Scale multi-tenant SaaS with per-tenant version pinning using Amazon CloudFront

This article demonstrates how to scale multi-tenant SaaS applications using CloudFront multi-tenant distributions with per-tenant version pinning, enabling zero-downtime version switching without Application Load Balancer scaling constraints.

• Use CloudFront multi-tenant distributions with a version parameter to route each tenant to their pinned version (ga, preview, canary)
• Store tenant configuration in DynamoDB with domain as partition key; DynamoDB Streams trigger Lambda to reconcile CloudFront distribution tenants
• Deploy per-version ASP.NET Core services on Amazon ECS behind a fixed set of Application Load Balancer path-based rules
• Onboard tenants with a single DynamoDB write; switch versions with a single update—no infrastructure changes required
• Resolve tenant identity from the Host header in ASP.NET Core middleware; lookup tenant configuration in DynamoDB with caching
• Supports multi-region extension using DynamoDB global tables and regional origins in CloudFront

This approach eliminates per-tenant load balancer rules and certificates, scales to 10,000 tenants per distribution, and enables instant zero-downtime version switches.