Tech firm resurrects 2011 vpc zombie with ipv6 and ha bolts: zero downtime via cdk sorcery and endless manual tweaks

THRON, a company that fully transitioned to Amazon Web Services (AWS) by 2025, recently undertook a major overhaul of its Virtual Private Cloud (VPC) infrastructure to address issues with high availability, scalability, and security. The company's original VPC, created in 2011, had become outdated and was struggling to support its growing adoption of serverless technologies. To evolve the existing VPC without causing downtime, THRON's team used an infrastructure-as-code (IaC) approach with AWS CDK, adding new features such as high availability, IPv6 support, and expanded CIDR blocks. The team imported the current VPC into CDK, updated network resources, and migrated over 260 resources from old subnets to new ones, including EC2 instances, Lambda functions, and Fargate tasks. The successful migration, which took place in 2025, has future-proofed THRON's infrastructure, allowing it to support its continued growth and adoption of new technologies. The project's success demonstrates the importance of careful planning, testing, and execution in complex infrastructure migrations.