Adding custom domains to AWS Lambda MicroVMs with Application Load Balancer

This article explains how to expose AWS Lambda MicroVMs under custom domains using Application Load Balancer (ALB) with host header rewrite and AWS PrivateLink.

• ALB terminates TLS with ACM certificate and rewrites Host header to real MicroVM endpoint
• Regex-based listener rule captures MicroVM ID from custom domain and maps to service endpoint
• PrivateLink provides private connectivity from ALB to AWS managed MicroVM service
• CORS preflight and response headers handled at ALB with no application changes
• Wildcard Route 53 records map all custom subdomains to single ALB
• Deploy pattern using AWS CDK with configuration for hosted zone and custom domain base

This approach provides transparent custom domain access to MicroVMs using only networking primitives, eliminating CloudFront and compute overhead.