🚧 DRAFT PR - DO NOT MERGE UNTIL DRAFT STATUS HAS BEEN REMOVED AS WELL AS THIS LINE 🚧
Issue number:
#713

Summary

This PR implements Major DDC Module Architecture Consolidation that eliminates circular dependencies, implements robust cleanup mechanisms, and establishes the gold standard for all CGD Toolkit modules. The fragmented infrastructure/applications split has been replaced with a unified, production-ready conditional submodule architecture.

Problem Statement

Previous Architecture

The DDC module was split across separate infrastructure/ and applications/ modules, which presented some architectural challenges:

modules/
├── infrastructure/     # EKS + nodes + ScyllaDB + S3 (deployed first)
└── applications/       # EKS addons + Helm + references NLBs (deployed second)

Areas for Improvement:

1. Circular Dependencies: Applications module created AWS infrastructure (NLBs via Load Balancer Controller) that it then tried to reference in the same module
2. Cross-Module Resource Creation: Applications module shouldn't create AWS infrastructure
3. Unpredictable Timing: When does the NLB get created vs referenced?
4. Destroy Order Issues: Which module destroys the NLB? Frequent orphaned resources
5. Multi-Region Complexity: Complex cross-region deployment coordination
6. IP Access Dependencies: Destroy operations failed when user IP changed since deployment

User Impact

• Occasional destroy failures with orphaned ENIs and Load Balancers
• Deployment timing dependencies that could be simplified
• Multi-region setup requiring manual coordination
• Error messages that could be more helpful

Solution Overview

New Consolidated Architecture

Following the successful Perforce module pattern, implemented conditional submodule architecture:

modules/unreal-cloud-ddc/
├── main.tf                    # Conditional submodule orchestration
├── modules/
│   ├── ddc-infra/            # Infrastructure: EKS + ScyllaDB + NLB + Kubernetes
│   ├── ddc-monitoring/       # Monitoring: ScyllaDB monitoring + ALB
│   └── ddc-services/         # Services: Helm charts only (no AWS resources)
└── assets/
    ├── media/diagrams/       # Architecture documentation
    └── submodules/           # Submodule-specific assets
        ├── ddc-infra/
        ├── ddc-monitoring/
        └── ddc-services/

Key Architectural Principles

1. Conditional Submodules: count = var.config != null ? 1 : 0 pattern
2. Deterministic Infrastructure: All AWS resources created via Terraform
3. Clean Separation: Infrastructure vs Applications vs Monitoring
4. Multi-Region Ready: Multiple parent module instances approach
5. User Choice: Flexible deployment patterns (infrastructure-only, full-stack, etc.)

Major Changes

1. Eliminated Circular Dependencies

Before:

# applications module creating AND referencing NLB
enable_aws_load_balancer_controller = true  # Creates NLB
data "aws_lb" "ddc_nlb" {
  depends_on = [helm_release.ddc]  # Circular dependency!
}

After:

# ddc-infra creates deterministic NLB
resource "aws_lb" "ddc_nlb" {
  name_prefix = "${var.project_prefix}-"
  # ... predictable configuration
}

# ddc-services uses ClusterIP + target group annotation
service:
  type: ClusterIP
  annotations:
    service.beta.kubernetes.io/aws-load-balancer-target-group-arn: ${target_group_arn}

2. Implemented Conditional Submodule Pattern

# Users can deploy only what they need
module "ddc_infra" {
  source = "./modules/ddc-infra"
  count  = var.ddc_infra_config != null ? 1 : 0
}

module "ddc_monitoring" {
  source = "./modules/ddc-monitoring"
  count  = var.ddc_monitoring_config != null ? 1 : 0
}

module "ddc_services" {
  source = "./modules/ddc-services"
  count  = var.ddc_services_config != null ? 1 : 0
}

3. Enhanced Multi-Region Support

Before: Complex internal multi-region logic with provider aliases
After: Multiple parent module instances (one per region)

# Primary region
module "ddc_primary" {
  source = "../../"
  ddc_infra_config = {
    region = "us-east-1"
    is_primary_region = true
  }
}

# Secondary region
module "ddc_secondary" {
  source = "../../"
  ddc_infra_config = {
    region = "us-west-2"
    is_primary_region = false
    existing_scylla_seed = module.ddc_primary.scylla_seed_ip
  }
}

4. Robust Cleanup & Destroy Safety

Added automatic Helm cleanup with comprehensive error handling:

# Configurable cleanup behavior
ddc_services_config = {
  auto_cleanup = true  # Default: automatic cleanup
  # auto_cleanup = false  # Manual cleanup for advanced users
}

Enhanced error messages with troubleshooting guidance:

• IP access validation with specific remediation steps
• Links to documentation sections
• Clear explanation of destroy dependencies
• Configurable timeouts for different environments

5. Improved Asset Organization & Examples Enhancement

Before: File placement that could be more consistent
After: Standardized structure with clear separation:

assets/
├── media/diagrams/           # Architecture diagrams
└── submodules/              # Clear submodule boundary
    ├── ddc-infra/          # Infrastructure-specific assets
    ├── ddc-monitoring/     # Monitoring-specific assets
    └── ddc-services/       # Service-specific assets
        ├── unreal_cloud_ddc_consolidated.yaml    # Single chart for all deployments
        ├── unreal_cloud_ddc_single_region.yaml  # Backup/legacy
        └── unreal_cloud_ddc_multi_region.yaml   # Backup/legacy

examples/                    # User-facing tutorials (moved from samples/)
├── single-region/          # Complete working example
└── multi-region/           # Multi-region deployment pattern

Samples → Examples Enhancement:

• Moved from "samples" to "examples" for clarity
• Enhanced with complete, working tutorials
• Added comprehensive documentation with step-by-step instructions
• Provided tested configurations that users can copy and modify

Benefits

For Users

1. Reliable Destroys: No more orphaned resources or IP access issues
2. Flexible Deployment: Deploy only needed components (infra-only, monitoring, services)
3. Better Error Messages: Clear troubleshooting guidance with documentation links
4. Multi-Region Simplified: Clean two-instance pattern vs complex internal logic
5. User Choice: Automatic vs manual cleanup based on preferences

For Developers

1. Clean Architecture: Clear module boundaries and dependencies
2. Maintainable Code: Standardized structure following established patterns
3. Testable Components: Each submodule can be tested independently
4. Extensible Design: Easy to add new components or regions

For Operations

1. Predictable Infrastructure: All AWS resources created deterministically
2. Cost Control: Skip expensive components in secondary regions
3. Staged Rollouts: Deploy infrastructure first, applications later
4. Clear Dependencies: Explicit dependency flow and coordination

Usage Examples

Infrastructure Only

module "ddc" {
  source = "path/to/module"
  
  ddc_infra_config = {
    # EKS + ScyllaDB + NLB configuration
  }
  # No monitoring or services - just infrastructure
}

Full Stack Single Region

module "ddc" {
  source = "path/to/module"
  
  ddc_infra_config = { /* ... */ }
  ddc_monitoring_config = { /* ... */ }
  ddc_services_config = { 
    auto_cleanup = true  # Automatic Helm cleanup
  }
}

Multi-Region Deployment

# Primary region
module "ddc_primary" {
  source = "path/to/module"
  ddc_infra_config = { is_primary_region = true }
  ddc_monitoring_config = { /* ... */ }
  ddc_services_config = { /* ... */ }
}

# Secondary region
module "ddc_secondary" {
  source = "path/to/module"
  ddc_infra_config = { 
    is_primary_region = false
    existing_scylla_seed = module.ddc_primary.scylla_seed_ip
  }
  ddc_services_config = {
    ddc_replication_region_url = module.ddc_primary.nlb_dns_name
  }
  # No monitoring in secondary region (cost optimization)
}

Documentation Enhancements

Comprehensive README Overhaul

• Architecture Deep-Dive: ScyllaDB node mapping, EKS integration, service types
• Troubleshooting Guide: Covers creation, update, connection, and deletion issues
• FAQ Section: Design decisions, technology choices, operational questions
• Multi-Region Patterns: Deployment strategies and coordination mechanisms

Gold Standard Module Structure

Created HOW_TO_CONTRIBUTE.md establishing standards for all CGD Toolkit modules:

• Directory Structure: Simple vs complex module patterns
• File Naming Conventions: Consistent across all modules
• Documentation Quality: Comprehensive guidelines and review processes
• Design Principles: When to use submodules, asset organization, etc.

Enhanced User Experience

• Audience-Specific Callouts: Clear visual indicators for DevOps vs Game Developers
• Streamlined Navigation: Direct GitHub links for examples to preserve documentation flow
• Improved Code Organization: Separate code blocks for better copy-paste experience
• Terraform Output Integration: Commands use terraform output for actual values
• Security Best Practices: Clear distinction between infrastructure and application access
• Progressive Disclosure: Basic → Advanced configuration patterns

Documentation Quality Improvements

• Removed Outdated Content: Eliminated incorrect provider configuration and migration examples
• Fixed Inaccuracies: Updated all code snippets to match actual module structure
• Enhanced Troubleshooting: Comprehensive IP access requirements and destroy procedures
• Clear Prerequisites: Epic Games organization access and GitHub credential setup
• Multi-Region Clarity: Simplified deployment patterns with working examplesConditional Deployment Messages: Optional user feedback during operations
• Comprehensive Examples: Infrastructure-only, full-stack, multi-region patterns
• Clear Configuration: Well-documented variables with validation and examples

Breaking Changes

Variable Structure Changes

Before:

# Separate modules with complex configuration
module "infrastructure" { /* ... */ }
module "applications" { /* ... */ }

After:

# Unified module with conditional submodules
module "ddc" {
  ddc_infra_config = { /* ... */ }      # Optional
  ddc_monitoring_config = { /* ... */ }  # Optional  
  ddc_services_config = { /* ... */ }    # Optional
}

Migration Path

1. Update variable structure to use new conditional config objects
2. Remove separate module calls - use single unified module
3. Update multi-region deployments to use multiple parent instances
4. Review cleanup configuration - set auto_cleanup preference

Testing

Validated Deployment Patterns

• ✅ Infrastructure Only: EKS + ScyllaDB + NLB creation
• ✅ Full Stack Single Region: All components working together
• ✅ Multi-Region: Cross-region coordination and replication
• ✅ Conditional Logic: Proper submodule creation/skipping
• ✅ Cleanup Mechanisms: Both automatic and manual cleanup paths

Regression Testing

• ✅ No Circular Dependencies: Clean dependency graph
• ✅ Deterministic Destroys: Reliable cleanup without orphaned resources
• ✅ Multi-Region Coordination: ScyllaDB cross-region replication
• ✅ Error Handling: Comprehensive error scenarios covered

Future Enhancements

Planned Improvements

1. Amazon Keyspaces Support: Alternative to self-managed ScyllaDB
2. Existing EKS Cluster Support: Deploy to existing clusters
3. Additional Regions: Easy expansion beyond two regions
4. Enhanced Monitoring: Cross-region monitoring consolidation

Extensibility

The new architecture makes these enhancements straightforward:

• New submodules can be added easily
• Additional deployment patterns supported via conditional logic
• Cross-region features simplified with multiple instance pattern

Conclusion

This refactor transforms the DDC module from a fragmented, unreliable architecture into a production-ready, enterprise-grade solution. By eliminating circular dependencies, implementing robust cleanup mechanisms, and establishing comprehensive documentation standards, the module now serves as the gold standard for all CGD Toolkit modules.

Key Achievements:

• ✅ Eliminated circular dependencies and destroy issues
• ✅ Implemented flexible deployment patterns following Perforce module success
• ✅ Enhanced multi-region support with clean coordination mechanisms
• ✅ Established documentation gold standard for entire toolkit
• ✅ Improved user experience with better error handling and guidance
• ✅ Created maintainable architecture for long-term sustainability

The module is now production-ready and provides a solid foundation for game development teams deploying Unreal Cloud DDC infrastructure on AWS.