App Engine Routing. For more information about services, versions,
and instances see An Overview of App Engine
<https://cloud.google.com/appengine/docs/python/an-overview-of-app-
engine>, Microservices Architecture on Google App Engine
<https://cloud.google.com/appengine/docs/python/microservices-on-app-
engine>, App Engine Standard request routing
<https://cloud.google.com/appengine/docs/standard/python/how-requests-
are-routed>, and App Engine Flex request routing
<https://cloud.google.com/appengine/docs/flexible/python/how-requests-
are-routed>.
.. attribute:: service
App service. By default, the job is sent to the service which is the default service when the job is attempted.
App instance. By default, the job is sent to an instance
which is available when the job is attempted. Requests can
only be sent to a specific instance if manual scaling is used
in App Engine Standard
<https://cloud.google.com/appengine/docs/python/an-overview-
of-app-engine?hl=en_US#scaling_types_and_instance_classes>.
App Engine Flex does not support instances. For more
information, see App Engine Standard request routing
<https://cloud.google.com/appengine/docs/standard/python/how-
requests-are-routed> and App Engine Flex request routing
<https://cloud.google.com/appengine/docs/flexible/python/how-
requests-are-routed>__.