Comment by exdsq

One really cool thing about NixOS is you declare the OS just like you might a DockerFile, and you can choose which configuration file you use at booting time. This lets you install applications just during up-time (to try out a new tool), add it to the configuration file if you like it, and roll back to the version before if it breaks something. Versions are declarative too (PSql == X.X.X) and upgrades/downgrades are set there too. If I want to share an environment with someone I can just share the configuration file minus the secrets.