Cross-Region/Cloud Disaster Recovery Project on AWS

Objective

To implement a highly available and disaster recovery-ready infrastructure across two AWS regions using Route 53 failover mechanisms. This solution ensures service availability in case of a regional outage.

Architecture Overview

• Primary Region (Active Region)
• Secondary Region (Passive Region for DR)
• Global Load Balancing with Route 53
• Replication of Databases and Storage
• Automated Failover Mechanisms

Technology Stack

• AWS Services:
  • Route 53 – DNS-based failover
  • EC2 – Compute instances
  • S3 – Data replication between regions
  • RDS Multi-AZ with Read Replica – Cross-region database failover
  • Application Load Balancer (ALB) – Traffic distribution
  • Auto Scaling Groups (ASG) – Auto scaling across regions
  • IAM – Role-based access control
  • CloudWatch & CloudTrail – Monitoring & logging
  • AWS Systems Manager (SSM) – Configuration management
  • AWS Lambda – Failover automation

Task Implementation Steps

Step 1: Setup Primary Region (Active)

1. VPC & Networking
   • Create a VPC (CIDR: 10.0.0.0/16)
   • Create Public and Private Subnets across two AZs
   • Configure Internet Gateway and NAT Gateway
2. Compute Setup
   • Deploy EC2 instances in Private Subnets
   • Attach Application Load Balancer (ALB) to distribute traffic
   • Configure Auto Scaling Group for automatic scaling
3. Database & Storage
   • Deploy Amazon RDS (Multi-AZ)
   • Enable Cross-region Read Replica for DR
   • Enable S3 Cross-Region Replication (CRR) for backup
4. Security & IAM
   • Define IAM roles and policies for access control
   • Implement Security Groups and NACLs for network security

Step 2: Setup Secondary Region (Passive - DR)

1. Mirror VPC & Subnets in another region
   • Replicate the same VPC configuration in a different region
   • Maintain identical security group and NACL rules
2. Deploy EC2 instances (optional: keep them in stopped state)
   • Deploy EC2 instances but keep them in stopped state (optional to save cost)
   • Set up Amazon RDS Read Replica in the secondary region
3. S3 & Backup Replication
   • Enable S3 Cross-Region Replication
   • Ensure AWS Backup covers both regions

Step 3: Route 53 Failover Configuration

• Create a Route 53 Hosted Zone
  • Add A Records pointing to ALB in both regions
  • Enable Health Checks on Primary Region’s ALB
• Configure Failover Routing
  • Primary Region Record (Active)
    • Associate with ALB in the primary region
    • Enable Health Check to monitor primary ALB
• Secondary Region Record (Passive) -
  • Associate with ALB in the secondary region
  • Associate with ALB in the secondary region

Step 4: Implement Automated Failover

1. AWS Lambda for Failover
   • Trigger an AWS Lambda function when Route 53 detects failure
   • Lambda switches traffic to secondary region ALB
   • Optionally, start stopped EC2 instances in the DR region
2. CloudWatch Alerts
   • Set up CloudWatch Alarms on:
     • EC2 health status
     • ALB response time
     • Database availability
   • Notify using SNS or Slack/Webhook in case of failure

Step 5: Testing & Validation

1. Simulate Failover
   • Manually stop EC2 instances in the primary region
   • Validate if Route 53 redirects traffic to the secondary region
   • Check logs & CloudWatch for alerts
2. Database Recovery Test
   • Stop primary RDS instance
   • Promote Read Replica to Primary
   • Update Route 53 records to point to the new DB
3. Rollback Plan
   • Restart the primary region and revert Route 53
   • Sync databases and files after recovery

Final Deliverables

• Terraform Infrastructure Code
• AWS Route 53 Configuration
• Failover Automation Lambda Script
• Monitoring & Alerting Dashboards
• Disaster Recovery Runbook

Conclusion

This AWS cross-region disaster recovery project ensures business continuity by using Route 53 failover, cross-region replication, and automated failover mechanisms. The solution is cost-efficient and scalable, providing a reliable failover plan in case of regional failures.

Next Steps

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