Answer: Host the application on Amazon Elastic Container Service (Amazon ECS). Set up an Application Load Balancer with Amazon ECS as the target.

## Explanation **Correct Answer: D - Host the application on Amazon Elastic Container Service (Amazon ECS). Set up an Application Load Balancer with Amazon ECS as the target.** Here's why this is the best solution: ### Key Requirements Analysis: 1. **Migrate existing monolithic application** - The company wants to keep as much code as possible 2. **Break into smaller applications** - Different teams will manage each application 3. **Highly scalable solution** - Needs to handle varying loads 4. **Minimize operational overhead** - Reduce management burden ### Why Amazon ECS is the Best Choice: **Containerization Benefits:** - **Code Preservation**: ECS allows you to containerize your existing monolithic application with minimal code changes. You can package the application in Docker containers, preserving most of your existing codebase. - **Microservices Transition**: ECS is ideal for breaking monolithic applications into smaller, independently deployable services. Each team can manage their own containerized application components. - **Team Independence**: Different teams can develop, deploy, and scale their specific containerized services independently. **Scalability and Management:** - **Auto Scaling**: ECS integrates with AWS Auto Scaling to automatically scale services based on demand. - **Load Balancing**: Application Load Balancer distributes traffic across multiple ECS tasks, providing high availability and scalability. - **Operational Overhead Reduction**: ECS manages container orchestration, scheduling, and cluster management, reducing operational burden compared to managing EC2 instances directly. ### Why Other Options Are Less Suitable: **A. AWS Lambda with API Gateway:** - Requires significant code refactoring to fit serverless architecture - Not ideal for preserving existing monolithic code structure - Better for event-driven, stateless applications rather than migrating existing monoliths **B. AWS Amplify with Lambda:** - Amplify is primarily for modern web/mobile applications with serverless backends - Requires major architectural changes - Not suitable for migrating existing monolithic applications with minimal code changes **C. EC2 with Auto Scaling:** - While scalable, this maintains the monolithic architecture - Doesn't facilitate breaking into smaller applications managed by different teams - Higher operational overhead for managing EC2 instances, OS patches, etc. ### Additional Benefits of ECS Solution: - **Service Discovery**: ECS integrates with AWS Cloud Map for service discovery between microservices - **Monitoring**: Integrates with Amazon CloudWatch for comprehensive monitoring - **Security**: IAM roles for tasks provide secure access to AWS resources - **Cost Optimization**: Can use Fargate launch type for serverless container management This solution allows the company to gradually decompose their monolith into microservices while maintaining operational efficiency and scalability.