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

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