The Python runtime

Python was the first supported language on App Engine, and remains a popular choice for many GCP users. Python applications in the App Engine standard environment take the form of a set of routes and their associated route handlers, as defined in any app.yaml configuration file. Each handler is composed of a URL and an associated action to take, along with several optional attributes.

The URL is a regular expression used to match handlers to incoming requests and supports regular expression backreferences, the value of which is available in the script specification. For the associated action to take on a given URL, the handler specifies a script to execute or a static file/directory to serve at that URL. Optional attributes modify the behavior of a given handler. For example, access to a given handler can be restricted to project members by including the optional login: admin attribute.