Advanced

Multi-Region Active-Active

Build a globally distributed application with automatic failover

Project Overview

Design and deploy an application that runs simultaneously in multiple AWS regions, providing low latency for global users and resilience against regional failures.

Difficulty: Advanced

AWS Services: Route 53, Global Accelerator, Aurora Global, DynamoDB Global Tables

Cost: ~$200-500/month (tear down after learning)

Prerequisites

Completed Three-Tier Web Application project
Strong understanding of VPC networking
Experience with RDS or DynamoDB
Infrastructure as Code skills

Architecture

🌐

Global Users

↓

🌍

Global Accelerator

Anycast IP

↓

Region A (us-east-1)

🖥

App Stack

🗃

DynamoDB

↔

Replication

Region B (eu-west-1)

🖥

App Stack

🗃

DynamoDB

Global Tables provide automatic bi-directional replication

Step-by-Step Instructions

Deploy Application in Primary Region

Deploy your three-tier application in us-east-1
Use Infrastructure as Code for reproducibility
Ensure all resources are tagged for cost tracking
Document all configurations and dependencies

Set Up DynamoDB Global Tables

Convert your DynamoDB table to a Global Table
Add replica in secondary region (e.g., eu-west-1)
Understand eventual consistency implications
Plan for conflict resolution (last writer wins)
Monitor replication lag with CloudWatch

Deploy Application in Secondary Region

Run same IaC template in eu-west-1
Update configuration to use local DynamoDB replica
Ensure identical AMIs or container images
Verify application functions independently

Configure Global Traffic Management

Option A: Create AWS Global Accelerator
Option B: Use Route 53 latency-based routing
Add endpoints from both regions
Configure health checks for automatic failover
Set appropriate TTLs for DNS records

Implement Health Checks and Failover

Create Route 53 health checks for each region
Configure CloudWatch alarms for health metrics
Set up SNS notifications for failover events
Define recovery procedures and runbooks

Test Failover Scenarios

Simulate regional failure by stopping services
Verify traffic automatically routes to healthy region
Test data consistency after failover
Measure Recovery Time Objective (RTO)
Document findings and optimize

Tips

Use eventual consistency patterns - Design your application to handle temporary data inconsistencies
Monitor replication lag - Set up CloudWatch alarms for Global Tables replication metrics
Test regularly - Run game days to practice failover procedures
Consider data locality regulations - Some data may need to stay in specific regions

Code Examples

DynamoDB Global Tables Setup

Terminal Commands BASH

# Create DynamoDB table with Global Tables v2
aws dynamodb create-table \
    --table-name UserSessions \
    --attribute-definitions AttributeName=userId,AttributeType=S \
    --key-schema AttributeName=userId,KeyType=HASH \
    --billing-mode PAY_PER_REQUEST \
    --stream-specification StreamEnabled=true,StreamViewType=NEW_AND_OLD_IMAGES \
    --region us-east-1

# Add replica in eu-west-1
aws dynamodb update-table \
    --table-name UserSessions \
    --replica-updates "Create={RegionName=eu-west-1}" \
    --region us-east-1

Route 53 Latency-Based Routing

route53-latency.json JSON

{
    "Changes": [
        {
            "Action": "CREATE",
            "ResourceRecordSet": {
                "Name": "app.example.com",
                "Type": "A",
                "SetIdentifier": "us-east-1",
                "Region": "us-east-1",
                "AliasTarget": {
                    "HostedZoneId": "Z35SXDOTRQ7X7K",
                    "DNSName": "us-east-1-alb.example.com",
                    "EvaluateTargetHealth": true
                }
            }
        },
        {
            "Action": "CREATE",
            "ResourceRecordSet": {
                "Name": "app.example.com",
                "Type": "A",
                "SetIdentifier": "eu-west-1",
                "Region": "eu-west-1",
                "AliasTarget": {
                    "HostedZoneId": "Z32O12XQLNTSW2",
                    "DNSName": "eu-west-1-alb.example.com",
                    "EvaluateTargetHealth": true
                }
            }
        }
    ]
}

Global Accelerator CloudFormation

global-accelerator.yaml YAML

AWSTemplateFormatVersion: '2010-09-09'
Resources:
  GlobalAccelerator:
    Type: AWS::GlobalAccelerator::Accelerator
    Properties:
      Name: multi-region-accelerator
      Enabled: true
      IpAddressType: IPV4

  Listener:
    Type: AWS::GlobalAccelerator::Listener
    Properties:
      AcceleratorArn: !Ref GlobalAccelerator
      Protocol: TCP
      PortRanges:
        - FromPort: 443
          ToPort: 443

  EndpointGroup1:
    Type: AWS::GlobalAccelerator::EndpointGroup
    Properties:
      ListenerArn: !Ref Listener
      EndpointGroupRegion: us-east-1
      TrafficDialPercentage: 50
      HealthCheckProtocol: HTTPS
      EndpointConfigurations:
        - EndpointId: !Ref USEastALB
          Weight: 100

  EndpointGroup2:
    Type: AWS::GlobalAccelerator::EndpointGroup
    Properties:
      ListenerArn: !Ref Listener
      EndpointGroupRegion: eu-west-1
      TrafficDialPercentage: 50
      EndpointConfigurations:
        - EndpointId: !Ref EUWestALB
          Weight: 100

Health Check with Route 53

Terminal Commands BASH

# Create health check for primary region
aws route53 create-health-check --caller-reference $(date +%s) \
    --health-check-config '{
        "IPAddress": "1.2.3.4",
        "Port": 443,
        "Type": "HTTPS",
        "ResourcePath": "/health",
        "FullyQualifiedDomainName": "us-east-1-alb.example.com",
        "RequestInterval": 10,
        "FailureThreshold": 3
    }'

# List health checks
aws route53 list-health-checks

What You'll Learn

Multi-region architecture design patterns
Global traffic management with Route 53 and Global Accelerator
Data replication strategies and consistency models
Conflict resolution patterns for distributed writes
Failover automation and disaster recovery testing