Cross-Cloud Migration of Enterprise Infrastructure-as-Code Platform
Migrated mission-critical Terraform Enterprise platform from AWS to Azure with zero downtime, implementing high availability architecture, private ExpressRoute connectivity, and integrated Azure AD authentication to support enterprise-scale infrastructure automation.
As organizations evolve their cloud strategies, platform infrastructure must evolve with them. This project executed a strategic migration of the client's Terraform Enterprise platform from AWS to Azure, aligning their Infrastructure-as-Code operations with their broader cloud consolidation initiative while improving resilience, security, and operational efficiency.
Zero
Downtime During Migration
100+
Terraform Workspaces Migrated
HA
High Availability Architecture
The Challenge
The client's Azure cloud adoption strategy required consolidating Infrastructure-as-Code operations onto Azure, creating a complex multi-faceted migration challenge:
- Zero-Downtime Requirement: Terraform Enterprise manages critical infrastructure deployments across the organization. Any service interruption would block all infrastructure changes, halting development teams worldwide
- Cross-Cloud Migration: Moving from AWS-native services (RDS, S3, ALB) to Azure equivalents (PostgreSQL, Blob Storage, Application Gateway) while maintaining feature parity and performance
- State File Preservation: Terraform state files contain sensitive infrastructure metadata and must be migrated without corruption or data loss. State corruption could make infrastructure unmanageable
- Authentication Integration: Integrate with corporate Azure AD and external SAML authentication provider while migrating existing users, teams, and RBAC permissions without disruption
- Hybrid Connectivity: Establish private ExpressRoute connectivity to on-premises datacenter for Terraform runs accessing internal systems, replacing AWS Direct Connect
- High Availability Design: Improve resilience over previous AWS deployment with multi-zone redundancy, automated backups, and disaster recovery capabilities
- Data Residency: Ensure all Terraform data, including state files and run logs, remain within Azure for compliance and data governance requirements
- Minimal User Disruption: Preserve all existing workspaces, variable sets, team permissions, and workflow integrations with transparent cutover to minimize impact on development teams
The migration needed meticulous planning and flawless execution, as any failure could disrupt infrastructure automation across the entire organization.
Solution: Parallel Deployment with Phased Cutover
Deployed new Terraform Enterprise instance on Azure in parallel with existing AWS deployment, performed comprehensive data migration and validation, then executed coordinated cutover with automated DNS failover to ensure seamless transition.
High Availability Architecture
Deployed across multiple Azure Availability Zones with Application Gateway load balancing, Azure PostgreSQL Flexible Server with geo-redundant backup, and Azure Blob Storage with zone-redundant replication for maximum resilience.
Private ExpressRoute Connectivity
Configured Azure ExpressRoute with private peering to on-premises datacenter, providing dedicated 10 Gbps private network path for Terraform runs accessing internal systems without internet transit.
Integrated Authentication
Integrated with Azure AD for team management and external SAML IdP for user authentication. Synchronized all existing users, teams, and RBAC policies from AWS deployment using TFE API automation.
Zero-Downtime Migration
Migrated all workspaces, state files, and configurations to Azure while AWS instance remained operational. DNS cutover completed in under 5 minutes with automated health checks and rollback capability.
Migration Execution Phases
The migration was executed across four distinct phases over 2 months, with comprehensive testing and validation at each stage.
Phase 1: Infrastructure Deployment (Week 1-3)
- Deployed Terraform Enterprise on Azure VMs (Active-Standby cluster)
- Configured Azure PostgreSQL Flexible Server with private endpoint
- Set up Azure Blob Storage with zone-redundant replication
- Deployed Application Gateway with WAF and SSL termination
- Configured ExpressRoute connectivity to on-premises datacenter
- Implemented Azure Monitor, Log Analytics, and alerting
Phase 2: Authentication & Testing (Week 3-4)
- Integrated Azure AD for team/group synchronization
- Configured SAML SSO with external identity provider
- Migrated test workspaces and validated Terraform runs
- Tested ExpressRoute connectivity to on-prem resources
- Validated backup and restore procedures
- Performance testing and optimization
Phase 3: Data Migration (Week 5-7)
- Exported all workspaces, state files, and configurations from AWS TFE
- Migrated 100+ workspaces using TFE API automation scripts
- Validated state file integrity with checksum verification
- Migrated variable sets, SSH keys, and API tokens
- Synchronized team memberships and RBAC permissions
- Parallel validation testing on both platforms
Phase 4: Cutover & Validation (Week 8)
- Final delta sync of workspace changes from AWS to Azure
- Coordinated communication to all Terraform users
- Executed DNS cutover with automated health checks
- Monitored system performance and user activity
- Maintained AWS instance in read-only mode for 2 weeks rollback capability
- Decommissioned AWS infrastructure after validation period
Azure Architecture Components
Compute & Application Tier
- Azure VMs (D-series) in Active-Standby configuration
- Application Gateway with WAF v2
- Azure Availability Zones deployment
- Automated VM scaling and failover
- TLS 1.2+ with Azure-managed certificates
Data & Storage Tier
- Azure PostgreSQL Flexible Server
- Geo-redundant backups (35-day retention)
- Azure Blob Storage (ZRS replication)
- Private Endpoints for all data services
- Encryption at rest with CMK option
Security & Networking Tier
- Azure ExpressRoute private peering
- Network Security Groups (NSGs)
- Azure AD integration
- SAML SSO with external IdP
- Azure Monitor and Log Analytics
Technical Implementation Highlights
High Availability Design
The Azure deployment improved on the previous AWS architecture with true multi-zone redundancy:
- Active-Standby VMs: Primary and standby VMs deployed across different Availability Zones with automated health checks and failover
- Zone-Redundant Storage: Both PostgreSQL and Blob Storage use ZRS to survive complete zone failures
- Application Gateway: Deployed across zones with health probes and automatic backend failover
- RPO/RTO: Recovery Point Objective of 5 minutes (continuous PostgreSQL replication) and Recovery Time Objective of 15 minutes (automated failover)
Technology Stack
Terraform Enterprise Azure VMs Application Gateway PostgreSQL Flexible Server Azure Blob Storage ExpressRoute Azure AD SAML SSO Azure MonitorProject Information
- Client: [Protected by NDA]
- Project Date: August 2023
- Duration: 2 months
- Role: Cloud Infrastructure Engineer
Migration Outcomes
- Zero service interruption
- 100% workspace migration success
- No state file corruption
- Improved HA/DR capabilities
- 35% cost reduction vs AWS
- Consolidated cloud footprint
Results & Business Impact
Seamless Cutover
Executed cutover during business hours with zero downtime. Users experienced transparent transition with no manual reconfiguration required. DNS failover completed in under 5 minutes with no failed Terraform runs.
Enhanced Resilience
New architecture provides 99.9% SLA with automated failover, geo-redundant backups, and zone-redundant storage. Disaster recovery capability improved from 4 hours to 15 minutes RTO.
Cost Optimization
Achieved 35% cost reduction compared to AWS deployment through Azure Reserved Instances, right-sized PostgreSQL tier, and elimination of cross-cloud data transfer costs for Azure-based Terraform operations.
Key Takeaways
Parallel Deployment Eliminates Migration Risk
Running both platforms in parallel with gradual workspace migration allowed comprehensive validation before cutover. The ability to roll back to AWS instantly (via DNS) provided crucial safety net that made aggressive cutover timeline possible.
API Automation is Essential at Scale
Manually migrating 100+ workspaces would have taken weeks and introduced human error. Custom Python scripts using Terraform Enterprise API automated the entire migration process, completing workspace migration in hours with perfect fidelity.
ExpressRoute Setup Takes Longer Than Expected
Private ExpressRoute peering requires coordination with network teams, circuit provisioning, BGP configuration, and routing validation. Started ExpressRoute setup in Week 1 to ensure connectivity was ready for testing by Week 3 - this lead time was necessary.
Communication Prevents User Confusion
Proactive communication with development teams about migration timeline, what to expect, and how to report issues was crucial. Created dedicated Slack channel for migration updates and support, preventing confusion during cutover window.
Zone-Redundancy Improves Resilience Without Complexity
Azure Availability Zones provide better failure isolation than AWS Availability Zones due to physically separated datacenters. Deploying across zones with ZRS storage and zone-redundant PostgreSQL dramatically improved resilience with minimal architectural complexity - no manual replication or complex failover logic required.