# Sovereign Cloud Federation Methodology

## Overview

This document defines the methodology for creating Sovereign Clouds using multiple global regions with fully federated data stores, enabling data sovereignty while maintaining global scale and performance.

## Core Principles

1. **Data Sovereignty**: Data remains within designated sovereign boundaries
2. **Federated Architecture**: Distributed data stores with federation protocols
3. **Global Consistency**: Eventual consistency across regions
4. **Regulatory Compliance**: Meet all local regulatory requirements
5. **Performance Optimization**: Low-latency access to local data
6. **Disaster Resilience**: Cross-region redundancy and failover

## Sovereign Cloud Architecture

### 1. Regional Sovereignty Zones

```typescript
interface SovereigntyZone {
  id: string
  name: string
  country: string
  region: string
  regulatoryFrameworks: string[] // GDPR, CCPA, etc.
  dataResidency: {
    required: boolean
    allowedRegions: string[]
    prohibitedRegions: string[]
  }
  complianceRequirements: ComplianceRequirement[]
  datacenters: Datacenter[]
  federatedStores: FederatedStore[]
}
```

### 2. Federated Data Store Architecture

#### Store Types

**Primary Store (Sovereign Region)**:
- Master copy of data for sovereign region
- All writes go to primary first
- Enforces data residency rules
- Local regulatory compliance

**Replica Stores (Other Regions)**:
- Read-only replicas for performance
- Synchronized via federation protocol
- Can be promoted to primary on failover
- Filtered based on data residency rules

**Metadata Store (Global)**:
- Global metadata and indexes
- No sensitive data
- Enables cross-region queries
- Federation coordination

### 3. Federation Protocol

#### Write Path

```
User Request (Region A)
    ↓
Primary Store (Region A) - Write
    ↓
Federation Coordinator
    ↓
Metadata Store (Global) - Update Index
    ↓
Replica Stores (Other Regions) - Async Replication
    ↓
Compliance Check (Data Residency)
    ↓
Selective Replication (Only to allowed regions)
```

#### Read Path

```
User Request (Region A)
    ↓
Check Metadata Store (Global) - Find Data Location
    ↓
Route to Primary Store (Region A) - Read
    ↓
If not in Region A:
    ↓
Check Replica Store (Region A) - Read
    ↓
If not available:
    ↓
Cross-Region Query (With Compliance Check)
```

## Data Residency and Sovereignty Rules

### Rule Engine

```typescript
interface DataResidencyRule {
  id: string
  dataType: string
  sourceRegion: string
  allowedRegions: string[]
  prohibitedRegions: string[]
  encryptionRequired: boolean
  retentionPolicy: RetentionPolicy
  accessControl: AccessControlPolicy
}
```

### Rule Evaluation

1. **Data Classification**: Classify data by sensitivity and type
2. **Regulatory Mapping**: Map to applicable regulations
3. **Residency Determination**: Determine required residency
4. **Replication Decision**: Allow/deny replication based on rules
5. **Encryption Enforcement**: Encrypt data in transit and at rest

## Federated Store Implementation

### 1. PostgreSQL Federation

**Citus Extension**:
- Distributed PostgreSQL with Citus
- Sharding across regions
- Cross-shard queries
- Automatic failover

**PostgreSQL Foreign Data Wrappers**:
- Connect to remote PostgreSQL instances
- Query across regions
- Transparent federation

**Implementation**:
```sql
-- Create foreign server
CREATE SERVER foreign_region_a
FOREIGN DATA WRAPPER postgres_fdw
OPTIONS (host 'region-a.phoenix.io', port '5432', dbname 'phoenix');

-- Create foreign table
CREATE FOREIGN TABLE users_region_a (
  id UUID,
  name VARCHAR(255),
  region VARCHAR(50)
) SERVER foreign_region_a;

-- Federated query
SELECT * FROM users_region_a
UNION ALL
SELECT * FROM users_region_b;
```

### 2. MongoDB Federation

**MongoDB Sharded Clusters**:
- Shard by region
- Zone-based sharding
- Cross-zone queries
- Automatic balancing

**MongoDB Change Streams**:
- Real-time replication
- Event-driven synchronization
- Conflict resolution

### 3. Redis Federation

**Redis Cluster**:
- Multi-region Redis clusters
- Cross-cluster replication
- Geographic distribution

**Redis Sentinel**:
- High availability
- Automatic failover
- Cross-region monitoring

### 4. Object Store Federation

**S3-Compatible Federation**:
- Regional object stores (MinIO/Ceph)
- Cross-region replication
- Versioning and lifecycle
- Access control

## Federation Coordinator Service

### Responsibilities

1. **Replication Orchestration**:
   - Coordinate data replication
   - Manage replication topology
   - Handle replication conflicts

2. **Compliance Enforcement**:
   - Enforce data residency rules
   - Validate regulatory compliance
   - Audit data movements

3. **Query Routing**:
   - Route queries to appropriate stores
   - Aggregate results from multiple regions
   - Optimize query performance

4. **Conflict Resolution**:
   - Detect conflicts
   - Resolve using strategies (last-write-wins, CRDTs)
   - Maintain consistency

### Implementation

**File**: `api/src/services/federation-coordinator.ts`

```typescript
class FederationCoordinator {
  async replicateData(
    sourceRegion: string,
    targetRegion: string,
    data: any,
    rules: DataResidencyRule[]
  ): Promise<ReplicationResult>

  async routeQuery(
    query: Query,
    userRegion: string
  ): Promise<QueryResult>

  async resolveConflict(
    conflict: Conflict
  ): Promise<Resolution>

  async enforceCompliance(
    data: any,
    operation: 'READ' | 'WRITE' | 'REPLICATE'
  ): Promise<ComplianceResult>
}
```

## Multi-Region Data Synchronization

### Synchronization Strategies

**1. Eventual Consistency**:
- Async replication
- Accept temporary inconsistencies
- Conflict resolution on read

**2. Strong Consistency (Selected Data)**:
- Synchronous replication for critical data
- Higher latency
- Guaranteed consistency

**3. CRDTs (Conflict-Free Replicated Data Types)**:
- Automatic conflict resolution
- No coordination required
- Eventual consistency guaranteed

### Synchronization Protocol

```
Write Operation
    ↓
Primary Store (Write + Log)
    ↓
Event Stream (Kafka/NATS)
    ↓
Federation Coordinator
    ↓
Compliance Check
    ↓
Replication Queue (Per Region)
    ↓
Replica Stores (Apply Changes)
    ↓
Acknowledgment
```

## Compliance and Governance

### Regulatory Compliance

**GDPR (EU)**:
- Data must remain in EU
- Right to erasure
- Data portability
- Privacy by design

**CCPA (California)**:
- California data residency
- Consumer rights
- Data deletion

**HIPAA (Healthcare)**:
- Healthcare data protection
- Audit trails
- Access controls

**SOX (Financial)**:
- Financial data integrity
- Audit requirements
- Retention policies

### Compliance Enforcement

```typescript
class ComplianceEnforcer {
  async checkDataResidency(
    data: any,
    targetRegion: string
  ): Promise<boolean>

  async validateRegulatoryCompliance(
    data: any,
    operation: string,
    region: string
  ): Promise<ComplianceResult>

  async enforceRetentionPolicy(
    data: any,
    region: string
  ): Promise<void>

  async auditDataAccess(
    data: any,
    user: User,
    operation: string
  ): Promise<AuditLog>
}
```

## Disaster Recovery and Failover

### Failover Strategy

**1. Regional Failover**:
- Promote replica to primary
- Update routing
- Resume operations

**2. Cross-Region Failover**:
- Failover to backup region
- Data synchronization
- Service restoration

**3. Gradual Recovery**:
- Incremental data sync
- Service restoration
- Validation

### Recovery Procedures

```typescript
class DisasterRecoveryService {
  async initiateFailover(
    failedRegion: string,
    targetRegion: string
  ): Promise<FailoverResult>

  async promoteReplica(
    replicaRegion: string
  ): Promise<void>

  async synchronizeData(
    sourceRegion: string,
    targetRegion: string
  ): Promise<SyncResult>

  async validateRecovery(
    region: string
  ): Promise<ValidationResult>
}
```

## Performance Optimization

### 1. Local-First Architecture

- Read from local replica when possible
- Write to local primary
- Minimize cross-region queries

### 2. Caching Strategy

- Regional caches (Redis)
- Cache invalidation across regions
- Cache warming for critical data

### 3. Query Optimization

- Route queries to nearest store
- Parallel queries to multiple regions
- Result aggregation and deduplication

### 4. Data Partitioning

- Partition by region
- Co-locate related data
- Minimize cross-partition queries

## Implementation Roadmap

### Phase 1: Foundation (90 days)
1. Define sovereignty zones
2. Implement basic federation protocol
3. Deploy primary stores in each region
4. Basic replication

### Phase 2: Advanced Federation (120 days)
1. Implement federation coordinator
2. Advanced replication strategies
3. Compliance enforcement
4. Query routing optimization

### Phase 3: Disaster Recovery (90 days)
1. Failover automation
2. Cross-region synchronization
3. Recovery procedures
4. Testing and validation

### Phase 4: Optimization (60 days)
1. Performance tuning
2. Caching optimization
3. Query optimization
4. Monitoring and alerting

## Database Schema

### Federation Metadata

```sql
CREATE TABLE sovereignty_zones (
  id UUID PRIMARY KEY,
  name VARCHAR(255) NOT NULL,
  country VARCHAR(100) NOT NULL,
  region VARCHAR(100) NOT NULL,
  regulatory_frameworks TEXT[],
  data_residency_rules JSONB,
  created_at TIMESTAMP,
  updated_at TIMESTAMP
);

CREATE TABLE federated_stores (
  id UUID PRIMARY KEY,
  zone_id UUID REFERENCES sovereignty_zones(id),
  store_type VARCHAR(50), -- POSTGRES, MONGODB, REDIS, OBJECT_STORE
  connection_string TEXT,
  role VARCHAR(50), -- PRIMARY, REPLICA, METADATA
  replication_config JSONB,
  created_at TIMESTAMP,
  updated_at TIMESTAMP
);

CREATE TABLE data_residency_rules (
  id UUID PRIMARY KEY,
  data_type VARCHAR(100),
  source_zone_id UUID REFERENCES sovereignty_zones(id),
  allowed_zones UUID[],
  prohibited_zones UUID[],
  encryption_required BOOLEAN,
  retention_policy JSONB,
  created_at TIMESTAMP,
  updated_at TIMESTAMP
);

CREATE TABLE replication_logs (
  id UUID PRIMARY KEY,
  source_store_id UUID REFERENCES federated_stores(id),
  target_store_id UUID REFERENCES federated_stores(id),
  data_id UUID,
  operation VARCHAR(50), -- INSERT, UPDATE, DELETE
  status VARCHAR(50), -- PENDING, COMPLETED, FAILED
  compliance_check JSONB,
  created_at TIMESTAMP,
  completed_at TIMESTAMP
);
```

## Monitoring and Observability

### Key Metrics

1. **Replication Metrics**:
   - Replication lag
   - Replication throughput
   - Replication failures

2. **Compliance Metrics**:
   - Compliance violations
   - Data residency violations
   - Audit log completeness

3. **Performance Metrics**:
   - Query latency
   - Cross-region query performance
   - Cache hit rates

4. **Availability Metrics**:
   - Store availability
   - Failover times
   - Recovery times

