AWS Essentials¶

AWS is the leading cloud platform. Key services: EC2 (virtual servers), S3 (object storage), RDS (managed databases), Lambda (serverless functions), SQS/SNS (messaging), ECS/EKS (containers), CloudFront (CDN), IAM (access control). Design for the cloud: use managed services, design for failure, auto-scale, decouple components.

Key Concepts¶

Deep Dive: Core Services

Service	Category	Purpose
EC2	Compute	Virtual machines
Lambda	Compute	Serverless functions
S3	Storage	Object storage (files, images)
RDS	Database	Managed SQL (PostgreSQL, MySQL)
DynamoDB	Database	Managed NoSQL (key-value)
SQS	Messaging	Message queue
SNS	Messaging	Pub/sub notifications
ECS/EKS	Containers	Container orchestration
CloudFront	CDN	Content delivery
Route 53	DNS	Domain name system
IAM	Security	Identity and access management
VPC	Networking	Virtual private cloud

Deep Dive: Typical Spring Boot Deployment on AWS

Route 53 (DNS) → CloudFront (CDN) → ALB (Load Balancer)
                                       ↓
                            ┌──── ECS/EKS ────┐
                            │  Spring Boot     │
                            │  Container × 3   │
                            └────────┬─────────┘
                                     ↓
                    RDS (PostgreSQL)  +  ElastiCache (Redis)
                                     +  S3 (file storage)
                                     +  SQS (async processing)

Deep Dive: IAM (Identity & Access Management)

Principle of least privilege — grant only permissions needed.

Users — individual people
Roles — assumed by services (EC2, Lambda, ECS)
Policies — JSON documents defining permissions
Groups — collection of users with shared policies

Common Interview Questions

What AWS services would you use for a web application?
What is the difference between SQS and SNS?
How would you deploy a Spring Boot app on AWS?
What is an IAM role vs IAM user?
What is S3? What storage classes exist?
How does auto-scaling work on AWS?
What is a VPC?