Multi-Cloud Strategy: Architecture and Implementation

// Abstract cloud provider differences
interface CloudProvider {
  upload(bucket: string, key: string, data: Buffer): Promise<void>;
  download(bucket: string, key: string): Promise<Buffer>;
  delete(bucket: string, key: string): Promise<void>;
}

class S3Provider implements CloudProvider {
  async upload(bucket: string, key: string, data: Buffer) {
    const s3 = new AWS.S3();
    await s3.putObject({ Bucket: bucket, Key: key, Body: data }).promise();
  }
}

class AzureBlobProvider implements CloudProvider {
  async upload(bucket: string, key: string, data: Buffer) {
    const blobService = AzureStorage.createBlobService();
    await blobService.createBlockBlobFromText(bucket, key, data);
  }
}

// Use factory pattern
class CloudProviderFactory {
  static create(provider: 'aws' | 'azure' | 'gcp'): CloudProvider {
    switch (provider) {
      case 'aws': return new S3Provider();
      case 'azure': return new AzureBlobProvider();
      case 'gcp': return new GCPStorageProvider();
    }
  }
}

class MultiCloudOrchestrator {
  private providers: Map<string, CloudProvider> = new Map();
  
  constructor() {
    this.providers.set('aws', CloudProviderFactory.create('aws'));
    this.providers.set('azure', CloudProviderFactory.create('azure'));
    this.providers.set('gcp', CloudProviderFactory.create('gcp'));
  }
  
  async uploadWithFallback(
    bucket: string, 
    key: string, 
    data: Buffer
  ): Promise<void> {
    const errors: Error[] = [];
    
    for (const [name, provider] of this.providers) {
      try {
        await provider.upload(bucket, key, data);
        console.log(`Uploaded to ${name} successfully`);
        return;
      } catch (error) {
        errors.push(error);
        console.error(`Failed to upload to ${name}:`, error);
      }
    }
    
    throw new Error(`All providers failed: ${errors.map(e => e.message).join(', ')}`);
  }
}

class MultiCloudReplicator {
  async replicate(
    sourceProvider: string,
    targetProviders: string[],
    bucket: string,
    key: string
  ): Promise<void> {
    // Download from source
    const source = this.providers.get(sourceProvider)!;
    const data = await source.download(bucket, key);
    
    // Upload to targets in parallel
    await Promise.all(
      targetProviders.map(async (targetName) => {
        const target = this.providers.get(targetName)!;
        await target.upload(bucket, key, data);
        console.log(`Replicated to ${targetName}`);
      })
    );
  }
}

class CostOptimizer {
  // Track costs across providers
  async calculateCosts(storage: StorageSpec, compute: ComputeSpec): Promise<CostComparison> {
    const costs = await Promise.all([
      this.calculateAWSCosts(storage, compute),
      this.calculateAzureCosts(storage, compute),
      this.calculateGCPCosts(storage, compute)
    ]);
    
    return {
      aws: costs[0],
      azure: costs[1],
      gcp: costs[2],
      cheapest: costs.sort((a, b) => a.total - b.total)[0]
    };
  }
}