How to Migrate from App Engine Python 2 to Python 3 with Minimal Risk

This article discusses a software migration journey from Python 2 to Python 3 for GQueues, a web application running on Google App Engine.

The article explains how the built-in services on App Engine were removed in the second-generation runtimes, and how GQueues first migrated to Google Cloud replacements for these services.

The conventional approach for migrating to Python 3 is discussed but deemed too risky for GQueues. Instead, a strategy of migrating a single feature at a time to a Python 3 server alongside the Python 2 app was adopted, using a load balancer to direct traffic.

The benefits of this approach are outlined, including reduced risk, limited downtime, and easy monitoring of progress.