You know the kind of server.
It has been running for three years. The original setup came from a script, a few changes were made by hand during incidents, and the documentation stopped matching reality somewhere along the way. Everyone is slightly nervous about touching it. Rebuilding it from scratch would be an archaeological project.
The problem is not that the team forgot to automate everything. It is that the machine is partly defined by its history: every command, hotfix, and one-off decision that happened to it.
NixOS takes a different approach. Instead of describing the steps used to configure a machine, you describe the state you want. Services, users, packages, firewall rules, and many other system properties live in a declarative configuration.
NixOS is not just another way to automate shell commands. It turns the desired state of the operating system into something you can build, review, and version.
