DRAFT - NOT YET APPROVED

ADR-007: Cloud Infrastructure Strategy for FlowMart E-commerce Platform

Status

Draft (Last Updated: 2024-09-25)

Context

As part of our transition to a microservices architecture, we need to define our cloud infrastructure strategy to support the new FlowMart e-commerce platform. Our current infrastructure consists primarily of on-premises data centers with some workloads in AWS, creating operational and scaling challenges:

1. Infrastructure Provisioning: Manual processes for provisioning infrastructure lead to long lead times for new environments and services.

2. Scaling Limitations: Physical hardware constraints prevent rapid scaling during peak shopping periods.

3. High Operational Overhead: Significant effort required for hardware maintenance, patching, and capacity management.

4. Disaster Recovery Challenges: Limited geographic redundancy and complex DR procedures.

5. Cloud Fragmentation: Ad-hoc adoption of cloud services has created inconsistent practices and tooling.

6. Developer Experience: Complex local development setup and environment inconsistencies slow down development cycles.

7. Cost Management: Difficult to attribute infrastructure costs to specific business capabilities or teams.

8. Security Compliance: Maintaining compliance across hybrid infrastructure requires duplicate controls and auditing.

We need a cohesive infrastructure strategy that enables rapid delivery, scalability, and operational efficiency for our new e-commerce platform.

Decision

We will adopt a cloud-native infrastructure strategy with a multi-cloud capability but AWS-primary approach. Key aspects of this strategy include:

1. Primary Cloud Platform:

   • AWS will be our primary cloud provider for all new workloads
   • Azure will be maintained as a secondary provider for specific use cases (e.g., Microsoft-ecosystem services)
   • GCP may be selectively used for specialized AI/ML workloads

2. Infrastructure as Code (IaC):

   • Terraform as primary IaC tool for provisioning cloud resources
   • AWS CDK for complex, AWS-specific resource configurations
   • GitOps-based deployment workflows with infrastructure CI/CD pipelines

3. Containerization Strategy:

   • Containerize all new microservices using Docker
   • Amazon EKS (Kubernetes) as primary container orchestration platform
   • Amazon ECR for container registry with cross-region replication

4. Platform Services Over Custom Infrastructure:

   • Prefer managed services over self-managed infrastructure where possible
   • AWS RDS, DocumentDB, ElastiCache for database needs
   • AWS MSK (Managed Kafka) for event streaming
   • CloudFront for CDN and edge caching

5. Multi-Region Architecture:

   • Primary operations in AWS US-East-1 and US-West-2
   • Active-active configuration for critical services
   • Region-specific deployments for EU and APAC markets to address data residency

6. Landing Zone and Account Structure:

   • Hub-and-spoke model with centralized security and governance
   • Separate AWS accounts for production, staging, development, and sandbox environments
   • Service-oriented account structure within each environment category
   • Centralized logging, monitoring, and security controls

7. Network Architecture:

   • Transit Gateway for interconnecting VPCs and on-premises
   • VPC design aligned with microservice domains
   • AWS PrivateLink for service-to-service connectivity
   • AWS Shield and WAF for DDoS protection and application security

8. Cost Optimization:

   • Tagging strategy for cost allocation and tracking
   • Automated cost monitoring and anomaly detection
   • Leverage Savings Plans and Reserved Instances strategically
   • Implemented auto-scaling for elastic workloads

Infrastructure Architecture by Domain

Domain	Primary Services	Scaling Strategy	Special Requirements
Product Catalog	EKS, ElastiCache, DocumentDB	Horizontal pod scaling, Read replicas	High read throughput, Global availability
Order Processing	EKS, RDS (PostgreSQL), MSK	Horizontal pod scaling, DB connection pooling	Strong consistency, Transaction support
Payment	EKS, RDS (PostgreSQL), KMS	Fixed scaling with headroom	PCI-DSS compliance, Encryption requirements
Inventory	EKS, DocumentDB, Lambda	Horizontal auto-scaling	Event-sourcing patterns, Eventual consistency
User Authentication	Cognito, Lambda, DynamoDB	Regional deployments	Multi-factor auth, Token management
Content Delivery	S3, CloudFront, Lambda@Edge	Edge caching, Regional replication	Image optimization, Low latency delivery
Search	OpenSearch, Lambda, EKS	Search domain scaling, Query throttling	High cardinality, Complex query support
Analytics	Redshift, Kinesis, EMR	Workload-based scaling	Batch processing, Data lake integration

Consequences

Positive

1. Improved Scalability: Elastic infrastructure that scales with demand without manual intervention.

2. Faster Time-to-Market: Automated provisioning and deployment enable rapid delivery of new features.

3. Enhanced Resilience: Multi-region architecture improves availability and disaster recovery capabilities.

4. Cost Efficiency: Pay-for-use model and automated scaling optimize infrastructure costs.

5. Developer Productivity: Consistent environments and self-service capabilities improve developer experience.

6. Security Improvements: Standardized security controls and automated compliance checks.

7. Operational Efficiency: Reduced operational overhead through managed services and automation.

8. Global Reach: Ability to deploy services closer to customers in different geographic regions.

Negative

1. Cloud Vendor Dependency: While designed for multi-cloud, primary workloads will have AWS dependencies.

2. Cost Management Complexity: Cloud costs can escalate without proper governance and monitoring.

3. Skill Set Transition: Team needs to develop new skills in cloud-native technologies and practices.

4. Increased Architectural Complexity: Distributed cloud architecture is more complex to design and troubleshoot.

5. Security Model Changes: Cloud security requires different approaches and tools than on-premises.

6. Data Transfer Costs: Cross-region and internet data transfer can become a significant cost factor.

7. Service Maturity Variations: Some AWS services are more mature and reliable than others.

Mitigation Strategies

1. Cloud Platform Team:

   • Create a dedicated platform engineering team for cloud infrastructure
   • Develop reusable infrastructure modules and patterns
   • Provide internal consultation and support to service teams

2. Cloud Center of Excellence (CCoE):

   • Establish cloud best practices and governance
   • Regular architecture reviews and guidance
   • Develop certification and training program for engineering teams

3. Cloud Financial Management:

   • Implement FinOps practices and tooling
   • Regular cost reviews and optimization cycles
   • Showback/chargeback mechanisms to drive accountability

4. Abstraction Layers:

   • Create service abstractions to minimize direct cloud provider coupling
   • Develop infrastructure interfaces that could support multiple providers
   • Use cloud-agnostic tools and practices where practical

5. Hybrid Transition Strategy:

   • Phased migration from on-premises to cloud
   • Maintain hybrid capabilities during transition period
   • Clear exit criteria for legacy infrastructure decommissioning

Implementation Details

Phase 1: Foundation (Q4 2024)

1. Establish AWS Landing Zone and account structure
2. Implement core networking and security controls
3. Set up CI/CD pipelines for infrastructure
4. Deploy EKS clusters for development and staging
5. Migrate first non-critical workloads

Phase 2: Production Migration (Q1-Q2 2025)

1. Deploy production EKS clusters and platform services
2. Migrate core services to cloud infrastructure
3. Implement multi-region capabilities for critical services
4. Establish cloud cost management and optimization
5. Complete developer tooling and self-service capabilities

Phase 3: Advanced Capabilities (Q3-Q4 2025)

1. Implement advanced security and compliance controls
2. Deploy cross-region data synchronization
3. Optimize for global performance and availability
4. Enhance disaster recovery capabilities
5. Begin decommissioning legacy infrastructure

Considered Alternatives

1. Maintain and Expand On-Premises Infrastructure

Pros: Full control, potentially lower ongoing costs for stable workloads, no data sovereignty concerns
Cons: Limited agility, high capital expenditure, scaling limitations, operational overhead

This approach would not provide the agility and scalability needed for our strategic growth and would perpetuate our current limitations.

2. Single Cloud Provider (AWS Only)

Pros: Simplified operations, deeper integration between services, volume discounts, focused expertise
Cons: Vendor lock-in, limited negotiating leverage, regional provider limitations

While simpler operationally, this approach would increase our dependency on a single provider and limit flexibility.

3. Multi-Cloud with Equal Workload Distribution

Pros: Maximize negotiating leverage, no single provider dependency, best-of-breed services
Cons: Significantly increased complexity, higher operations costs, fragmented expertise, integration challenges

The operational complexity and cost of maintaining equal capabilities across multiple cloud providers outweighs the benefits for our current needs.

4. Cloud Service Provider (CSP) Abstraction Layer

Pros: Provider independence, standardized interfaces, easier migration between providers
Cons: Significant development overhead, lowest common denominator functionality, performance impacts

Building comprehensive abstractions across cloud providers would create substantial engineering overhead and limit access to valuable provider-specific capabilities.

References

1. AWS Well-Architected Framework (AWS Documentation)
2. “Cloud Strategy Leadership” (Gartner)
3. “Architecting for the Cloud: AWS Best Practices” (AWS Whitepaper)
4. “Multi-cloud: The good, the bad and the ugly” (ThoughtWorks Technology Radar)
5. Terraform Documentation (Terraform.io)
6. “Cloud Native Infrastructure” by Justin Garrison and Kris Nova

Decision Record History

Date	Version	Description	Author
2024-09-10	0.1	Initial draft	Marcus Johnson
2024-09-18	0.2	Added implementation phases and domain details	Patricia Lopez
2024-09-25	0.3	Incorporated feedback from architecture review	David Boyne
TBD	1.0	Pending approval	Architecture Board

Appendix A: Cloud Infrastructure Architecture

Appendix B: Deployment Architecture

Appendix C: AWS Account Structure