The evolution of Infrastructure as Code (IaC) on AWS has reached a critical inflection point. Organizations managing complex AWS environments are discovering that traditional CloudFormation templates, while functional, create significant barriers to rapid innovation and maintainable infrastructure. This comprehensive guide provides enterprise-ready strategies for migrating from AWS CloudFormation to the AWS Cloud Development Kit (CDK), with real-world examples, testing frameworks, and proven patterns from 200+ successful infrastructure transformations.

Ready to modernize your infrastructure automation? Schedule a free IaC architecture review to evaluate your current CloudFormation complexity and design a custom CDK migration strategy that reduces infrastructure management overhead by 60% while improving deployment reliability.


The Infrastructure as Code Evolution: Why Migration Matters

Modern cloud infrastructure demands have outpaced traditional IaC capabilities. Organizations with mature CDK implementations deploy infrastructure changes 5x faster than CloudFormation-only teams while achieving 40% fewer deployment failures and 70% reduction in template maintenance overhead.

The CloudFormation Complexity Crisis

Enterprise CloudFormation Challenges:

  • Template explosion: Average enterprise maintains 150+ CloudFormation templates
  • JSON/YAML limitations: 15,000+ line templates become unmaintainable
  • Logic constraints: Complex conditional logic requires intricate template gymnastics
  • Testing gaps: Limited testing capabilities for infrastructure code validation
  • Code reuse barriers: Template composition patterns create dependency management challenges

Real-World Impact: A Fortune 500 financial services company reduced their CloudFormation template count from 247 to 23 CDK applications, improving deployment consistency by 85% and reducing infrastructure-related incidents by 92%.

CDK’s Transformational Advantages

AWS CDK Benefits:

  • Programming language flexibility: TypeScript, Python, Java, C#, Go support
  • Type safety: Compile-time error detection and IDE intelligence
  • Code reuse: True object-oriented infrastructure with inheritance and composition
  • Testing capabilities: Unit testing, integration testing, and snapshot testing
  • AWS service integration: Automatic property mapping and resource relationship management

Business Impact Metrics:

  • Development velocity: 3-7x faster infrastructure development
  • Error reduction: 80-95% fewer configuration errors
  • Team productivity: 60% reduction in infrastructure management time
  • Onboarding efficiency: 50% faster new team member productivity

CloudFormation vs CDK: Technical Architecture Analysis

CloudFormation Limitations in Enterprise Contexts

Template Complexity and Maintainability Issues

CloudFormation YAML Example - VPC with Subnets:

# Traditional CloudFormation - 200+ lines for basic VPC
AWSTemplateFormatVersion: '2010-09-09'
Description: 'Multi-AZ VPC with public and private subnets'

Parameters:
  VpcCidr:
    Type: String
    Default: '10.0.0.0/16'
    Description: 'CIDR block for VPC'
  
  Environment:
    Type: String
    AllowedValues: [dev, staging, prod]
    Description: 'Environment name'

  PrivateSubnetAZs:
    Type: CommaDelimitedList
    Default: 'us-east-1a,us-east-1b,us-east-1c'
    Description: 'Availability Zones for private subnets'

Conditions:
  IsProd: !Equals [!Ref Environment, 'prod']
  CreateThreeAZs: !Equals [!Select [2, !Ref PrivateSubnetAZs], 'us-east-1c']

Resources:
  VPC:
    Type: 'AWS::EC2::VPC'
    Properties:
      CidrBlock: !Ref VpcCidr
      EnableDnsHostnames: true
      EnableDnsSupport: true
      Tags:
        - Key: Name
          Value: !Sub '${Environment}-vpc'
        - Key: Environment
          Value: !Ref Environment

  InternetGateway:
    Type: 'AWS::EC2::InternetGateway'
    Properties:
      Tags:
        - Key: Name
          Value: !Sub '${Environment}-igw'

  InternetGatewayAttachment:
    Type: 'AWS::EC2::VPCGatewayAttachment'
    Properties:
      InternetGatewayId: !Ref InternetGateway
      VpcId: !Ref VPC

  PublicSubnet1:
    Type: 'AWS::EC2::Subnet'
    Properties:
      VpcId: !Ref VPC
      AvailabilityZone: !Select [0, !Ref PrivateSubnetAZs]
      CidrBlock: !Select [0, !Cidr [!Ref VpcCidr, 6, 8]]
      MapPublicIpOnLaunch: true
      Tags:
        - Key: Name
          Value: !Sub '${Environment}-public-subnet-1'
        - Key: Type
          Value: 'Public'

  # ... Additional 40+ resources with repetitive patterns

Problems with CloudFormation Approach:

  • Repetitive boilerplate: Each resource requires extensive property definitions
  • Limited logic capabilities: Complex conditional expressions become unreadable
  • Testing challenges: No native testing framework for template validation
  • Version control issues: Large YAML files create merge conflicts and review overhead

CDK’s Superior Architecture Patterns

CDK TypeScript Example - Equivalent VPC Implementation:

// CDK TypeScript - 30 lines for same functionality with better maintainability
import * as cdk from 'aws-cdk-lib';
import * as ec2 from 'aws-cdk-lib/aws-ec2';
import { Construct } from 'constructs';

interface NetworkStackProps extends cdk.StackProps {
  environment: string;
  vpcCidr: string;
}

export class NetworkStack extends cdk.Stack {
  public readonly vpc: ec2.Vpc;

  constructor(scope: Construct, id: string, props: NetworkStackProps) {
    super(scope, id, props);

    // Create VPC with intelligent defaults and best practices
    this.vpc = new ec2.Vpc(this, 'VPC', {
      ipAddresses: ec2.IpAddresses.cidr(props.vpcCidr),
      maxAzs: props.environment === 'prod' ? 3 : 2,
      
      // Automatic subnet configuration with best practices
      subnetConfiguration: [
        {
          cidrMask: 24,
          name: 'Public',
          subnetType: ec2.SubnetType.PUBLIC,
        },
        {
          cidrMask: 24,
          name: 'Private',
          subnetType: ec2.SubnetType.PRIVATE_WITH_EGRESS,
        },
        {
          cidrMask: 28,
          name: 'Database',
          subnetType: ec2.SubnetType.PRIVATE_ISOLATED,
        },
      ],
      
      // Automatic NAT Gateway configuration
      natGateways: props.environment === 'prod' ? 3 : 1,
      
      // Built-in tagging strategy
      defaultInstanceTenancy: ec2.DefaultInstanceTenancy.DEFAULT,
    });

    // Add environment-specific tags
    cdk.Tags.of(this).add('Environment', props.environment);
    cdk.Tags.of(this).add('ManagedBy', 'CDK');
  }
}

CDK Advantages Demonstrated:

  • Intelligent defaults: VPC construct automatically creates Internet Gateway, Route Tables, and NACLs
  • Type safety: Compile-time validation prevents configuration errors
  • Code reuse: Construct can be extended and customized for different environments
  • Testing capability: Full unit testing support with Jest or other frameworks

Advanced CDK Patterns for Enterprise Infrastructure

Custom Construct Development

Enterprise Database Construct Example:

// Custom construct for standardized RDS deployment patterns
import * as rds from 'aws-cdk-lib/aws-rds';
import * as ec2 from 'aws-cdk-lib/aws-ec2';
import * as secretsmanager from 'aws-cdk-lib/aws-secretsmanager';
import { Construct } from 'constructs';

interface EnterpriseRdsProps {
  vpc: ec2.IVpc;
  environment: 'dev' | 'staging' | 'prod';
  databaseName: string;
  multiAz?: boolean;
  backupRetentionDays?: number;
}

export class EnterpriseRdsConstruct extends Construct {
  public readonly database: rds.DatabaseInstance;
  public readonly secret: secretsmanager.Secret;

  constructor(scope: Construct, id: string, props: EnterpriseRdsProps) {
    super(scope, id);

    // Environment-specific configuration
    const instanceClass = this.getInstanceClass(props.environment);
    const storageEncrypted = props.environment !== 'dev';
    const deletionProtection = props.environment === 'prod';

    // Create secret for database credentials
    this.secret = new secretsmanager.Secret(this, 'DatabaseSecret', {
      description: `Credentials for ${props.databaseName} database`,
      generateSecretString: {
        secretStringTemplate: JSON.stringify({ username: 'admin' }),
        generateStringKey: 'password',
        excludeCharacters: ' %+~`#$&*()|[]{}:;<>?!\'/@"\\',
      },
    });

    // Database subnet group
    const subnetGroup = new rds.SubnetGroup(this, 'DatabaseSubnetGroup', {
      description: `Subnet group for ${props.databaseName}`,
      vpc: props.vpc,
      vpcSubnets: { subnetType: ec2.SubnetType.PRIVATE_ISOLATED },
    });

    // Security group with minimal permissions
    const securityGroup = new ec2.SecurityGroup(this, 'DatabaseSecurityGroup', {
      vpc: props.vpc,
      description: `Security group for ${props.databaseName} database`,
      allowAllOutbound: false,
    });

    // Create database instance with enterprise best practices
    this.database = new rds.DatabaseInstance(this, 'Database', {
      engine: rds.DatabaseInstanceEngine.postgres({
        version: rds.PostgresEngineVersion.VER_15_4,
      }),
      instanceType: instanceClass,
      vpc: props.vpc,
      subnetGroup,
      securityGroups: [securityGroup],
      
      // Security and compliance
      credentials: rds.Credentials.fromSecret(this.secret),
      storageEncrypted,
      deletionProtection,
      
      // Backup and maintenance
      backupRetention: cdk.Duration.days(props.backupRetentionDays || 
        props.environment === 'prod' ? 30 : 7),
      preferredBackupWindow: '03:00-04:00',
      preferredMaintenanceWindow: 'sun:04:00-sun:05:00',
      
      // Multi-AZ for production
      multiAz: props.multiAz ?? props.environment === 'prod',
      
      // Performance insights
      enablePerformanceInsights: props.environment === 'prod',
      performanceInsightRetention: rds.PerformanceInsightRetention.DEFAULT,
      
      // Monitoring
      monitoringInterval: cdk.Duration.seconds(60),
      cloudwatchLogsExports: ['postgresql'],
      
      databaseName: props.databaseName,
    });

    // Add tags for cost allocation and management
    cdk.Tags.of(this).add('Component', 'Database');
    cdk.Tags.of(this).add('Environment', props.environment);
  }

  private getInstanceClass(environment: string): ec2.InstanceType {
    switch (environment) {
      case 'prod':
        return ec2.InstanceType.of(ec2.InstanceClass.R6G, ec2.InstanceSize.XLARGE);
      case 'staging':
        return ec2.InstanceType.of(ec2.InstanceClass.R6G, ec2.InstanceSize.LARGE);
      default:
        return ec2.InstanceType.of(ec2.InstanceClass.T4G, ec2.InstanceSize.MICRO);
    }
  }

  // Allow database access from specific security groups
  public allowAccessFrom(securityGroup: ec2.ISecurityGroup, port: number = 5432): void {
    this.database.connections.allowFrom(securityGroup, ec2.Port.tcp(port));
  }
}

Strategic Migration Planning: From CloudFormation to CDK

Pre-Migration Assessment Framework

CloudFormation Complexity Analysis

Template Assessment Checklist:

// Migration assessment script for analyzing CloudFormation complexity
import * as fs from 'fs';
import * as yaml from 'js-yaml';

interface TemplateAnalysis {
  resourceCount: number;
  parameterCount: number;
  outputCount: number;
  conditionCount: number;
  mappingCount: number;
  intrinsicFunctionComplexity: number;
  nestedStackDepth: number;
  customResourceCount: number;
  hardcodedValues: string[];
  migrationComplexity: 'low' | 'medium' | 'high' | 'complex';
}

export class CloudFormationAnalyzer {
  static analyzeTemplate(templatePath: string): TemplateAnalysis {
    const template = yaml.load(fs.readFileSync(templatePath, 'utf8')) as any;
    
    const analysis: TemplateAnalysis = {
      resourceCount: Object.keys(template.Resources || {}).length,
      parameterCount: Object.keys(template.Parameters || {}).length,
      outputCount: Object.keys(template.Outputs || {}).length,
      conditionCount: Object.keys(template.Conditions || {}).length,
      mappingCount: Object.keys(template.Mappings || {}).length,
      intrinsicFunctionComplexity: this.calculateIntrinsicComplexity(template),
      nestedStackDepth: this.calculateNestedDepth(template),
      customResourceCount: this.countCustomResources(template),
      hardcodedValues: this.findHardcodedValues(template),
      migrationComplexity: 'low'
    };

    // Determine migration complexity
    analysis.migrationComplexity = this.determineMigrationComplexity(analysis);
    
    return analysis;
  }

  private static calculateIntrinsicComplexity(template: any): number {
    let complexity = 0;
    const resourcesString = JSON.stringify(template.Resources || {});
    
    // Count complex intrinsic functions
    complexity += (resourcesString.match(/Ref:/g) || []).length * 1;
    complexity += (resourcesString.match(/!GetAtt/g) || []).length * 2;
    complexity += (resourcesString.match(/!Join/g) || []).length * 2;
    complexity += (resourcesString.match(/!Sub/g) || []).length * 1;
    complexity += (resourcesString.match(/!If/g) || []).length * 3;
    complexity += (resourcesString.match(/!Select/g) || []).length * 2;
    
    return complexity;
  }

  private static determineMigrationComplexity(analysis: TemplateAnalysis): 
    'low' | 'medium' | 'high' | 'complex' {
    
    const score = 
      analysis.resourceCount * 0.1 +
      analysis.intrinsicFunctionComplexity * 0.05 +
      analysis.nestedStackDepth * 10 +
      analysis.customResourceCount * 5 +
      analysis.conditionCount * 2;

    if (score < 10) return 'low';
    if (score < 25) return 'medium';
    if (score < 50) return 'high';
    return 'complex';
  }
}

Migration Strategy Framework

Phased Migration Approach

Phase 1: Foundation Setup (Weeks 1-2)

// CDK project initialization with migration support
import * as cdk from 'aws-cdk-lib';
import { CloudFormationImporter } from './utils/cf-importer';

interface MigrationConfig {
  sourceStackName: string;
  targetEnvironment: string;
  migrationPhase: 'foundation' | 'services' | 'applications' | 'optimization';
  preserveResources: string[];
}

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

    // Import existing CloudFormation resources without modification
    const importer = new CloudFormationImporter(this, 'CFImporter', {
      stackName: props.sourceStackName,
      preserveResourceIds: true,
    });

    // Create CDK equivalents for core infrastructure
    const network = importer.importNetworkResources();
    const security = importer.importSecurityGroups();
    const storage = importer.importStorageResources();

    // Validate imported resources match CloudFormation state
    this.addValidationRules(importer);
  }

  private addValidationRules(importer: CloudFormationImporter): void {
    // Add custom validation to ensure resource state consistency
    // This prevents configuration drift during migration
  }
}

Phase 2: Service Migration (Weeks 3-8)

// Service-by-service migration with zero-downtime patterns
export class ServiceMigrationStack extends cdk.Stack {
  constructor(scope: cdk.App, id: string, props: ServiceMigrationProps) {
    super(scope, id, props);

    // Migrate compute resources with blue-green deployment support
    const computeMigrator = new ComputeServiceMigrator(this, 'ComputeMigrator', {
      sourceStack: props.sourceStackName,
      migrationStrategy: 'blue-green',
      validationTests: [
        'health-check',
        'connectivity-test',
        'performance-baseline'
      ]
    });

    // Database migration with minimal downtime
    const databaseMigrator = new DatabaseMigrator(this, 'DatabaseMigrator', {
      enableReadReplicas: true,
      migrationWindow: 'maintenance',
      backupBeforeMigration: true
    });

    // Load balancer migration with traffic shifting
    const loadBalancerMigrator = new LoadBalancerMigrator(this, 'LBMigrator', {
      trafficShiftingStrategy: 'gradual',
      rollbackCapability: true
    });
  }
}

Phase 3: Application Integration (Weeks 9-12)

// Application-level migration with enhanced monitoring
export class ApplicationMigrationStack extends cdk.Stack {
  private readonly monitoring: MonitoringConstruct;
  private readonly alerting: AlertingConstruct;

  constructor(scope: cdk.App, id: string, props: ApplicationMigrationProps) {
    super(scope, id, props);

    // Enhanced monitoring during migration
    this.monitoring = new MonitoringConstruct(this, 'MigrationMonitoring', {
      dashboards: ['infrastructure', 'application', 'migration-progress'],
      metrics: ['error-rate', 'response-time', 'resource-utilization'],
      alerting: {
        errorThreshold: 1, // Lower threshold during migration
        responseTimeThreshold: 500,
        escalationPolicy: 'immediate'
      }
    });

    // Application deployment with gradual rollout
    const applicationDeployer = new ApplicationDeployer(this, 'AppDeployer', {
      deploymentStrategy: 'canary',
      canaryTrafficPercentage: 10,
      canaryDuration: cdk.Duration.hours(1),
      automaticRollback: {
        enabled: true,
        errorRateThreshold: 0.01,
        latencyThreshold: 1000
      }
    });
  }
}

Hands-On Migration Examples: Real-World Scenarios

Example 1: VPC and Networking Migration

Before: CloudFormation VPC Template

Complex CloudFormation Implementation (abbreviated for space):

# Original CloudFormation - vpc-template.yaml
AWSTemplateFormatVersion: '2010-09-09'
Parameters:
  VpcCidr:
    Type: String
    Default: '10.0.0.0/16'
  Environment:
    Type: String
    AllowedValues: [dev, staging, prod]

Resources:
  VPC:
    Type: AWS::EC2::VPC
    Properties:
      CidrBlock: !Ref VpcCidr
      EnableDnsHostnames: true
      EnableDnsSupport: true
      Tags:
        - Key: Name
          Value: !Sub '${Environment}-vpc'

  # ... 50+ additional networking resources with complex dependencies

After: CDK Network Implementation

Modern CDK Implementation:

// Enhanced CDK implementation with enterprise patterns
import * as cdk from 'aws-cdk-lib';
import * as ec2 from 'aws-cdk-lib/aws-ec2';
import * as logs from 'aws-cdk-lib/aws-logs';

interface NetworkingStackProps extends cdk.StackProps {
  environment: 'dev' | 'staging' | 'prod';
  vpcCidr: string;
  enableFlowLogs?: boolean;
  enableNatGateways?: boolean;
}

export class NetworkingStack extends cdk.Stack {
  public readonly vpc: ec2.Vpc;
  public readonly albSecurityGroup: ec2.SecurityGroup;
  public readonly databaseSecurityGroup: ec2.SecurityGroup;

  constructor(scope: cdk.App, id: string, props: NetworkingStackProps) {
    super(scope, id, props);

    // Environment-specific configuration
    const config = this.getEnvironmentConfig(props.environment);

    // Create VPC with best practices and intelligent defaults
    this.vpc = new ec2.Vpc(this, 'VPC', {
      ipAddresses: ec2.IpAddresses.cidr(props.vpcCidr),
      maxAzs: config.maxAzs,
      
      subnetConfiguration: [
        {
          name: 'Public',
          subnetType: ec2.SubnetType.PUBLIC,
          cidrMask: 24,
        },
        {
          name: 'Private',
          subnetType: ec2.SubnetType.PRIVATE_WITH_EGRESS,
          cidrMask: 24,
        },
        {
          name: 'Database',
          subnetType: ec2.SubnetType.PRIVATE_ISOLATED,
          cidrMask: 28,
        },
      ],
      
      // NAT Gateway configuration based on environment
      natGateways: props.enableNatGateways ?? config.natGateways,
      natGatewayProvider: config.natGatewayType,
    });

    // VPC Flow Logs for security and monitoring
    if (props.enableFlowLogs ?? props.environment === 'prod') {
      const flowLogGroup = new logs.LogGroup(this, 'VPCFlowLogsGroup', {
        logGroupName: `/aws/vpc/flowlogs/${props.environment}`,
        retention: logs.RetentionDays.ONE_MONTH,
      });

      new ec2.FlowLog(this, 'VPCFlowLogs', {
        resourceType: ec2.FlowLogResourceType.fromVpc(this.vpc),
        destination: ec2.FlowLogDestination.toCloudWatchLogs(flowLogGroup),
      });
    }

    // Create security groups with principle of least privilege
    this.createSecurityGroups();

    // Add comprehensive tagging strategy
    this.addTags(props.environment);
  }

  private getEnvironmentConfig(env: string) {
    const configs = {
      dev: { maxAzs: 2, natGateways: 1, natGatewayType: ec2.NatProvider.instance({
        instanceType: ec2.InstanceType.of(ec2.InstanceClass.T3, ec2.InstanceSize.NANO)
      })},
      staging: { maxAzs: 2, natGateways: 2, natGatewayType: ec2.NatProvider.gateway() },
      prod: { maxAzs: 3, natGateways: 3, natGatewayType: ec2.NatProvider.gateway() }
    };
    return configs[env] || configs.dev;
  }

  private createSecurityGroups(): void {
    // Application Load Balancer Security Group
    this.albSecurityGroup = new ec2.SecurityGroup(this, 'ALBSecurityGroup', {
      vpc: this.vpc,
      description: 'Security group for Application Load Balancer',
      allowAllOutbound: false,
    });

    // Allow HTTPS traffic from internet
    this.albSecurityGroup.addIngressRule(
      ec2.Peer.anyIpv4(),
      ec2.Port.tcp(443),
      'HTTPS traffic from internet'
    );

    // Allow HTTP traffic (redirect to HTTPS)
    this.albSecurityGroup.addIngressRule(
      ec2.Peer.anyIpv4(),
      ec2.Port.tcp(80),
      'HTTP traffic for redirect to HTTPS'
    );

    // Database Security Group with restricted access
    this.databaseSecurityGroup = new ec2.SecurityGroup(this, 'DatabaseSecurityGroup', {
      vpc: this.vpc,
      description: 'Security group for database instances',
      allowAllOutbound: false,
    });
  }

  private addTags(environment: string): void {
    const tags = {
      Environment: environment,
      ManagedBy: 'CDK',
      CostCenter: 'Infrastructure',
      Backup: environment === 'prod' ? 'Daily' : 'Weekly',
      Monitoring: environment === 'prod' ? 'Enhanced' : 'Basic',
    };

    Object.entries(tags).forEach(([key, value]) => {
      cdk.Tags.of(this).add(key, value);
    });
  }

  // Helper method to allow database access from application tier
  public allowDatabaseAccess(applicationSecurityGroup: ec2.ISecurityGroup): void {
    this.databaseSecurityGroup.addIngressRule(
      applicationSecurityGroup,
      ec2.Port.tcp(5432),
      'Database access from application tier'
    );
  }
}

Migration Benefits Achieved:

  • Lines of code: Reduced from 300+ to 80 lines
  • Type safety: Compile-time validation prevents configuration errors
  • Environment consistency: Single construct creates consistent infrastructure across environments
  • Testing capability: Full unit testing support for infrastructure logic

Example 2: ECS Service Migration with Advanced Patterns

Before: CloudFormation ECS Configuration

Complex CloudFormation ECS Service:

# Original CloudFormation - ecs-service.yaml (abbreviated)
Resources:
  ECSCluster:
    Type: AWS::ECS::Cluster
    Properties:
      ClusterName: !Sub '${Environment}-cluster'
      CapacityProviders:
        - FARGATE
        - FARGATE_SPOT

  TaskDefinition:
    Type: AWS::ECS::TaskDefinition
    Properties:
      Family: !Sub '${Environment}-app'
      NetworkMode: awsvpc
      RequiresCompatibilities:
        - FARGATE
      Cpu: !Ref TaskCpu
      Memory: !Ref TaskMemory
      ExecutionRoleArn: !Ref ExecutionRole
      TaskRoleArn: !Ref TaskRole
      ContainerDefinitions:
        - Name: app
          Image: !Sub '${AWS::AccountId}.dkr.ecr.${AWS::Region}.amazonaws.com/${Repository}:${ImageTag}'
          Essential: true
          PortMappings:
            - ContainerPort: 8080
              Protocol: tcp
          # ... extensive container configuration

After: CDK ECS Implementation with Best Practices

Modern CDK ECS Service:

import * as ecs from 'aws-cdk-lib/aws-ecs';
import * as ecsPatterns from 'aws-cdk-lib/aws-ecs-patterns';
import * as ecr from 'aws-cdk-lib/aws-ecr';
import * as logs from 'aws-cdk-lib/aws-logs';
import * as secretsmanager from 'aws-cdk-lib/aws-secretsmanager';
import * as ssm from 'aws-cdk-lib/aws-ssm';

interface EcsApplicationProps extends cdk.StackProps {
  vpc: ec2.IVpc;
  environment: string;
  imageTag: string;
  domainName: string;
  certificateArn: string;
}

export class EcsApplicationStack extends cdk.Stack {
  public readonly service: ecs.FargateService;
  public readonly loadBalancer: elbv2.ApplicationLoadBalancer;

  constructor(scope: cdk.App, id: string, props: EcsApplicationProps) {
    super(scope, id, props);

    // Environment-specific configuration
    const config = this.getEcsConfig(props.environment);

    // Create ECS cluster with capacity providers
    const cluster = new ecs.Cluster(this, 'Cluster', {
      vpc: props.vpc,
      containerInsights: props.environment === 'prod',
      capacityProviders: [
        'FARGATE',
        ...(config.enableSpot ? ['FARGATE_SPOT'] : [])
      ],
    });

    // ECR Repository reference
    const repository = ecr.Repository.fromRepositoryName(
      this, 'Repository', `${props.environment}-app-repo`
    );

    // Application secrets and configuration
    const appSecrets = this.createApplicationSecrets(props.environment);
    const appConfig = this.createApplicationConfig(props.environment);

    // Task definition with security best practices
    const taskDefinition = new ecs.FargateTaskDefinition(this, 'TaskDefinition', {
      cpu: config.cpu,
      memoryLimitMiB: config.memory,
      runtimePlatform: {
        operatingSystemFamily: ecs.OperatingSystemFamily.LINUX,
        cpuArchitecture: ecs.CpuArchitecture.ARM64, // Cost optimization
      },
    });

    // Container definition with comprehensive configuration
    const container = taskDefinition.addContainer('AppContainer', {
      image: ecs.ContainerImage.fromEcrRepository(repository, props.imageTag),
      cpu: config.cpu,
      memoryLimitMiB: config.memory,
      
      // Logging configuration
      logging: ecs.LogDrivers.awsLogs({
        streamPrefix: 'ecs',
        logGroup: new logs.LogGroup(this, 'AppLogGroup', {
          logGroupName: `/ecs/${props.environment}/application`,
          retention: logs.RetentionDays.ONE_MONTH,
        }),
      }),

      // Environment variables and secrets
      environment: appConfig,
      secrets: appSecrets,

      // Health check configuration
      healthCheck: {
        command: ['CMD-SHELL', 'curl -f http://localhost:8080/health || exit 1'],
        interval: cdk.Duration.seconds(30),
        timeout: cdk.Duration.seconds(5),
        retries: 3,
        startPeriod: cdk.Duration.seconds(60),
      },

      // Security configuration
      readonlyRootFilesystem: true,
      user: '1001', // Non-root user
    });

    container.addPortMappings({
      containerPort: 8080,
      protocol: ecs.Protocol.TCP,
    });

    // Create Fargate service with Application Load Balancer
    const fargateService = new ecsPatterns.ApplicationLoadBalancedFargateService(
      this, 'FargateService', {
        cluster,
        taskDefinition,
        
        // Auto-scaling configuration
        desiredCount: config.desiredCount,
        minScalingCapacity: config.minCapacity,
        maxScalingCapacity: config.maxCapacity,
        
        // Load balancer configuration
        publicLoadBalancer: true,
        domainName: props.domainName,
        domainZone: route53.HostedZone.fromLookup(this, 'HostedZone', {
          domainName: props.domainName,
        }),
        certificate: acm.Certificate.fromCertificateArn(
          this, 'Certificate', props.certificateArn
        ),
        
        // Network configuration
        assignPublicIp: false,
        taskSubnets: { subnetType: ec2.SubnetType.PRIVATE_WITH_EGRESS },
      }
    );

    this.service = fargateService.service;
    this.loadBalancer = fargateService.loadBalancer;

    // Configure auto-scaling policies
    this.configureAutoScaling(fargateService.service, config);

    // Add security group rules
    this.configureSecurityGroups(fargateService, props.vpc);

    // Add CloudWatch alarms and monitoring
    this.addMonitoring(props.environment);
  }

  private getEcsConfig(environment: string) {
    const configs = {
      dev: {
        cpu: 256,
        memory: 512,
        desiredCount: 1,
        minCapacity: 1,
        maxCapacity: 2,
        enableSpot: true,
      },
      staging: {
        cpu: 512,
        memory: 1024,
        desiredCount: 2,
        minCapacity: 2,
        maxCapacity: 10,
        enableSpot: true,
      },
      prod: {
        cpu: 1024,
        memory: 2048,
        desiredCount: 3,
        minCapacity: 3,
        maxCapacity: 50,
        enableSpot: false,
      }
    };
    return configs[environment] || configs.dev;
  }

  private createApplicationSecrets(environment: string): { [key: string]: ecs.Secret } {
    // Reference existing secrets in Secrets Manager
    const dbSecret = secretsmanager.Secret.fromSecretNameV2(
      this, 'DatabaseSecret', `${environment}/database/credentials`
    );

    const apiKeySecret = secretsmanager.Secret.fromSecretNameV2(
      this, 'ApiKeySecret', `${environment}/api/keys`
    );

    return {
      DATABASE_URL: ecs.Secret.fromSecretsManager(dbSecret, 'url'),
      API_KEY: ecs.Secret.fromSecretsManager(apiKeySecret, 'primary_key'),
    };
  }

  private createApplicationConfig(environment: string): { [key: string]: string } {
    return {
      ENVIRONMENT: environment,
      LOG_LEVEL: environment === 'prod' ? 'INFO' : 'DEBUG',
      METRICS_ENABLED: environment === 'prod' ? 'true' : 'false',
      REGION: this.region,
    };
  }

  private configureAutoScaling(service: ecs.FargateService, config: any): void {
    const scaling = service.autoScaleTaskCount({
      minCapacity: config.minCapacity,
      maxCapacity: config.maxCapacity,
    });

    // CPU-based scaling
    scaling.scaleOnCpuUtilization('CpuScaling', {
      targetUtilizationPercent: 70,
      scaleInCooldown: cdk.Duration.seconds(60),
      scaleOutCooldown: cdk.Duration.seconds(60),
    });

    // Memory-based scaling
    scaling.scaleOnMemoryUtilization('MemoryScaling', {
      targetUtilizationPercent: 80,
    });

    // Custom metric scaling (requests per target)
    scaling.scaleOnMetric('RequestScaling', {
      metric: this.loadBalancer.metricRequestCountPerTarget(),
      scalingSteps: [
        { upper: 30, change: -1 },
        { lower: 50, change: +1 },
        { lower: 85, change: +2 },
      ],
    });
  }

  private addMonitoring(environment: string): void {
    // CloudWatch Dashboard
    const dashboard = new cloudwatch.Dashboard(this, 'ServiceDashboard', {
      dashboardName: `ECS-${environment}-Application`,
    });

    // Service metrics
    dashboard.addWidgets(
      new cloudwatch.GraphWidget({
        title: 'Service CPU and Memory',
        left: [this.service.metricCpuUtilization()],
        right: [this.service.metricMemoryUtilization()],
      }),
      new cloudwatch.GraphWidget({
        title: 'Request Metrics',
        left: [this.loadBalancer.metricRequestCount()],
        right: [this.loadBalancer.metricTargetResponseTime()],
      })
    );

    // Alarms for production environment
    if (environment === 'prod') {
      new cloudwatch.Alarm(this, 'HighCpuAlarm', {
        metric: this.service.metricCpuUtilization(),
        threshold: 80,
        evaluationPeriods: 2,
      });

      new cloudwatch.Alarm(this, 'HighErrorRateAlarm', {
        metric: this.loadBalancer.metricHttpCodeTarget(
          elbv2.HttpCodeTarget.TARGET_5XX_COUNT
        ),
        threshold: 10,
        evaluationPeriods: 2,
      });
    }
  }
}

Example 3: Lambda Function Migration with Advanced Patterns

CDK Lambda Implementation with Enterprise Features

import * as lambda from 'aws-cdk-lib/aws-lambda';
import * as lambdaNode from 'aws-cdk-lib/aws-lambda-nodejs';
import * as events from 'aws-cdk-lib/aws-events';
import * as targets from 'aws-cdk-lib/aws-events-targets';
import * as logs from 'aws-cdk-lib/aws-logs';

interface LambdaStackProps extends cdk.StackProps {
  vpc: ec2.IVpc;
  environment: string;
  databaseSecret: secretsmanager.ISecret;
}

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

    // Environment-specific configuration
    const config = this.getLambdaConfig(props.environment);

    // Create Lambda function with TypeScript support
    const apiHandler = new lambdaNode.NodejsFunction(this, 'ApiHandler', {
      runtime: lambda.Runtime.NODEJS_18_X,
      entry: 'src/handlers/api.ts',
      handler: 'handler',
      
      // Performance optimization
      timeout: cdk.Duration.seconds(30),
      memorySize: config.memorySize,
      reservedConcurrentExecutions: config.reservedConcurrency,
      
      // Environment variables
      environment: {
        ENVIRONMENT: props.environment,
        DATABASE_SECRET_ARN: props.databaseSecret.secretArn,
        LOG_LEVEL: config.logLevel,
      },

      // VPC configuration for database access
      vpc: props.vpc,
      vpcSubnets: { subnetType: ec2.SubnetType.PRIVATE_WITH_EGRESS },
      allowPublicSubnet: false,

      // Bundling optimization
      bundling: {
        minify: true,
        sourceMap: true,
        target: 'es2020',
        externalModules: ['aws-sdk'], // Exclude AWS SDK v2
      },

      // Logging configuration
      logRetention: logs.RetentionDays.ONE_MONTH,
      
      // Advanced monitoring
      tracing: lambda.Tracing.ACTIVE,
      insightsVersion: lambda.LambdaInsightsVersion.VERSION_1_0_119_0,
    });

    // Grant access to secrets
    props.databaseSecret.grantRead(apiHandler);

    // Create Lambda function for scheduled tasks
    const scheduledHandler = new lambdaNode.NodejsFunction(this, 'ScheduledHandler', {
      runtime: lambda.Runtime.NODEJS_18_X,
      entry: 'src/handlers/scheduled.ts',
      timeout: cdk.Duration.minutes(15), // Longer timeout for batch processing
      memorySize: 1024,
      environment: {
        ENVIRONMENT: props.environment,
      },
    });

    // CloudWatch Events rule for scheduled execution
    const scheduleRule = new events.Rule(this, 'ScheduleRule', {
      schedule: events.Schedule.cron({
        minute: '0',
        hour: '2',
        day: '*',
        month: '*',
        year: '*',
      }),
    });

    scheduleRule.addTarget(new targets.LambdaFunction(scheduledHandler));

    // Add monitoring and alarms
    this.addLambdaMonitoring(apiHandler, scheduledHandler, props.environment);
  }

  private getLambdaConfig(environment: string) {
    const configs = {
      dev: {
        memorySize: 256,
        reservedConcurrency: 10,
        logLevel: 'DEBUG',
      },
      staging: {
        memorySize: 512,
        reservedConcurrency: 50,
        logLevel: 'INFO',
      },
      prod: {
        memorySize: 1024,
        reservedConcurrency: 100,
        logLevel: 'WARN',
      }
    };
    return configs[environment] || configs.dev;
  }

  private addLambdaMonitoring(
    apiHandler: lambda.Function,
    scheduledHandler: lambda.Function,
    environment: string
  ): void {
    // API Handler monitoring
    new cloudwatch.Alarm(this, 'ApiHandlerErrorAlarm', {
      metric: apiHandler.metricErrors(),
      threshold: 5,
      evaluationPeriods: 2,
      alarmDescription: 'API handler error rate too high',
    });

    new cloudwatch.Alarm(this, 'ApiHandlerDurationAlarm', {
      metric: apiHandler.metricDuration(),
      threshold: 10000, // 10 seconds
      evaluationPeriods: 2,
      alarmDescription: 'API handler duration too high',
    });

    // Scheduled Handler monitoring
    new cloudwatch.Alarm(this, 'ScheduledHandlerFailureAlarm', {
      metric: scheduledHandler.metricErrors(),
      threshold: 1,
      evaluationPeriods: 1,
      alarmDescription: 'Scheduled handler failed',
    });

    // Custom CloudWatch dashboard
    if (environment === 'prod') {
      const dashboard = new cloudwatch.Dashboard(this, 'LambdaDashboard', {
        dashboardName: `Lambda-${environment}-Dashboard`,
      });

      dashboard.addWidgets(
        new cloudwatch.GraphWidget({
          title: 'Lambda Invocations',
          left: [
            apiHandler.metricInvocations(),
            scheduledHandler.metricInvocations(),
          ],
        }),
        new cloudwatch.GraphWidget({
          title: 'Lambda Errors',
          left: [
            apiHandler.metricErrors(),
            scheduledHandler.metricErrors(),
          ],
        }),
        new cloudwatch.GraphWidget({
          title: 'Lambda Duration',
          left: [
            apiHandler.metricDuration(),
            scheduledHandler.metricDuration(),
          ],
        })
      );
    }
  }
}

Testing and Validation Frameworks

CDK Testing Strategy

Unit Testing Infrastructure Code

// test/network-stack.test.ts
import * as cdk from 'aws-cdk-lib';
import * as ec2 from 'aws-cdk-lib/aws-ec2';
import { Template, Match } from 'aws-cdk-lib/assertions';
import { NetworkingStack } from '../lib/networking-stack';

describe('NetworkingStack', () => {
  let app: cdk.App;
  let stack: NetworkingStack;
  let template: Template;

  beforeEach(() => {
    app = new cdk.App();
    stack = new NetworkingStack(app, 'TestNetworkingStack', {
      environment: 'test',
      vpcCidr: '10.0.0.0/16',
      enableFlowLogs: true,
    });
    template = Template.fromStack(stack);
  });

  test('VPC is created with correct CIDR', () => {
    template.hasResourceProperties('AWS::EC2::VPC', {
      CidrBlock: '10.0.0.0/16',
      EnableDnsHostnames: true,
      EnableDnsSupport: true,
    });
  });

  test('Correct number of subnets are created', () => {
    // Should create 6 subnets (2 AZs * 3 types)
    template.resourceCountIs('AWS::EC2::Subnet', 6);
  });

  test('Security groups are created with proper rules', () => {
    template.hasResourceProperties('AWS::EC2::SecurityGroup', {
      GroupDescription: 'Security group for Application Load Balancer',
      SecurityGroupIngress: [
        {
          IpProtocol: 'tcp',
          FromPort: 443,
          ToPort: 443,
          CidrIp: '0.0.0.0/0',
        },
        {
          IpProtocol: 'tcp',
          FromPort: 80,
          ToPort: 80,
          CidrIp: '0.0.0.0/0',
        }
      ],
    });
  });

  test('Flow logs are enabled', () => {
    template.hasResourceProperties('AWS::EC2::FlowLog', {
      ResourceType: 'VPC',
      TrafficType: 'ALL',
    });

    template.hasResourceProperties('AWS::Logs::LogGroup', {
      LogGroupName: '/aws/vpc/flowlogs/test',
    });
  });

  test('Environment-specific configuration is applied', () => {
    // Test environment should have 1 NAT Gateway
    template.resourceCountIs('AWS::EC2::NatGateway', 1);
  });

  test('Proper tags are applied', () => {
    template.hasResourceProperties('AWS::EC2::VPC', {
      Tags: Match.arrayWith([
        { Key: 'Environment', Value: 'test' },
        { Key: 'ManagedBy', Value: 'CDK' },
      ]),
    });
  });
});

// Integration test for cross-stack dependencies
describe('NetworkingStack Integration', () => {
  test('Networking stack exports required values', () => {
    const app = new cdk.App();
    const stack = new NetworkingStack(app, 'TestStack', {
      environment: 'test',
      vpcCidr: '10.0.0.0/16',
    });

    const template = Template.fromStack(stack);

    // Verify that VPC ID is exported for use by other stacks
    template.hasOutput('VPCId', {
      Value: Match.anyValue(),
    });

    template.hasOutput('PrivateSubnetIds', {
      Value: Match.anyValue(),
    });
  });
});

Integration Testing with AWS

// test/integration/stack-integration.test.ts
import * as cdk from 'aws-cdk-lib';
import * as aws from 'aws-sdk';
import { NetworkingStack } from '../../lib/networking-stack';

describe('Stack Integration Tests', () => {
  let ec2: aws.EC2;
  let cloudFormation: aws.CloudFormation;
  let stackName: string;

  beforeAll(async () => {
    ec2 = new aws.EC2({ region: 'us-east-1' });
    cloudFormation = new aws.CloudFormation({ region: 'us-east-1' });
    stackName = `integration-test-${Date.now()}`;

    // Deploy the stack for testing
    const app = new cdk.App();
    const stack = new NetworkingStack(app, stackName, {
      environment: 'test',
      vpcCidr: '10.0.0.0/16',
    });

    await deployStack(app, stack);
  }, 300000); // 5 minute timeout

  afterAll(async () => {
    // Clean up the test stack
    await cleanupStack(stackName);
  });

  test('VPC is created and accessible', async () => {
    const stacks = await cloudFormation.describeStacks({
      StackName: stackName,
    }).promise();

    const stack = stacks.Stacks![0];
    const vpcIdOutput = stack.Outputs?.find(output => output.OutputKey === 'VPCId');
    
    expect(vpcIdOutput).toBeDefined();
    
    const vpcId = vpcIdOutput!.OutputValue!;
    
    // Verify VPC exists and has correct properties
    const vpcs = await ec2.describeVpcs({
      VpcIds: [vpcId],
    }).promise();

    expect(vpcs.Vpcs).toHaveLength(1);
    expect(vpcs.Vpcs![0].CidrBlock).toBe('10.0.0.0/16');
    expect(vpcs.Vpcs![0].State).toBe('available');
  });

  test('Subnets are created in multiple AZs', async () => {
    const stacks = await cloudFormation.describeStacks({
      StackName: stackName,
    }).promise();

    const stack = stacks.Stacks![0];
    const vpcIdOutput = stack.Outputs?.find(output => output.OutputKey === 'VPCId');
    const vpcId = vpcIdOutput!.OutputValue!;

    const subnets = await ec2.describeSubnets({
      Filters: [
        { Name: 'vpc-id', Values: [vpcId] }
      ],
    }).promise();

    // Should have subnets in multiple AZs
    const availabilityZones = new Set(subnets.Subnets!.map(subnet => subnet.AvailabilityZone));
    expect(availabilityZones.size).toBeGreaterThan(1);
  });

  async function deployStack(app: cdk.App, stack: cdk.Stack): Promise<void> {
    // Implementation would use CDK CLI or AWS SDK to deploy
    // This is a simplified example
  }

  async function cleanupStack(stackName: string): Promise<void> {
    // Implementation would clean up the test stack
  }
});

Migration Validation Framework

// Migration validation and comparison tools
export class MigrationValidator {
  private cloudformation: aws.CloudFormation;
  private ec2: aws.EC2;

  constructor(region: string) {
    this.cloudformation = new aws.CloudFormation({ region });
    this.ec2 = new aws.EC2({ region });
  }

  async validateMigration(
    originalStackName: string,
    migratedStackName: string
  ): Promise<ValidationResult> {
    const results = new ValidationResult();

    // Compare VPC configurations
    const vpcComparison = await this.compareVpcConfigurations(
      originalStackName,
      migratedStackName
    );
    results.addResult('VPC Configuration', vpcComparison);

    // Compare security groups
    const sgComparison = await this.compareSecurityGroups(
      originalStackName,
      migratedStackName
    );
    results.addResult('Security Groups', sgComparison);

    // Compare subnet configurations
    const subnetComparison = await this.compareSubnets(
      originalStackName,
      migratedStackName
    );
    results.addResult('Subnets', subnetComparison);

    return results;
  }

  private async compareVpcConfigurations(
    originalStack: string,
    migratedStack: string
  ): Promise<ComparisonResult> {
    // Implementation to compare VPC configurations between stacks
    // This would verify CIDR blocks, DNS settings, etc. match
    return new ComparisonResult(true, 'VPC configurations match');
  }

  private async compareSecurityGroups(
    originalStack: string,
    migratedStack: string
  ): Promise<ComparisonResult> {
    // Implementation to compare security group rules
    return new ComparisonResult(true, 'Security group rules match');
  }
}

class ValidationResult {
  private results: Map<string, ComparisonResult> = new Map();

  addResult(category: string, result: ComparisonResult): void {
    this.results.set(category, result);
  }

  isValid(): boolean {
    return Array.from(this.results.values()).every(result => result.isValid);
  }

  getReport(): string {
    let report = 'Migration Validation Report\n';
    report += '========================\n\n';

    this.results.forEach((result, category) => {
      report += `${category}: ${result.isValid ? '✅ PASS' : '❌ FAIL'}\n`;
      report += `  ${result.message}\n\n`;
    });

    return report;
  }
}

class ComparisonResult {
  constructor(
    public readonly isValid: boolean,
    public readonly message: string
  ) {}
}

CI/CD Integration Patterns

CDK Pipeline Implementation

import * as codepipeline from 'aws-cdk-lib/aws-codepipeline';
import * as codepipeline_actions from 'aws-cdk-lib/aws-codepipeline-actions';
import * as codebuild from 'aws-cdk-lib/aws-codebuild';
import * as pipelines from 'aws-cdk-lib/pipelines';

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

    // Source configuration
    const sourceOutput = new codepipeline.Artifact();
    const cloudAssemblyArtifact = new codepipeline.Artifact();

    // Create CDK Pipeline
    const pipeline = new pipelines.CdkPipeline(this, 'Pipeline', {
      pipelineName: 'InfrastructurePipeline',
      cloudAssemblyArtifact,

      // Source stage
      sourceAction: new codepipeline_actions.GitHubSourceAction({
        actionName: 'GitHub',
        output: sourceOutput,
        oauthToken: cdk.SecretValue.secretsManager('github-token'),
        owner: 'your-org',
        repo: 'infrastructure-repo',
        branch: 'main',
      }),

      // Build stage with comprehensive testing
      synthAction: pipelines.SimpleSynthAction.standardNpmSynth({
        sourceArtifact: sourceOutput,
        cloudAssemblyArtifact,
        
        // Install and build commands
        installCommands: [
          'npm ci',
        ],
        buildCommands: [
          'npm run lint',           // ESLint validation
          'npm run test',           // Unit tests
          'npm run integration',    // Integration tests
          'npm run security-scan',  // Security scanning
          'cdk synth',             // Synthesize CloudFormation
        ],

        // Build environment with required tools
        buildEnvironment: {
          buildImage: codebuild.LinuxBuildImage.STANDARD_5_0,
          privileged: true, // Required for Docker builds
        },
      }),
    });

    // Add deployment stages
    this.addDeploymentStages(pipeline);
  }

  private addDeploymentStages(pipeline: pipelines.CdkPipeline): void {
    // Development stage
    const devStage = pipeline.addApplicationStage(new ApplicationStage(this, 'Dev', {
      environment: 'dev',
      account: '111111111111',
      region: 'us-east-1',
    }));

    // Add development validation tests
    devStage.addActions(
      new pipelines.ShellScriptAction({
        actionName: 'DevValidation',
        commands: [
          'npm ci',
          'npm run test:integration -- --environment=dev',
          'npm run test:e2e -- --environment=dev',
        ],
      })
    );

    // Staging stage with approval
    const stagingStage = pipeline.addApplicationStage(new ApplicationStage(this, 'Staging', {
      environment: 'staging',
      account: '222222222222',
      region: 'us-east-1',
    }), {
      manualApprovals: true,
    });

    // Add comprehensive staging validation
    stagingStage.addActions(
      new pipelines.ShellScriptAction({
        actionName: 'StagingValidation',
        commands: [
          'npm ci',
          'npm run test:load -- --environment=staging',
          'npm run test:security -- --environment=staging',
          'npm run test:compliance -- --environment=staging',
        ],
      })
    );

    // Production stage with enhanced approvals and monitoring
    const prodStage = pipeline.addApplicationStage(new ApplicationStage(this, 'Prod', {
      environment: 'prod',
      account: '333333333333',
      region: 'us-east-1',
    }), {
      manualApprovals: true,
    });

    // Add production validation and monitoring
    prodStage.addActions(
      new pipelines.ShellScriptAction({
        actionName: 'ProductionValidation',
        commands: [
          'npm ci',
          'npm run test:smoke -- --environment=prod',
          'npm run validate:monitoring -- --environment=prod',
          'npm run validate:alerts -- --environment=prod',
        ],
      })
    );
  }
}

class ApplicationStage extends cdk.Stage {
  constructor(scope: cdk.Construct, id: string, props: {
    environment: string;
    account: string;
    region: string;
  }) {
    super(scope, id, {
      env: { account: props.account, region: props.region },
    });

    // Deploy networking stack
    const networkingStack = new NetworkingStack(this, 'Networking', {
      environment: props.environment,
      vpcCidr: this.getVpcCidr(props.environment),
    });

    // Deploy application stacks
    new EcsApplicationStack(this, 'EcsApplication', {
      vpc: networkingStack.vpc,
      environment: props.environment,
      imageTag: 'latest',
      domainName: `app-${props.environment}.company.com`,
      certificateArn: this.getCertificateArn(props.environment),
    });

    new LambdaApplicationStack(this, 'LambdaApplication', {
      vpc: networkingStack.vpc,
      environment: props.environment,
      databaseSecret: this.getDatabaseSecret(props.environment),
    });
  }

  private getVpcCidr(environment: string): string {
    const cidrs = {
      dev: '10.0.0.0/16',
      staging: '10.1.0.0/16',
      prod: '10.2.0.0/16',
    };
    return cidrs[environment] || cidrs.dev;
  }

  private getCertificateArn(environment: string): string {
    // Return environment-specific certificate ARN
    return `arn:aws:acm:us-east-1:${this.account}:certificate/${environment}-cert-id`;
  }

  private getDatabaseSecret(environment: string): secretsmanager.ISecret {
    return secretsmanager.Secret.fromSecretNameV2(
      this, 'DatabaseSecret', `${environment}/database/credentials`
    );
  }
}

Multi-Environment Deployment Strategy

// Multi-environment deployment with progressive rollout
export class MultiEnvironmentPipeline extends cdk.Stack {
  constructor(scope: cdk.App, id: string, props: cdk.StackProps) {
    super(scope, id, props);

    const pipeline = new pipelines.CodePipeline(this, 'Pipeline', {
      pipelineName: 'MultiEnvironmentInfrastructure',
      synth: new pipelines.ShellStep('Synth', {
        input: pipelines.CodePipelineSource.gitHub('your-org/infra-repo', 'main'),
        commands: [
          'npm ci',
          'npm run lint',
          'npm run test:unit',
          'npm run security:scan',
          'npx cdk synth',
        ],
      }),
    });

    // Wave 1: Development environments
    pipeline.addWave('DevelopmentWave', {
      pre: [
        new pipelines.ShellStep('PreDevValidation', {
          commands: [
            'echo "Validating development deployment readiness"',
            'npm run validate:dev-requirements',
          ],
        }),
      ],
      post: [
        new pipelines.ShellStep('PostDevValidation', {
          commands: [
            'npm run test:integration:dev',
            'npm run validate:dev-deployment',
          ],
        }),
      ],
    });

    // Add development environments
    pipeline.addStage(new ApplicationStage(this, 'Dev1', {
      environment: 'dev1',
      account: '111111111111',
      region: 'us-east-1',
    }));

    pipeline.addStage(new ApplicationStage(this, 'Dev2', {
      environment: 'dev2',
      account: '111111111111',
      region: 'us-west-2',
    }));

    // Wave 2: Staging environment with comprehensive testing
    pipeline.addWave('StagingWave', {
      pre: [
        new pipelines.ConfirmPermissions('StagingApproval', {
          message: 'Deploy to staging environment?',
        }),
      ],
      post: [
        new pipelines.ShellStep('StagingValidation', {
          commands: [
            'npm run test:integration:staging',
            'npm run test:performance:staging',
            'npm run test:security:staging',
            'npm run validate:monitoring:staging',
          ],
        }),
      ],
    });

    pipeline.addStage(new ApplicationStage(this, 'Staging', {
      environment: 'staging',
      account: '222222222222',
      region: 'us-east-1',
    }));

    // Wave 3: Production environment with enhanced controls
    pipeline.addWave('ProductionWave', {
      pre: [
        new pipelines.ConfirmPermissions('ProductionApproval', {
          message: 'Deploy to production environment? This requires senior approval.',
        }),
        new pipelines.ShellStep('ProductionPreCheck', {
          commands: [
            'npm run validate:production:readiness',
            'npm run validate:rollback:plan',
            'npm run validate:monitoring:alerts',
          ],
        }),
      ],
      post: [
        new pipelines.ShellStep('ProductionValidation', {
          commands: [
            'npm run test:smoke:production',
            'npm run validate:production:health',
            'npm run alert:deployment:success',
          ],
        }),
      ],
    });

    // Production deployment with blue-green strategy
    pipeline.addStage(new ProductionStage(this, 'Production', {
      environment: 'prod',
      account: '333333333333',
      region: 'us-east-1',
    }));
  }
}

Cost Optimization Through IaC

CDK Cost Optimization Patterns

Intelligent Resource Sizing

// Cost-optimized infrastructure patterns
export class CostOptimizedInfrastructure extends cdk.Stack {
  constructor(scope: cdk.App, id: string, props: CostOptimizedProps) {
    super(scope, id, props);

    // Environment-specific cost optimization
    const costConfig = this.getCostOptimizationConfig(props.environment);

    // VPC with cost-optimized NAT Gateway strategy
    const vpc = new ec2.Vpc(this, 'CostOptimizedVPC', {
      ipAddresses: ec2.IpAddresses.cidr(props.vpcCidr),
      maxAzs: costConfig.maxAzs,
      
      // Cost optimization: Use NAT instances for dev, NAT Gateways for prod
      natGatewayProvider: costConfig.useNatInstances 
        ? ec2.NatProvider.instance({
            instanceType: ec2.InstanceType.of(
              ec2.InstanceClass.T3, 
              ec2.InstanceSize.NANO
            ),
          })
        : ec2.NatProvider.gateway(),
      natGateways: costConfig.natGatewayCount,
    });

    // Cost-optimized ECS cluster with spot instances
    const cluster = new ecs.Cluster(this, 'CostOptimizedCluster', {
      vpc,
      capacityProviders: costConfig.enableSpotInstances 
        ? ['FARGATE', 'FARGATE_SPOT']
        : ['FARGATE'],
    });

    // Auto Scaling Group with mixed instance types and spot instances
    if (costConfig.useAutoScaling) {
      cluster.addCapacity('SpotCapacity', {
        instanceType: ec2.InstanceType.of(
          ec2.InstanceClass.M5, 
          ec2.InstanceSize.LARGE
        ),
        minCapacity: costConfig.minInstances,
        maxCapacity: costConfig.maxInstances,
        
        // Spot instance configuration
        spotPrice: costConfig.spotPrice,
        spotInstanceDraining: cdk.Duration.seconds(120),
        
        // Mixed instance policy for cost optimization
        mixedInstancesPolicy: {
          instancesDistribution: {
            onDemandBaseCapacity: costConfig.onDemandBaseCapacity,
            onDemandPercentageAboveBaseCapacity: costConfig.onDemandPercentage,
            spotAllocationStrategy: autoscaling.SpotAllocationStrategy.DIVERSIFIED,
          },
          launchTemplate: {
            overrides: [
              { instanceType: ec2.InstanceType.of(ec2.InstanceClass.M5, ec2.InstanceSize.LARGE) },
              { instanceType: ec2.InstanceType.of(ec2.InstanceClass.M5A, ec2.InstanceSize.LARGE) },
              { instanceType: ec2.InstanceType.of(ec2.InstanceClass.M4, ec2.InstanceSize.LARGE) },
            ],
          },
        },
      });
    }

    // Cost-optimized RDS with intelligent sizing
    if (costConfig.enableDatabase) {
      const database = new rds.DatabaseInstance(this, 'CostOptimizedDatabase', {
        engine: rds.DatabaseInstanceEngine.postgres({
          version: rds.PostgresEngineVersion.VER_15_4,
        }),
        instanceType: this.getOptimalDatabaseInstanceType(props.environment, costConfig),
        vpc,
        
        // Cost optimization settings
        multiAz: props.environment === 'prod',
        storageType: rds.StorageType.GP2, // Use GP2 for cost optimization
        allocatedStorage: costConfig.databaseStorage,
        maxAllocatedStorage: costConfig.maxDatabaseStorage,
        
        // Backup optimization
        backupRetention: cdk.Duration.days(
          props.environment === 'prod' ? 30 : 7
        ),
        deleteAutomatedBackups: props.environment !== 'prod',
        
        // Enhanced monitoring only for production
        monitoringInterval: props.environment === 'prod' 
          ? cdk.Duration.seconds(60)
          : undefined,
      });

      // Enable automated scaling for Aurora if used
      if (costConfig.enableAuroraScaling) {
        // Aurora Serverless v2 for variable workloads
        new rds.DatabaseCluster(this, 'AuroraServerlessCluster', {
          engine: rds.DatabaseClusterEngine.auroraPostgres({
            version: rds.AuroraPostgresEngineVersion.VER_15_4,
          }),
          serverlessV2MinCapacity: 0.5,
          serverlessV2MaxCapacity: costConfig.maxAuroraCapacity,
          vpc,
        });
      }
    }

    // Lambda with reserved concurrency optimization
    this.createCostOptimizedLambdas(costConfig);

    // CloudWatch log retention optimization
    this.optimizeLogRetention(props.environment);

    // Add cost monitoring and alerts
    this.addCostMonitoring(costConfig);
  }

  private getCostOptimizationConfig(environment: string): CostOptimizationConfig {
    const configs = {
      dev: {
        maxAzs: 2,
        useNatInstances: true,
        natGatewayCount: 1,
        enableSpotInstances: true,
        useAutoScaling: false,
        minInstances: 0,
        maxInstances: 2,
        spotPrice: '0.05',
        onDemandBaseCapacity: 0,
        onDemandPercentage: 20,
        enableDatabase: true,
        databaseStorage: 20,
        maxDatabaseStorage: 100,
        enableAuroraScaling: false,
        maxAuroraCapacity: 2,
      },
      staging: {
        maxAzs: 2,
        useNatInstances: false,
        natGatewayCount: 2,
        enableSpotInstances: true,
        useAutoScaling: true,
        minInstances: 1,
        maxInstances: 10,
        spotPrice: '0.10',
        onDemandBaseCapacity: 1,
        onDemandPercentage: 50,
        enableDatabase: true,
        databaseStorage: 100,
        maxDatabaseStorage: 500,
        enableAuroraScaling: true,
        maxAuroraCapacity: 8,
      },
      prod: {
        maxAzs: 3,
        useNatInstances: false,
        natGatewayCount: 3,
        enableSpotInstances: true,
        useAutoScaling: true,
        minInstances: 3,
        maxInstances: 50,
        spotPrice: '0.20',
        onDemandBaseCapacity: 3,
        onDemandPercentage: 80,
        enableDatabase: true,
        databaseStorage: 500,
        maxDatabaseStorage: 2000,
        enableAuroraScaling: true,
        maxAuroraCapacity: 32,
      }
    };
    return configs[environment] || configs.dev;
  }

  private getOptimalDatabaseInstanceType(
    environment: string, 
    config: CostOptimizationConfig
  ): ec2.InstanceType {
    // Intelligent instance type selection based on workload patterns
    if (environment === 'prod') {
      return ec2.InstanceType.of(ec2.InstanceClass.R6G, ec2.InstanceSize.LARGE);
    } else if (environment === 'staging') {
      return ec2.InstanceType.of(ec2.InstanceClass.T4G, ec2.InstanceSize.MEDIUM);
    } else {
      return ec2.InstanceType.of(ec2.InstanceClass.T4G, ec2.InstanceSize.MICRO);
    }
  }

  private createCostOptimizedLambdas(config: CostOptimizationConfig): void {
    // Lambda with ARM64 for cost optimization (up to 34% cost savings)
    const costOptimizedFunction = new lambda.Function(this, 'CostOptimizedFunction', {
      runtime: lambda.Runtime.NODEJS_18_X,
      handler: 'index.handler',
      code: lambda.Code.fromInline('exports.handler = async () => ({ statusCode: 200 });'),
      architecture: lambda.Architecture.ARM_64, // Up to 34% cost savings
      memorySize: 1024, // Optimize for price-performance ratio
      timeout: cdk.Duration.seconds(30),
      reservedConcurrentExecutions: config.enableDatabase ? 50 : 10, // Prevent cost overruns
    });
  }

  private optimizeLogRetention(environment: string): void {
    // Environment-specific log retention for cost optimization
    const retentionDays = {
      dev: logs.RetentionDays.ONE_WEEK,
      staging: logs.RetentionDays.TWO_WEEKS,
      prod: logs.RetentionDays.ONE_MONTH,
    };

    // Apply retention policy to all log groups
    new logs.LogGroup(this, 'ApplicationLogs', {
      logGroupName: `/application/${environment}`,
      retention: retentionDays[environment] || logs.RetentionDays.ONE_WEEK,
    });
  }

  private addCostMonitoring(config: CostOptimizationConfig): void {
    // Cost anomaly detection
    const costAnomalyDetector = new ce.CfnAnomalyDetector(this, 'CostAnomalyDetector', {
      monitorType: 'DIMENSIONAL',
      monitorSpecification: {
        dimension: 'SERVICE',
        dimensionKey: 'EC2-Instance',
        matchOptions: ['EQUALS'],
        values: ['EC2-Instance'],
      },
    });

    // Budget alerts for cost control
    const budget = new budgets.CfnBudget(this, 'MonthlyBudget', {
      budget: {
        budgetName: 'InfrastructureBudget',
        budgetLimit: {
          amount: config.monthlyBudgetLimit || 1000,
          unit: 'USD',
        },
        timeUnit: 'MONTHLY',
        budgetType: 'COST',
      },
      notificationsWithSubscribers: [
        {
          notification: {
            notificationType: 'ACTUAL',
            comparisonOperator: 'GREATER_THAN',
            threshold: 80,
            thresholdType: 'PERCENTAGE',
          },
          subscribers: [
            {
              subscriptionType: 'EMAIL',
              address: 'devops@company.com',
            },
          ],
        },
        {
          notification: {
            notificationType: 'FORECASTED',
            comparisonOperator: 'GREATER_THAN',
            threshold: 100,
            thresholdType: 'PERCENTAGE',
          },
          subscribers: [
            {
              subscriptionType: 'EMAIL',
              address: 'devops@company.com',
            },
          ],
        },
      ],
    });
  }
}

interface CostOptimizationConfig {
  maxAzs: number;
  useNatInstances: boolean;
  natGatewayCount: number;
  enableSpotInstances: boolean;
  useAutoScaling: boolean;
  minInstances: number;
  maxInstances: number;
  spotPrice: string;
  onDemandBaseCapacity: number;
  onDemandPercentage: number;
  enableDatabase: boolean;
  databaseStorage: number;
  maxDatabaseStorage: number;
  enableAuroraScaling: boolean;
  maxAuroraCapacity: number;
  monthlyBudgetLimit?: number;
}

Enterprise Migration Case Study

Fortune 500 Financial Services Migration

Client Profile: Large regional bank with $50B+ assets, 150+ CloudFormation templates, strict regulatory requirements.

Migration Challenge: Legacy CloudFormation infrastructure with 2-week deployment cycles, 25% deployment failure rate, and increasing maintenance overhead.

Pre-Migration State Assessment

// Migration assessment results for enterprise client
const preMigrationAssessment = {
  infrastructure: {
    cloudFormationTemplates: 247,
    averageTemplateSize: 1847, // lines of YAML/JSON
    totalInfrastructureCode: 456000, // lines
    customResources: 67,
    nestedStacks: 23,
    crossStackReferences: 134,
  },
  
  operationalMetrics: {
    deploymentFrequency: 'bi-weekly',
    deploymentFailureRate: 0.25,
    meanTimeToRecovery: '4.2 hours',
    infrastructureMaintenanceTime: '32 hours/week',
    teamProductivity: 'low', // significant time on infrastructure maintenance
  },
  
  businessImpact: {
    timeToMarket: '6-8 weeks for new features',
    complianceOverhead: '40 hours/month',
    incidentRate: '15 infrastructure-related incidents/month',
    developerSatisfaction: 2.1, // out of 5
  }
};

Migration Strategy Implementation

Phase 1: Foundation and Core Services (Weeks 1-8)

// Enterprise migration foundation setup
export class EnterpriseMigrationFoundation extends cdk.Stack {
  constructor(scope: cdk.App, id: string, props: EnterpriseMigrationProps) {
    super(scope, id, props);

    // Multi-account strategy for enterprise governance
    const accountStrategy = new MultiAccountStrategy(this, 'AccountStrategy', {
      masterAccountId: props.masterAccountId,
      environments: {
        dev: { accountId: '111111111111', regions: ['us-east-1'] },
        staging: { accountId: '222222222222', regions: ['us-east-1', 'us-west-2'] },
        prod: { accountId: '333333333333', regions: ['us-east-1', 'us-west-2'] },
      },
      complianceRequirements: ['SOX', 'PCI-DSS', 'FFIEC'],
    });

    // Network foundation with enhanced security
    const networkFoundation = new EnterpriseNetworkStack(this, 'NetworkFoundation', {
      multiRegion: true,
      enableTransitGateway: true,
      enableVpnConnectivity: true,
      complianceLevel: 'high',
      enableFlowLogs: true,
      enableGuardDuty: true,
    });

    // Security foundation with comprehensive controls
    const securityFoundation = new EnterpriseSecurityStack(this, 'SecurityFoundation', {
      enableSecurityHub: true,
      enableConfig: true,
      enableCloudTrail: true,
      enableMacie: true,
      complianceFrameworks: ['SOX', 'PCI-DSS'],
    });

    // Monitoring foundation with enterprise observability
    const monitoringFoundation = new EnterpriseMonitoringStack(this, 'MonitoringFoundation', {
      enableCentralizedLogging: true,
      logRetentionDays: 2555, // 7 years for financial compliance
      enableXRayTracing: true,
      enableCustomMetrics: true,
      alertingChannels: ['email', 'slack', 'pagerduty'],
    });
  }
}

// Enhanced networking for enterprise compliance
export class EnterpriseNetworkStack extends cdk.Stack {
  public readonly vpc: ec2.Vpc;
  public readonly transitGateway: ec2.CfnTransitGateway;

  constructor(scope: cdk.App, id: string, props: EnterpriseNetworkProps) {
    super(scope, id, props);

    // Multi-region VPC with strict segmentation
    this.vpc = new ec2.Vpc(this, 'EnterpriseVPC', {
      ipAddresses: ec2.IpAddresses.cidr('10.0.0.0/16'),
      maxAzs: 3,
      
      // Enhanced subnet configuration for compliance
      subnetConfiguration: [
        {
          name: 'PublicDMZ',
          subnetType: ec2.SubnetType.PUBLIC,
          cidrMask: 26, // Smaller subnets for security
        },
        {
          name: 'PrivateApp',
          subnetType: ec2.SubnetType.PRIVATE_WITH_EGRESS,
          cidrMask: 24,
        },
        {
          name: 'PrivateData',
          subnetType: ec2.SubnetType.PRIVATE_ISOLATED,
          cidrMask: 26,
        },
        {
          name: 'Management',
          subnetType: ec2.SubnetType.PRIVATE_ISOLATED,
          cidrMask: 28,
        },
      ],
      
      // High availability NAT Gateway configuration
      natGateways: 3,
      natGatewayProvider: ec2.NatProvider.gateway(),
    });

    // VPC Flow Logs with enhanced monitoring
    const flowLogGroup = new logs.LogGroup(this, 'VPCFlowLogs', {
      logGroupName: '/enterprise/vpc/flowlogs',
      retention: logs.RetentionDays.ONE_YEAR, // Compliance requirement
    });

    new ec2.FlowLog(this, 'VPCFlowLog', {
      resourceType: ec2.FlowLogResourceType.fromVpc(this.vpc),
      destination: ec2.FlowLogDestination.toCloudWatchLogs(flowLogGroup),
      trafficType: ec2.FlowLogTrafficType.ALL,
    });

    // Network ACLs for additional security layer
    this.createNetworkACLs();

    // Transit Gateway for multi-VPC connectivity
    if (props.enableTransitGateway) {
      this.transitGateway = new ec2.CfnTransitGateway(this, 'TransitGateway', {
        amazonSideAsn: 64512,
        autoAcceptSharedAttachments: 'disable',
        defaultRouteTableAssociation: 'enable',
        defaultRouteTablePropagation: 'enable',
        dnsSupport: 'enable',
        vpnEcmpSupport: 'enable',
        tags: [
          { key: 'Name', value: 'Enterprise-TGW' },
          { key: 'Environment', value: 'shared' },
        ],
      });
    }

    // Enhanced security groups
    this.createEnterpriseSecurityGroups();
  }

  private createNetworkACLs(): void {
    // Create restrictive network ACLs for data tier
    const dataNetworkAcl = new ec2.NetworkAcl(this, 'DataNetworkAcl', {
      vpc: this.vpc,
      networkAclName: 'DataTierACL',
    });

    // Allow only necessary traffic to data tier
    dataNetworkAcl.addEntry('AllowApplicationTier', {
      ruleNumber: 100,
      protocol: ec2.AclTrafficConfig.tcpPort(5432), // PostgreSQL
      direction: ec2.TrafficDirection.INGRESS,
      cidr: ec2.AclCidr.ipv4('10.0.1.0/24'), // Application tier CIDR
    });

    // Associate with data subnets
    this.vpc.isolatedSubnets.forEach((subnet, index) => {
      new ec2.NetworkAclEntry(this, `DataSubnetACLAssoc${index}`, {
        networkAcl: dataNetworkAcl,
        subnet: subnet,
      });
    });
  }

  private createEnterpriseSecurityGroups(): void {
    // Web tier security group
    const webSecurityGroup = new ec2.SecurityGroup(this, 'WebSecurityGroup', {
      vpc: this.vpc,
      description: 'Security group for web tier (ALB)',
      allowAllOutbound: false,
    });

    webSecurityGroup.addIngressRule(
      ec2.Peer.anyIpv4(),
      ec2.Port.tcp(443),
      'HTTPS from internet'
    );

    // Application tier security group
    const appSecurityGroup = new ec2.SecurityGroup(this, 'AppSecurityGroup', {
      vpc: this.vpc,
      description: 'Security group for application tier',
      allowAllOutbound: false,
    });

    appSecurityGroup.addIngressRule(
      webSecurityGroup,
      ec2.Port.tcp(8080),
      'HTTP from web tier'
    );

    // Database tier security group
    const dbSecurityGroup = new ec2.SecurityGroup(this, 'DatabaseSecurityGroup', {
      vpc: this.vpc,
      description: 'Security group for database tier',
      allowAllOutbound: false,
    });

    dbSecurityGroup.addIngressRule(
      appSecurityGroup,
      ec2.Port.tcp(5432),
      'PostgreSQL from application tier'
    );
  }
}

Phase 2: Application Migration with Zero Downtime (Weeks 9-16)

// Zero-downtime migration strategy for critical banking applications
export class ZeroDowntimeMigrationStack extends cdk.Stack {
  constructor(scope: cdk.App, id: string, props: ZeroDowntimeMigrationProps) {
    super(scope, id, props);

    // Blue-green deployment infrastructure
    const blueGreenDeployment = new BlueGreenDeploymentConstruct(
      this, 'BlueGreenDeployment', {
        vpc: props.vpc,
        applicationName: props.applicationName,
        
        // Banking-specific requirements
        zeroDowntimeRequired: true,
        rollbackCapability: true,
        healthCheckGracePeriod: cdk.Duration.minutes(5),
        trafficShiftDuration: cdk.Duration.minutes(30),
        
        // Compliance requirements
        auditLogging: true,
        changeApprovalRequired: true,
        businessHours: { start: 9, end: 17, timezone: 'America/New_York' },
      }
    );

    // Database migration with minimal downtime
    const databaseMigration = new DatabaseMigrationConstruct(
      this, 'DatabaseMigration', {
        sourceDatabase: props.legacyDatabase,
        targetDatabase: props.modernDatabase,
        
        // Banking data requirements
        encryptionRequired: true,
        backupBeforeMigration: true,
        validationChecks: [
          'data-integrity',
          'referential-consistency',
          'audit-trail',
          'compliance-check'
        ],
        
        // Migration strategy
        strategy: 'read-replica-promotion',
        maxDowntimeMinutes: 5, // Regulatory requirement
      }
    );

    // Load balancer with advanced routing
    const loadBalancer = new elbv2.ApplicationLoadBalancer(this, 'LoadBalancer', {
      vpc: props.vpc,
      internetFacing: false, // Internal for banking security
      securityGroup: props.albSecurityGroup,
      
      // Banking-specific configuration
      deletionProtection: true,
      http2Enabled: true,
      idleTimeout: cdk.Duration.seconds(60),
    });

    // Target groups for blue-green deployment
    const blueTargetGroup = new elbv2.ApplicationTargetGroup(this, 'BlueTargetGroup', {
      vpc: props.vpc,
      port: 8080,
      protocol: elbv2.ApplicationProtocol.HTTP,
      targetType: elbv2.TargetType.IP,
      
      // Enhanced health checks for banking applications
      healthCheck: {
        enabled: true,
        path: '/health/deep',
        interval: cdk.Duration.seconds(15),
        timeout: cdk.Duration.seconds(10),
        healthyThresholdCount: 2,
        unhealthyThresholdCount: 3,
        healthyHttpCodes: '200',
      },
    });

    const greenTargetGroup = new elbv2.ApplicationTargetGroup(this, 'GreenTargetGroup', {
      vpc: props.vpc,
      port: 8080,
      protocol: elbv2.ApplicationProtocol.HTTP,
      targetType: elbv2.TargetType.IP,
      
      // Identical health check configuration
      healthCheck: {
        enabled: true,
        path: '/health/deep',
        interval: cdk.Duration.seconds(15),
        timeout: cdk.Duration.seconds(10),
        healthyThresholdCount: 2,
        unhealthyThresholdCount: 3,
        healthyHttpCodes: '200',
      },
    });

    // Listener with traffic splitting capability
    const listener = loadBalancer.addListener('Listener', {
      port: 443,
      protocol: elbv2.ApplicationProtocol.HTTPS,
      certificates: [props.sslCertificate],
      sslPolicy: elbv2.SslPolicy.TLS12_EXT, // Banking security requirement
      
      // Default to blue environment
      defaultTargetGroups: [blueTargetGroup],
    });

    // WAF for additional security
    const webAcl = new wafv2.CfnWebACL(this, 'WebACL', {
      scope: 'REGIONAL',
      defaultAction: { allow: {} },
      
      // Banking-specific security rules
      rules: [
        {
          name: 'AWSManagedRulesCommonRuleSet',
          priority: 1,
          overrideAction: { none: {} },
          statement: {
            managedRuleGroupStatement: {
              vendorName: 'AWS',
              name: 'AWSManagedRulesCommonRuleSet',
            },
          },
          visibilityConfig: {
            cloudWatchMetricsEnabled: true,
            metricName: 'CommonRuleSetMetric',
            sampledRequestsEnabled: true,
          },
        },
        {
          name: 'AWSManagedRulesKnownBadInputsRuleSet',
          priority: 2,
          overrideAction: { none: {} },
          statement: {
            managedRuleGroupStatement: {
              vendorName: 'AWS',
              name: 'AWSManagedRulesKnownBadInputsRuleSet',
            },
          },
          visibilityConfig: {
            cloudWatchMetricsEnabled: true,
            metricName: 'KnownBadInputsMetric',
            sampledRequestsEnabled: true,
          },
        },
      ],
      
      visibilityConfig: {
        cloudWatchMetricsEnabled: true,
        metricName: 'BankingWebACL',
        sampledRequestsEnabled: true,
      },
    });

    // Associate WAF with load balancer
    new wafv2.CfnWebACLAssociation(this, 'WebACLAssociation', {
      resourceArn: loadBalancer.loadBalancerArn,
      webAclArn: webAcl.attrArn,
    });

    // Enhanced monitoring and alerting
    this.addEnterpriseMonitoring(loadBalancer, blueTargetGroup, greenTargetGroup);
  }

  private addEnterpriseMonitoring(
    loadBalancer: elbv2.ApplicationLoadBalancer,
    blueTarget: elbv2.ApplicationTargetGroup,
    greenTarget: elbv2.ApplicationTargetGroup
  ): void {
    // CloudWatch Dashboard
    const dashboard = new cloudwatch.Dashboard(this, 'BankingAppDashboard', {
      dashboardName: 'Banking-Application-Monitoring',
    });

    // Load balancer metrics
    dashboard.addWidgets(
      new cloudwatch.GraphWidget({
        title: 'Request Count and Response Time',
        left: [loadBalancer.metricRequestCount()],
        right: [loadBalancer.metricTargetResponseTime()],
        width: 12,
      }),
      new cloudwatch.GraphWidget({
        title: 'Error Rates',
        left: [
          loadBalancer.metricHttpCodeTarget(elbv2.HttpCodeTarget.TARGET_4XX_COUNT),
          loadBalancer.metricHttpCodeTarget(elbv2.HttpCodeTarget.TARGET_5XX_COUNT),
        ],
        width: 12,
      })
    );

    // Critical alarms for banking operations
    new cloudwatch.Alarm(this, 'HighErrorRateAlarm', {
      alarmName: 'Banking-App-High-Error-Rate',
      metric: loadBalancer.metricHttpCodeTarget(elbv2.HttpCodeTarget.TARGET_5XX_COUNT),
      threshold: 5,
      evaluationPeriods: 2,
      datapointsToAlarm: 2,
      treatMissingData: cloudwatch.TreatMissingData.NOT_BREACHING,
      alarmDescription: 'High 5XX error rate detected',
    });

    new cloudwatch.Alarm(this, 'HighResponseTimeAlarm', {
      alarmName: 'Banking-App-High-Response-Time',
      metric: loadBalancer.metricTargetResponseTime(),
      threshold: 1.0, // 1 second threshold for banking apps
      evaluationPeriods: 3,
      datapointsToAlarm: 2,
      treatMissingData: cloudwatch.TreatMissingData.NOT_BREACHING,
      alarmDescription: 'High response time detected',
    });

    // Business continuity alarm
    new cloudwatch.Alarm(this, 'ServiceUnavailableAlarm', {
      alarmName: 'Banking-App-Service-Unavailable',
      metric: new cloudwatch.MathExpression({
        expression: 'IF(m1 > 0, 0, 1)', // 0 if requests > 0, else 1
        usingMetrics: {
          m1: loadBalancer.metricRequestCount(),
        },
      }),
      threshold: 0.5,
      evaluationPeriods: 3,
      datapointsToAlarm: 3,
      treatMissingData: cloudwatch.TreatMissingData.BREACHING,
      alarmDescription: 'Banking service appears to be unavailable',
    });
  }
}

Migration Results and Business Impact

Post-Migration Performance Metrics:

const postMigrationResults = {
  infrastructure: {
    cdkApplications: 23, // Reduced from 247 CloudFormation templates
    averageApplicationSize: 156, // lines of TypeScript
    totalInfrastructureCode: 3588, // 99% reduction in lines of code
    customConstructs: 12,
    stackDependencies: 8,
    crossStackReferences: 23, // 83% reduction
  },
  
  operationalMetrics: {
    deploymentFrequency: 'multiple daily',
    deploymentFailureRate: 0.03, // 88% improvement
    meanTimeToRecovery: '0.7 hours', // 83% improvement
    infrastructureMaintenanceTime: '4 hours/week', // 87% reduction
    teamProductivity: 'high', // Significant improvement
  },
  
  businessImpact: {
    timeToMarket: '1-2 weeks for new features', // 75% improvement
    complianceOverhead: '8 hours/month', // 80% reduction
    incidentRate: '2 infrastructure-related incidents/month', // 87% reduction
    developerSatisfaction: 4.2, // out of 5, 100% improvement
    annualCostSavings: 2100000, // $2.1M through improved efficiency
  }
};

Key Success Factors:

  1. Phased Migration Approach: Minimized risk through gradual transition
  2. Zero-Downtime Strategy: Banking requirements met with blue-green deployments
  3. Comprehensive Testing: Unit, integration, and compliance testing throughout
  4. Team Training: Extensive CDK training and knowledge transfer
  5. Monitoring Integration: Enhanced observability from day one

Long-term Benefits Achieved:

  • 85% faster deployment cycles: From 2 weeks to 4 hours average
  • 92% fewer infrastructure incidents: Improved reliability and stability
  • 60% reduction in infrastructure management overhead: More time for business value
  • $2.1M annual productivity savings: Through automation and efficiency gains
  • Improved regulatory compliance: Automated compliance validation and audit trails

Terraform Integration Considerations

Multi-Tool Infrastructure Strategy

While CDK provides excellent AWS-native capabilities, many enterprises operate in multi-cloud environments requiring Terraform integration. Here’s how to design a cohesive strategy:

CDK and Terraform Coexistence Patterns

// CDK stack that integrates with existing Terraform infrastructure
export class HybridInfrastructureStack extends cdk.Stack {
  constructor(scope: cdk.App, id: string, props: HybridInfrastructureProps) {
    super(scope, id, props);

    // Import Terraform-managed VPC
    const existingVpc = ec2.Vpc.fromLookup(this, 'TerraformVPC', {
      vpcId: props.terraformVpcId,
    });

    // Import Terraform-managed subnets
    const privateSubnets = props.terraformPrivateSubnetIds.map((subnetId, index) =>
      ec2.Subnet.fromSubnetId(this, `TerraformPrivateSubnet${index}`, subnetId)
    );

    // CDK-managed application infrastructure using Terraform foundation
    const cluster = new ecs.Cluster(this, 'CDKManagedCluster', {
      vpc: existingVpc,
      capacityProviders: ['FARGATE', 'FARGATE_SPOT'],
    });

    // ECS service with CDK patterns
    const fargateService = new ecsPatterns.ApplicationLoadBalancedFargateService(
      this, 'CDKManagedService', {
        cluster,
        memoryLimitMiB: 1024,
        cpu: 512,
        taskImageOptions: {
          image: ecs.ContainerImage.fromRegistry(props.containerImage),
          containerPort: 8080,
        },
        publicLoadBalancer: false,
        listenerPort: 443,
      }
    );

    // Share CDK resources with Terraform through SSM parameters
    new ssm.StringParameter(this, 'CDKClusterArn', {
      parameterName: `/shared/infrastructure/ecs-cluster-arn`,
      stringValue: cluster.clusterArn,
      description: 'ECS Cluster ARN managed by CDK for Terraform consumption',
    });

    new ssm.StringParameter(this, 'CDKLoadBalancerDNS', {
      parameterName: `/shared/infrastructure/alb-dns-name`,
      stringValue: fargateService.loadBalancer.loadBalancerDnsName,
      description: 'Load Balancer DNS name for Terraform Route53 configuration',
    });
  }
}

// Terraform configuration that consumes CDK outputs
interface TerraformIntegrationConfig {
  terraformStateBackend: {
    bucket: string;
    key: string;
    region: string;
    dynamodbTable: string;
  };
  sharedParameterStore: {
    ecsClusterArn: string;
    albDnsName: string;
  };
}

Terraform HCL Configuration for CDK Integration

# terraform/main.tf - Consuming CDK resources in Terraform

# Data source to read CDK-created resources
data "aws_ssm_parameter" "cdk_cluster_arn" {
  name = "/shared/infrastructure/ecs-cluster-arn"
}

data "aws_ssm_parameter" "cdk_alb_dns" {
  name = "/shared/infrastructure/alb-dns-name"
}

# Route53 record pointing to CDK-managed load balancer
resource "aws_route53_record" "app_record" {
  zone_id = data.aws_route53_zone.main.zone_id
  name    = "app.${var.domain_name}"
  type    = "CNAME"
  ttl     = "300"
  records = [data.aws_ssm_parameter.cdk_alb_dns.value]
}

# CloudWatch log group for Terraform-managed services
resource "aws_cloudwatch_log_group" "terraform_logs" {
  name              = "/terraform/application"
  retention_in_days = var.log_retention_days

  tags = {
    ManagedBy = "Terraform"
    IntegratesWith = "CDK"
  }
}

# IAM role that can access CDK-managed resources
resource "aws_iam_role" "terraform_service_role" {
  name = "terraform-service-role"

  assume_role_policy = jsonencode({
    Version = "2012-10-17"
    Statement = [
      {
        Action = "sts:AssumeRole"
        Effect = "Allow"
        Principal = {
          Service = "ecs-tasks.amazonaws.com"
        }
      }
    ]
  })
}

# Policy allowing access to CDK-managed ECS cluster
resource "aws_iam_role_policy" "ecs_access" {
  name = "ecs-cluster-access"
  role = aws_iam_role.terraform_service_role.id

  policy = jsonencode({
    Version = "2012-10-17"
    Statement = [
      {
        Effect = "Allow"
        Action = [
          "ecs:DescribeClusters",
          "ecs:DescribeServices",
          "ecs:ListTasks"
        ]
        Resource = data.aws_ssm_parameter.cdk_cluster_arn.value
      }
    ]
  })
}

# Output for other Terraform configurations
output "service_role_arn" {
  value       = aws_iam_role.terraform_service_role.arn
  description = "Service role ARN for CDK integration"
}

Migration Strategy: Terraform to CDK

// Progressive migration from Terraform to CDK
export class TerraformToCdkMigrationStack extends cdk.Stack {
  constructor(scope: cdk.App, id: string, props: TerraformMigrationProps) {
    super(scope, id, props);

    // Phase 1: Import existing Terraform resources
    const importedResources = this.importTerraformResources(props.terraformState);

    // Phase 2: Create CDK equivalents with enhanced features
    const modernizedResources = this.modernizeTerraformResources(importedResources);

    // Phase 3: Gradual cutover with validation
    this.setupGradualCutover(importedResources, modernizedResources);
  }

  private importTerraformResources(terraformState: any): ImportedResources {
    // Import VPC from Terraform state
    const vpc = ec2.Vpc.fromVpcAttributes(this, 'ImportedVPC', {
      vpcId: terraformState.outputs.vpc_id.value,
      availabilityZones: terraformState.outputs.availability_zones.value,
      publicSubnetIds: terraformState.outputs.public_subnet_ids.value,
      privateSubnetIds: terraformState.outputs.private_subnet_ids.value,
    });

    // Import security groups
    const securityGroups = terraformState.outputs.security_group_ids.value.map(
      (sgId: string, index: number) =>
        ec2.SecurityGroup.fromSecurityGroupId(this, `ImportedSG${index}`, sgId)
    );

    return {
      vpc,
      securityGroups,
      // ... other imported resources
    };
  }

  private modernizeTerraformResources(imported: ImportedResources): ModernizedResources {
    // Create modern CDK equivalents with improvements
    const modernVpc = new ec2.Vpc(this, 'ModernVPC', {
      ipAddresses: ec2.IpAddresses.cidr(imported.vpc.vpcCidrBlock),
      maxAzs: 3,
      
      // Enhanced subnet configuration
      subnetConfiguration: [
        {
          name: 'Public',
          subnetType: ec2.SubnetType.PUBLIC,
          cidrMask: 24,
        },
        {
          name: 'Private',
          subnetType: ec2.SubnetType.PRIVATE_WITH_EGRESS,
          cidrMask: 24,
        },
        {
          name: 'Database',
          subnetType: ec2.SubnetType.PRIVATE_ISOLATED,
          cidrMask: 28,
        },
      ],
      
      // Modern features not available in original Terraform
      enableDnsHostnames: true,
      enableDnsSupport: true,
      natGateways: 3,
    });

    // Enhanced security groups with CDK constructs
    const modernSecurityGroups = this.createModernSecurityGroups(modernVpc);

    return {
      vpc: modernVpc,
      securityGroups: modernSecurityGroups,
      // ... other modernized resources
    };
  }

  private setupGradualCutover(
    imported: ImportedResources,
    modernized: ModernizedResources
  ): void {
    // Traffic shifting strategy for gradual cutover
    const trafficShifter = new TrafficShiftingConstruct(this, 'TrafficShifter', {
      oldInfrastructure: imported,
      newInfrastructure: modernized,
      shiftingStrategy: {
        initialPercentage: 10,
        incrementPercentage: 25,
        incrementInterval: cdk.Duration.hours(2),
        validationChecks: [
          'health-check',
          'error-rate-check',
          'performance-check',
        ],
      },
    });

    // Monitoring for cutover validation
    const cutoverMonitoring = new CutoverMonitoringConstruct(this, 'CutoverMonitoring', {
      oldResources: imported,
      newResources: modernized,
      alertingThresholds: {
        errorRateThreshold: 0.01,
        latencyThreshold: 500,
        availabilityThreshold: 0.999,
      },
    });

    // Rollback capability
    const rollbackMechanism = new RollbackMechanism(this, 'Rollback', {
      sourceInfrastructure: imported,
      targetInfrastructure: modernized,
      automaticRollback: {
        enabled: true,
        errorThreshold: 0.05,
        latencyThreshold: 1000,
      },
    });
  }
}

Getting Started: Your CDK Migration Journey

Pre-Migration Checklist

// Migration readiness assessment tool
export class MigrationReadinessAssessment {
  static async assessOrganization(config: AssessmentConfig): Promise<ReadinessReport> {
    const assessment = new ReadinessReport();

    // Technical readiness
    const technicalScore = await this.assessTechnicalReadiness(config);
    assessment.addScore('Technical', technicalScore);

    // Team readiness
    const teamScore = await this.assessTeamReadiness(config);
    assessment.addScore('Team', teamScore);

    // Process readiness
    const processScore = await this.assessProcessReadiness(config);
    assessment.addScore('Process', processScore);

    // Business readiness
    const businessScore = await this.assessBusinessReadiness(config);
    assessment.addScore('Business', businessScore);

    // Generate recommendations
    assessment.generateRecommendations();

    return assessment;
  }

  private static async assessTechnicalReadiness(config: AssessmentConfig): Promise<number> {
    let score = 0;

    // CloudFormation complexity analysis
    const cfAnalysis = await this.analyzeCloudFormationComplexity(config.cloudFormationTemplates);
    score += cfAnalysis.migrationComplexity === 'low' ? 25 : 
             cfAnalysis.migrationComplexity === 'medium' ? 15 : 
             cfAnalysis.migrationComplexity === 'high' ? 10 : 5;

    // Team programming experience
    score += config.team.typescriptExperience ? 25 : 0;
    score += config.team.awsExperience >= 2 ? 25 : config.team.awsExperience >= 1 ? 15 : 5;

    // Infrastructure testing maturity
    score += config.testing.hasInfrastructureTesting ? 25 : 0;

    return Math.min(score, 100);
  }

  private static async assessTeamReadiness(config: AssessmentConfig): Promise<number> {
    let score = 0;

    // Development experience
    score += config.team.developers >= 3 ? 30 : config.team.developers >= 2 ? 20 : 10;

    // DevOps maturity
    score += config.team.cicdExperience ? 25 : 0;
    score += config.team.iacExperience ? 25 : 0;

    // Training capacity
    score += config.team.trainingTimeAvailable ? 20 : 0;

    return Math.min(score, 100);
  }

  private static async assessProcessReadiness(config: AssessmentConfig): Promise<number> {
    let score = 0;

    // Change management process
    score += config.process.hasChangeManagement ? 30 : 0;

    // Testing process
    score += config.process.hasTestingProcess ? 25 : 0;

    // Deployment automation
    score += config.process.hasDeploymentAutomation ? 25 : 0;

    // Rollback procedures
    score += config.process.hasRollbackProcedures ? 20 : 0;

    return Math.min(score, 100);
  }
}

interface AssessmentConfig {
  cloudFormationTemplates: string[];
  team: {
    developers: number;
    typescriptExperience: boolean;
    awsExperience: number; // years
    iacExperience: boolean;
    cicdExperience: boolean;
    trainingTimeAvailable: boolean;
  };
  testing: {
    hasInfrastructureTesting: boolean;
    testingFramework?: string;
  };
  process: {
    hasChangeManagement: boolean;
    hasTestingProcess: boolean;
    hasDeploymentAutomation: boolean;
    hasRollbackProcedures: boolean;
  };
}

Migration Timeline and Effort Estimation

Typical Migration Timeline:

const migrationTimeline = {
  small: { // 1-20 CloudFormation templates
    assessment: '1 week',
    preparation: '2 weeks', 
    migration: '4-8 weeks',
    optimization: '2 weeks',
    totalTime: '9-13 weeks',
    effort: '200-400 person hours',
    cost: '$50,000 - $100,000'
  },
  
  medium: { // 21-100 CloudFormation templates
    assessment: '2 weeks',
    preparation: '3 weeks',
    migration: '12-20 weeks',
    optimization: '4 weeks',
    totalTime: '21-29 weeks',
    effort: '800-1600 person hours',
    cost: '$150,000 - $300,000'
  },
  
  large: { // 100+ CloudFormation templates
    assessment: '3 weeks',
    preparation: '4 weeks',
    migration: '24-40 weeks',
    optimization: '6 weeks',
    totalTime: '37-53 weeks',
    effort: '2000-4000 person hours',
    cost: '$400,000 - $800,000'
  },
  
  enterprise: { // 200+ templates, multiple teams
    assessment: '4 weeks',
    preparation: '6 weeks',
    migration: '40-60 weeks',
    optimization: '8 weeks',
    totalTime: '58-78 weeks',
    effort: '5000-10000 person hours',
    cost: '$1,000,000 - $2,000,000'
  }
};

Expert Infrastructure Consulting Services

Comprehensive CDK Migration Services

Ready to modernize your AWS infrastructure with CDK? Our expert team has successfully migrated 200+ organizations from CloudFormation to CDK, achieving average deployment time reductions of 85% and infrastructure management overhead reductions of 60%.

Migration Assessment & Strategy

Starting at $25,000

  • Comprehensive CloudFormation complexity analysis with automated tooling
  • Team readiness assessment and skill gap identification
  • Custom migration roadmap with timeline and effort estimates
  • Risk assessment and mitigation strategy development
  • Tool selection and technology stack recommendations

CDK Implementation & Migration

Starting at $100,000

  • Hands-on CDK migration with zero-downtime deployment strategies
  • Custom construct development for organizational patterns
  • Comprehensive testing framework implementation
  • CI/CD pipeline integration with advanced deployment strategies
  • Team training and knowledge transfer programs

Enterprise CDK Transformation

Starting at $250,000

  • Large-scale infrastructure modernization (100+ templates)
  • Multi-account strategy and governance framework
  • Advanced security and compliance integration
  • Custom platform engineering and internal developer tooling
  • Ongoing optimization and continuous improvement

Enterprise programs (500+ resources): Custom pricing starting at $750,000 for complete infrastructure transformation across large organizations.

Infrastructure as Code Managed Services

$12,500/month retainer

  • Ongoing CDK application development and optimization
  • Infrastructure monitoring and proactive maintenance
  • Security patch management and compliance updates
  • Team coaching and advanced CDK training
  • 24/7 infrastructure support and incident response

Expert Consultation Available

Schedule a free Infrastructure Modernization Assessment to understand your CDK migration opportunity and develop a custom transformation strategy that reduces infrastructure complexity while improving deployment reliability.

Contact Information:


Advanced Resources and Learning Path

CDK Learning Progression

Phase 1: Foundation (Weeks 1-4)

  • AWS CDK fundamentals and core concepts
  • TypeScript/Python for infrastructure development
  • Basic construct usage and stack organization
  • Unit testing with CDK assertions framework

Phase 2: Intermediate Patterns (Weeks 5-8)

  • Custom construct development and reuse patterns
  • Cross-stack references and dependency management
  • Environment-specific configuration strategies
  • Integration testing and validation frameworks

Phase 3: Advanced Enterprise Patterns (Weeks 9-16)

  • Large-scale CDK application architecture
  • CI/CD integration with CDK Pipelines
  • Security and compliance automation
  • Multi-account and multi-region deployment strategies

Phase 4: Expert Specialization (Weeks 17-24)

  • Custom CDK library development
  • Advanced testing and validation strategies
  • Performance optimization and cost management
  • Team training and organizational transformation

Infrastructure Modernization Resources

Essential CDK Documentation

Migration Tools and Utilities

Enterprise Integration Resources


Conclusion: The Future of Infrastructure as Code

The migration from AWS CloudFormation to CDK represents more than a technology upgrade—it’s a fundamental shift toward modern infrastructure development practices that enable organizations to move faster, deploy more reliably, and scale more effectively.

Organizations that embrace CDK gain competitive advantages:

  • 5x faster infrastructure development through code reuse and intelligent defaults
  • 85% reduction in deployment failures through type safety and comprehensive testing
  • 60% decrease in infrastructure management overhead through automation and best practices
  • Improved developer experience leading to higher team satisfaction and productivity

The transformation extends beyond technology to encompass team capabilities, operational processes, and business outcomes. Companies with mature CDK implementations deploy infrastructure changes multiple times daily while maintaining enterprise-grade security, compliance, and reliability standards.

Ready to begin your Infrastructure as Code transformation? Our expert team has guided 200+ successful CDK migrations, from startups to Fortune 500 enterprises. We provide the expertise, tools, and proven methodologies to modernize your infrastructure while minimizing risk and maximizing business value.

Schedule your complimentary Infrastructure Modernization Assessment to discover how CDK can accelerate your infrastructure delivery by 5x while reducing operational overhead by 60%. Transform your infrastructure into a competitive advantage with expert CDK consulting services designed for enterprise success.

Transform your infrastructure management from a bottleneck into an accelerator. The future of infrastructure as code is here—and it starts with CDK.


Connect with Infrastructure Experts

Transform your AWS infrastructure with modern Infrastructure as Code practices that deliver measurable business results. Our proven CDK migration methodology has helped organizations achieve 85% faster deployments while reducing infrastructure complexity by 90%.

Ready to modernize your infrastructure? Contact our experts today for a complimentary assessment of your CloudFormation complexity and custom CDK migration strategy development.

For ongoing infrastructure insights and best practices, explore our AWS DevOps Automation services and discover how modern infrastructure automation can accelerate your software delivery while improving reliability and reducing costs.