Google App Engine introduction specify this Your application can run in one of three runtime environments: the Go environment, the Java environment, and the Python environment, which gives you a choice of Python 2.5 or the experimental Python 2.7.
However, when it comes to downloading a SDK, only one python package is available, and I can’t seem to find any option to select the version of Python my project will run on. Has anyone been faced with that?
All the information you need for how to use the Python 2.7 runtime is found in the GAE documentation under Using Python 2.7.
The short version: you need to set the ‘runtime’ configuration element in your app.yaml file to ‘python27’.