Add new file

app.yaml

+runtime: python
+env: flex
+entrypoint: gunicorn -b :$PORT main:app
+
+runtime_config:
+  python_version: 3
+
+# This sample incurs costs to run on the App Engine flexible environment. 
+# The settings below are to reduce costs during testing and are not appropriate
+# for production use. For more information, see:
+# https://cloud.google.com/appengine/docs/flexible/python/configuring-your-app-with-app-yaml
+manual_scaling:
+  instances: 1
+resources:
+  cpu: 1
+  memory_gb: 0.5
+  disk_size_gb: 10