	CloudFormation	CDK	Terraform
Language	YAML / JSON	TypeScript, Python, Java, C#, Go	HCL
Learning curve	Medium	Low (if you know the language)	Medium
AWS-native	Yes	Yes (compiles to CFN)	No (multi-cloud)
State management	CloudFormation stack state	CloudFormation stack state	Terraform state file
Multi-cloud	No	No	Yes
Community	AWS-focused	AWS-focused	Massive, multi-cloud
IDEs / autocomplete	Limited	Excellent (TypeScript)	Good
Best for	Simple stacks, platform teams	Complex apps, developer-friendly	Multi-cloud, Terraform shops

Recommendation for Azure devs: CDK with TypeScript feels most like Bicep or Pulumi — familiar code-based approach rather than pure markup.

AWS CloudFormation & CDK — Infrastructure as Code

AWS CloudFormation & CDK — Infrastructure as Code