This case study details AGL Energy's migration from on-premises infrastructure to the cloud using HashiCorp Terraform. AGL Energy, a leading energy provider in Australia, faced significant challenges due to the aging of its third-party datacenters and the need to reduce business risk. The company formed over 50 teams to execute a multi-year migration plan, moving more than 210 applications to Microsoft Azure. The implementation of Terraform Enterprise allowed AGL to automate infrastructure provisioning, significantly reducing the time to deploy new virtual machines from a week to less than 10 minutes. The case study outlines how Terraform's infrastructure as code capabilities facilitated faster, secure, and consistent builds, thus enhancing team productivity and enabling AGL to complete its datacenter exit program efficiently. The document also discusses the future phases of AGL's cloud journey, focusing on optimizing cloud resources and improving access control features.