New engineers spend weeks reconstructing how a platform fits together, and reviewers approve changes without knowing why it is built as it is. This template records the structure in one place: the accounts, the network, the environments, identity, cost controls and backups. Every part has an owner, and the key decisions sit beside the reasons for them.

The sample describes the booking platform at Greystone Software, with three accounts, private networking, a preview environment API, workload identities and a quarterly restore test. Every name, figure and service is fictional. Replace the services, costs and decisions with your own, and set the date the document was last reviewed.