Python 3.9 is now generally available.

google.appengine.api.appinfo.LoadSingleAppInfo

Loads a single AppInfo object where one and only one is expected.

This method validates that the values in the AppInfo match the validators that are defined in this file, in particular, AppInfoExternal.ATTRIBUTES.

app_info A file-like object or string. If the argument is a string, the argument is parsed as a configuration file. If the argument is a file-like object, the data is read, then parsed.

An instance of AppInfoExternal as loaded from a YAML file.

ValueError If a specified service is not valid.
EmptyConfigurationFile If there are no documents in YAML file.
MultipleConfigurationFile If more than one document exists in the YAML file.
DuplicateBackend If a backend is found more than once in the backends directive.
yaml_errors.EventError If the app.yaml file fails validation.
appinfo_errors.MultipleProjectNames If the app.yaml file has both an application directive and a project directive.