> I see people talking about using Kubernetes for internal applications.

I think the important issue when first starting a project is to create a "12 Factor App" so that if and when you create a Docker image and/or run the application in Kubernetes, you don't have to rewrite the entire application. Most of the tools I write run on the CLI but I am in fact a fan of Kubernetes for services, message processing and certain batch jobs simply because I don't have to manage their life-cycles.