ADR-001: Multi-Cluster Architecture Pattern¶

Status¶

Accepted

Date¶

2024-12-01

Context¶

The RH OVE ecosystem needs to support multiple environments (production, staging, development) while maintaining centralized governance, security, and operational oversight. The organization requires scalable infrastructure that can grow horizontally and support geographic distribution.

Decision¶

We will implement a multi-cluster architecture pattern with: - One Management Cluster: Centralized control plane for governance, GitOps, security, and monitoring - Multiple Application Clusters: Dedicated workload execution environments per environment type

Rationale¶

Advantages¶

Separation of Concerns: Clear boundaries between management and workload execution
Scalability: Horizontal scaling by adding application clusters as needed
Security: Network-level isolation between environments
Operational Efficiency: Centralized management reduces operational overhead
Fault Isolation: Issues in one cluster don't affect others
Resource Optimization: Right-size clusters based on workload requirements

Alternatives Considered¶

Single Large Cluster: Rejected due to blast radius and resource contention
Completely Separate Clusters: Rejected due to operational complexity and lack of centralized governance
Namespace-based Multi-tenancy: Rejected due to insufficient isolation for production workloads

Implementation Details¶

Management Cluster Components¶

Red Hat Advanced Cluster Management (RHACM)
ArgoCD Hub for GitOps
Red Hat Advanced Cluster Security (RHACS)
Federated Prometheus for monitoring
Centralized logging aggregation
Rubrik backup management

Application Cluster Types¶

Production: High-availability, performance-optimized
Staging: Production-like for testing
Development: Resource-optimized for development workflows

Network Architecture¶

Dedicated network segments per cluster type
VPN/Private connectivity between management and application clusters
Zero-trust network principles

Consequences¶

Positive¶

Improved security posture through cluster-level isolation
Simplified compliance and audit processes
Better resource utilization and cost optimization
Enhanced disaster recovery capabilities
Reduced blast radius for security incidents

Negative¶

Increased network complexity
Additional operational overhead for cluster lifecycle management
Potential data synchronization challenges
Learning curve for multi-cluster operations

Compliance Considerations¶

Meets enterprise security requirements for environment isolation
Supports regulatory compliance through audit trail separation
Enables data residency requirements through geographic cluster placement

Monitoring and Observability¶

Centralized metrics collection via Prometheus federation
Unified logging through log forwarding to management cluster
Cross-cluster distributed tracing capabilities
Centralized alerting and incident management