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Multi-Cloud Connectivity: AWS ↔ Azure

Break down cloud silos and unlock the power of multi-cloud architecture. Our Terraform module creates secure, seamless connectivity between your AWS and Azure environments, enabling true hybrid cloud applications.

Why Multi-Cloud?​

🌐 Best of Both Worlds - Use AWS services where they excel and Azure services where they shine
🔄 Avoid Vendor Lock-in - Maintain flexibility and negotiating power with cloud providers
🛡️ Enhanced Resilience - Distribute workloads across multiple cloud providers for ultimate reliability
📈 Strategic Flexibility - Adapt to changing business needs, acquisitions, or compliance requirements
💰 Cost Optimization - Leverage competitive pricing and specialized services from both clouds

What You Get​

✅ Unified Network - Your AWS and Azure resources communicate as if on the same network
✅ Cross-Cloud DNS - Resolve private hostnames seamlessly across both clouds
✅ Zero Configuration Routing - Automatic route management between environments
✅ Enterprise Security - Encrypted IPSec tunnels with BGP routing
✅ High Availability Options - Redundant connections for mission-critical workloads

Multi-Cloud Use Cases​

🚀 Hybrid Applications​

Run your frontend on Azure App Service while leveraging AWS Lambda for serverless compute, or use Azure AI services with data stored in AWS S3.

🔄 Cloud Migration & Modernization​

Gradually migrate workloads between clouds without disrupting operations:

  • Phase 1: Establish connectivity between existing AWS infrastructure and new Azure services
  • Phase 2: Migrate services incrementally while maintaining integration
  • Phase 3: Optimize workload placement based on performance and cost

🛡️ Disaster Recovery & Business Continuity​

  • Primary: Run production workloads on AWS
  • Secondary: Maintain hot standby on Azure with real-time data replication
  • Failover: Seamlessly switch to Azure during AWS outages

📊 Data & Analytics Pipelines​

  • Collect data in AWS S3 and process it with Azure Synapse Analytics
  • Use AWS Redshift for data warehousing and Azure Power BI for visualization
  • Leverage Azure Cognitive Services with data stored in AWS

Multi-Cloud Architecture​

How It Works​

The module creates secure IPSec tunnels between your AWS VPC and Azure Virtual Network, establishing a private "bridge" between clouds:

Development Configuration​

Single VPN Connection - Perfect for:

  • Development and testing environments
  • Proof of concepts and prototypes
  • Small-scale multi-cloud applications
  • Cost-conscious implementations

High Availability Configuration​

Redundant VPN Connections - Essential for:

  • Production multi-cloud applications
  • Mission-critical workloads
  • Enterprise disaster recovery
  • 24/7 business operations

Building Your Multi-Cloud Infrastructure​

Step 1: Multi-Cloud Prerequisites​

✅ AWS Environment Ready

  • VPC with private subnets and route tables
  • NAT Gateway configured (nat_gateway_count ≥ 1 for development)
  • Appropriate IAM permissions for VPN resources

✅ Azure Environment Ready

  • Virtual Network with Gateway Subnet (minimum /27 size)
  • Resource group for network resources
  • Appropriate RBAC permissions

✅ Network Planning

  • Non-overlapping CIDR blocks between AWS and Azure
  • DNS zone strategy for cross-cloud resolution
  • Security group and NSG rules for inter-cloud traffic
** Ensure your AWS VPC and Azure VNet CIDRs do not overlap

For example, an AWS VPC with 10.0.0.0/16 as a CIDR doesn't overlap with your Azure VNet CIDR 10.1.0.0/16.

This is critical for routing to work correctly.

Use tools to compute non overlapping CIDRs.

Step 2: Choose Your Implementation Path​

For Development & Testing:

For Production & Enterprise:

Step 3: Deploy with Terraform​

# 1. Clone the examples
git clone https://github.com/pagopa/dx.git
cd dx/infra/modules/aws_azure_vpn/examples/development

# 2. Configure your variables
cp terraform.tfvars.example terraform.tfvars
# Edit terraform.tfvars with your AWS/Azure details

# 3. Deploy your multi-cloud connectivity
terraform init
terraform plan
terraform apply

Step 4: Validate Multi-Cloud Connectivity​

After deployment, verify your setup:

  • ✅ Check VPN tunnel status in both AWS and Azure consoles
  • ✅ Test cross-cloud ping between resources
  • ✅ Verify DNS resolution across clouds
  • ✅ Monitor tunnel health and performance

Getting Started​

Ready to implement multi-cloud connectivity? Choose your path:

📚 Complete Documentation - Detailed module documentation

⚙️ Configuration Examples - Ready-to-use Terraform configurations

📦 Terraform Registry - Official module registry page

Multi-Cloud Troubleshooting​

"Cross-cloud communication isn't working"​

Multi-cloud specific checks:

  1. Network Isolation: Verify CIDR blocks don't overlap between AWS (e.g., 10.0.0.0/16) and Azure (e.g., 10.1.0.0/16)
  2. Security Boundaries: Check security groups (AWS) and NSGs (Azure) allow cross-cloud traffic
  3. VPN Status: Confirm tunnels are established in both AWS and Azure consoles
  4. Wait Period: Multi-cloud connections take 15-20 minutes to fully establish

"DNS resolution across clouds failing"​

Cross-cloud DNS troubleshooting:

  1. Zone Configuration: Ensure DNS zones are correctly specified for both clouds
  2. Forwarder Connectivity: Verify Azure DNS forwarder IP is reachable from AWS
  3. Resolution Test: Try resolving by IP first, then by hostname
  4. Propagation Time: DNS changes can take several minutes to propagate across clouds

"High availability not working in multi-cloud setup"​

Enterprise multi-cloud checks:

  1. Gateway Capacity: Ensure Azure VPN Gateway supports active-active mode
  2. IP Allocation: Verify sufficient public IP addresses are available
  3. Tunnel Health: Check that all VPN tunnels show "Connected" status
  4. Load Distribution: Confirm traffic is properly distributed across tunnels

Validating Your Multi-Cloud Setup​

After deployment, test your multi-cloud connectivity:

1. Network Connectivity Test​

# From AWS EC2 instance, ping Azure VM private IP
ping 10.1.1.100

# From Azure VM, ping AWS EC2 private IP
ping 10.0.1.100

2. Cross-Cloud DNS Test​

# Resolve Azure private DNS from AWS
nslookup myapp.azure.internal

# Resolve AWS private DNS from Azure
nslookup myapp.aws.internal

3. Application Integration Test​

  • Deploy a simple application spanning both clouds
  • Test database connections across clouds
  • Verify API calls between AWS and Azure services

Multi-Cloud Best Practices​

🏗️ Architecture Patterns​

  • Microservices: Deploy services on the cloud that best fits their requirements
  • Data Locality: Keep data close to processing to minimize latency
  • Failure Domains: Distribute critical components across clouds for resilience

🔒 Security Considerations​

  • Network Segmentation: Use separate subnets for cross-cloud communication
  • Encryption: All traffic flows through encrypted IPSec tunnels
  • Access Control: Implement strict IAM/RBAC policies on both clouds

📊 Monitoring & Observability​

  • Monitor VPN tunnel health on both AWS and Azure
  • Set up alerts for connection failures
  • Track cross-cloud traffic patterns and costs
  • Use distributed tracing for multi-cloud applications

What's Next in Your Multi-Cloud Journey?​

After your VPN connection is established:

  1. Test connectivity - Try pinging between your AWS and Azure resources using private IPs
  2. Design Multi-Cloud Applications - Plan your architecture to leverage the best of both clouds
  3. Implement Cross-Cloud Data Sync - Set up data replication strategies
  4. Build Multi-Cloud CI/CD - Deploy to both clouds from a single pipeline
  5. Monitor Multi-Cloud Performance - Track latency, costs, and reliability across clouds
  6. Scale Globally - Expand to additional regions in both AWS and Azure

Learn More​

📚 Documentation & Resources:

🛠️ Get Support:

Ready to break down cloud barriers and build the future of multi-cloud applications? Start with our development example and unlock the power of AWS + Azure today! 🚀