AWS ‐ Regions | AZs - FullstackCodingGuy/Developer-Fundamentals GitHub Wiki
For SaaS applications, the most commonly used AWS regions are selected based on factors like low latency, high availability, compliance, and cost optimization. Below are the most popular AWS regions for SaaS deployments:
🔹 Best for: Compliance and SaaS growth in the Middle East & Africa.
✅ User Base Location → Choose a region closest to your users to reduce latency.
✅ Compliance Requirements → For GDPR, use eu-central-1 (Germany); for financial data, us-east-1 (Virginia).
✅ Cost Consideration → us-east-1 (Virginia) and us-west-2 (Oregon) are the cheapest.
✅ AWS Services Availability → New AWS services are first launched in us-east-1.
✅ Disaster Recovery (DR) → Use multiple regions (e.g., Primary: us-east-1, DR: us-west-2).
For an Active-Active or Active-Passive Multi-Region Setup, it's critical to segregate resources efficiently across Primary and Secondary regions to ensure:
✅ High Availability (No downtime during failures)
✅ Cost Optimization (Avoid unnecessary duplication of expensive resources)
✅ Low Latency & Performance Scaling
✅ Disaster Recovery & Failover Capabilities
| Service/Component | Primary Region (Active) | Secondary Region (Passive/Active) | Reasoning |
|---|---|---|---|
| Route 53 (DNS Routing) | ✅ Global | ✅ Global | Latency-Based or Failover Routing |
| CloudFront (CDN + Edge Locations) | ✅ Global | ✅ Global | Caches static content worldwide |
| Application Load Balancer (ALB) | ✅ Active | ✅ Standby (for failover) | Handles user requests across EC2/ECS |
| AWS Global Accelerator | ✅ Active | ✅ Active | Redirects traffic to the closest healthy region |
| EC2, ECS (Compute Services) | ✅ Fully Deployed | ✅ Auto-Scaled (or minimal standby) | Runs application services, can auto-scale |
| Lambda (Serverless Functions) | ✅ Active | ✅ Deployed (Cold Standby or Active) | Critical for microservices, must be replicated |
| RDS (Aurora Global Database) | ✅ Primary Writer Node | ✅ Read-Replica (or Failover Standby) | Multi-Region DB with automatic failover |
| DynamoDB (Global Tables) | ✅ Active | ✅ Active | Automatically synchronizes data across regions |
| S3 Buckets | ✅ Primary Storage | ✅ Cross-Region Replicated | Stores media, documents, logs with replication |
| Elasticache (Redis/Memcached) | ✅ Active | ✅ Standby (or rehydrated on failover) | Caches frequently used queries |
| SNS (Notifications & Alerts) | ✅ Active | ✅ Active | Global SNS topics for push notifications |
| SQS (Message Queues) | ✅ Active | ✅ Active | For async processing, should be global |
| MediaConvert (Video Processing) | ✅ Active | ❌ On-Demand Only | Expensive, should not run in standby |
| AWS Backup | ✅ Regular Backups | ✅ Cross-Region Backup Replication | Disaster Recovery Strategy |
| IAM Roles & Policies | ✅ Global | ✅ Global | Same IAM roles & permissions for both regions |
| GuardDuty / WAF / Shield | ✅ Global | ✅ Global | Security protections applied globally |
✔ Route 53 Latency-Based Routing → Sends traffic to the nearest region.
✔ DynamoDB Global Tables & Aurora Global → Both regions read/write seamlessly.
✔ CloudFront & Global Accelerator → Distributes traffic globally for lower latency.
✔ EC2/ECS/Lambda in Both Regions → Scaled evenly to avoid overloading one region.
✅ Benefits: No downtime, better performance, automatic scaling.
✔ Route 53 Failover Routing → Redirects traffic only if the Primary fails.
✔ Aurora Global (Read Replica in Secondary) → Promoted to Primary during failover.
✔ Minimal EC2/ECS in Secondary → Only small instances running, scaling up when needed.
✔ S3 Cross-Region Replication → Backup data available in Secondary region.
✔ SNS, SQS, API Gateway Deployed in Both Regions → Ensures async processing continues.
✅ Benefits: Lower costs compared to Active-Active.
- Set up Route 53 DNS Failover based on ALB health checks.
- If Primary region fails, it automatically directs traffic to Secondary region.
- Aurora automatically promotes a secondary region DB to primary if failure occurs.
- Use Auto Scaling Groups (EC2/ECS) in the Secondary Region to scale up when failover happens.
- Replicate S3, RDS, DynamoDB, and ElastiCache backups to another region for quick recovery.
graph TD;
A[User Request] -->|Route 53 - Latency-Based Routing| B1[Primary Region - us-east-1];
A[User Request] -->|Route 53 - Failover Backup| B2[Secondary Region - ap-southeast-1];
subgraph Primary Region - Active
B1 -->|CloudFront - CDN| C1[Edge Locations];
C1 -->|AWS Global Accelerator| D1[Application Load Balancer - ALB];
D1 -->|Traffic Distribution| E1[EC2/ECS/Lambda Services];
E1 -->|Read/Write| F1[Aurora Global Database - Primary];
E1 -->|Read/Write| G1[DynamoDB Global Table - Primary];
E1 -->|Media Processing| H1[AWS MediaConvert];
E1 -->|Cache| J1[ElastiCache];
end
subgraph Secondary Region - Passive
B2 -->|CloudFront - CDN| C2[Edge Locations];
C2 -->|AWS Global Accelerator| D2[Application Load Balancer - ALB];
D2 -->|Traffic Distribution| E2[EC2/ECS/Lambda - Standby];
E2 -->|Read Only| F2[Aurora Global Database - Replica];
E2 -->|Read Only| G2[DynamoDB Global Table - Replica];
E2 -->|Failover Ready| H2[AWS MediaConvert];
E2 -->|Failover Ready| J2[ElastiCache];
end
F1 -->|Replication| F2;
G1 -->|Replication| G2;
K1[S3 Bucket] -->|Cross-Region Replication| K2[S3 - Backup];
L1[AWS Backup] -->|Replication| L2[AWS Backup - Secondary];
E1 -->|SNS/SQS| M1[SNS Event Processing];
E2 -->|SNS/SQS| M2[SNS Event Processing];
✔ Use Active-Active if you have real-time global users (e.g., vloggers uploading videos).
✔ Use Active-Passive if failover is acceptable to reduce costs.
✔ Replicate only critical services (DB, API, Compute) in Secondary Region to save costs.
✔ Use CloudFront (CDN) & DynamoDB Global Tables to reduce cross-region traffic costs.
✔ Enable Auto Scaling in Secondary Region to prevent idle resource costs.
Would you like a Terraform or AWS CloudFormation template for setting up a multi-region travel SaaS? 🚀