The DevOps movement gave us many ways to put Python applications into production. But should your application care? Should it need to know whether it’s running on your notebook, on a server, in a Docker container, or in some cloud platform as a service? It should not, because environment-agnostic applications are easier to test, easier to deploy, easier to handle, and easier to scale. But how can you practically structure and configure your applications to make them indifferent to the environment they run in? How do secrets fit into the picture? And where do you put that log file? By the end of this talk you’ll know the tools and techniques that enable you to write such Python applications and you’ll be ready for the next big change.