A YAML or JSON configuration file that declaratively defines the complete structure of a DigitalOcean App Platform application, including all services, workers, jobs, databases, domains, environment variables, and build configuration. App Specs enable infrastructure-as-code workflows and can be version-controlled in Git.
A team stores their App Spec in `.do/app.yaml` in their repository. When they onboard a new microservice, they add a new service block to the YAML and commit — App Platform automatically creates the new service, connects it to the shared database, and wires the environment variables without any manual console interaction.