AWS Solution Architecture Guide

Serverless, scalable, and cost-effective AWS cloud infrastructure.

When to Use

• Designing AWS architecture for new applications

• Optimizing AWS costs

• Building serverless applications

• Creating infrastructure as code

• Multi-region deployments

Architecture Patterns

1. Serverless Web Application

Best for: SaaS platforms, mobile backends, low-traffic sites

Frontend: S3 + CloudFront API: API Gateway + Lambda Database: DynamoDB or Aurora Serverless Auth: Cognito CI/CD: Amplify or CodePipeline

Cost: $50-500/month

2. Event-Driven Microservices

Best for: Complex workflows, async processing

Events: EventBridge Processing: Lambda or ECS Fargate Queue: SQS (with DLQ) State: Step Functions Storage: DynamoDB, S3

Cost: $100-1000/month

3. Modern Three-Tier

Best for: Traditional web apps, e-commerce

Load Balancer: ALB Compute: ECS Fargate or EC2 Auto Scaling Database: RDS Aurora Cache: ElastiCache Redis CDN: CloudFront

Cost: $300-2000/month

Service Selection Guide

Compute

Service Use Case

Lambda Event-driven, short tasks (<15 min)

Fargate Containerized apps, long-running

EC2 Custom configs, GPU/FPGA

App Runner Simple container deployment

Database

Service Use Case

DynamoDB Key-value, serverless, <10ms latency

Aurora Serverless Relational, variable workloads

RDS Traditional databases

DocumentDB MongoDB-compatible

Neptune Graph database

Storage

Service Use Case

S3 Standard Frequent access

S3 IA Backups, archives

S3 Glacier Long-term archives

EFS Shared file system

EBS Block storage for EC2

Infrastructure as Code

CDK Example

import * as cdk from 'aws-cdk-lib'; import * as lambda from 'aws-cdk-lib/aws-lambda'; import * as apigateway from 'aws-cdk-lib/aws-apigateway';

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

const handler = new lambda.Function(this, 'Handler', {
  runtime: lambda.Runtime.NODEJS_18_X,
  code: lambda.Code.fromAsset('lambda'),
  handler: 'index.handler',
});

new apigateway.LambdaRestApi(this, 'Api', {
  handler,
});

} }

CloudFormation Snippet

Resources: MyFunction: Type: AWS::Lambda::Function Properties: Runtime: nodejs18.x Handler: index.handler Code: S3Bucket: !Ref CodeBucket S3Key: function.zip MemorySize: 256 Timeout: 30

Cost Optimization

Quick Wins

• Enable S3 Intelligent-Tiering

• Use Savings Plans for predictable workloads

• Set CloudWatch log retention (7-30 days)

• Use VPC endpoints instead of NAT Gateway

• Right-size Lambda memory

Cost Breakdown Tips

• Enable Cost Explorer

• Set up billing alerts

• Tag all resources for tracking

• Review NAT Gateway traffic

• Check data transfer costs

Security Best Practices

Practice Implementation

Least Privilege IAM roles with minimal permissions

Encryption KMS for at-rest, TLS for transit

Network Isolation Private subnets, security groups

Secrets Secrets Manager, not hardcoded

API Protection WAF, rate limiting, API keys

Audit Logging CloudTrail, VPC Flow Logs

Startup Stages

MVP ($20-100/month)

• Amplify full-stack

• Lambda + API Gateway + DynamoDB

• Cognito for auth

• S3 + CloudFront for frontend

Growth Stage ($500-2000/month)

• Add ElastiCache

• Aurora Serverless for complex queries

• CloudWatch dashboards and alarms

• CI/CD pipeline

• Multi-AZ deployment

Scale-Up ($3000-10000/month)

• Multi-region deployment

• DynamoDB Global Tables

• WAF and Shield

• Advanced monitoring (X-Ray)

• Reserved capacity

Common Pitfalls

• Over-engineering early - Don't build for 10M users with 100

• Public S3 buckets - Block public access

• Overly permissive IAM - Avoid * permissions

• No caching - Add CloudFront early

• NAT Gateway costs - Use VPC endpoints