Three years of ephemeral NixOS: my experience resetting root on every boot

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Fresh OS installs are bliss. But the joy fades quickly as installing and uninstalling programs leave behind a trail of digital debris. Even configuration management and declarative systems like NixOS miss crucial bits, like the contents of /var/lib or stray dotfiles. This debris isn’t just unsightly. It can be load-bearing, crucial to the functioning of your system, but outside of your control, and not preserved on rebuilds. Full system backups merely preserve this chaos. I wanted a clean slate, automatically, every boot.

“Erase your darlings” inspired an idea in the NixOS community: allowlisting files and directories that persist across reboots. Anything not on the list gets wiped. The simplest implementation involves mounting / as a tmpfs (i.e. in RAM), and then bind-mounting or symlinking the allowlisted items to a disk-backed filesystem.
↫ Tuxes.uk

I dabbled in NixOS over the past week or so, and while I find it intriguing and can definitely see a use for it, I also found it rather needlessly cumbersome and over-engineered for something as simple as a desktop system. I felt like I was taking a whole bunch of additional steps to do basic things, without needing any of the benefits Nix and NixOS bring. This doesn’t mean Nix and NixOS are bad – just that for me, personally, it doesn’t fill any need I have.

Taking the Nix concept as far as starting with a completely fresh installation on every boot sounds absolutely insane to me. Of course, it’s not entirely fresh on every reboot, as several applications and important configuration elements do survive the reboot, but it’s still quite drastic compared to what everyone else is doing. Unsurprisingly, there are a few issues; it’s hard to know what really needs and doesn’t need saving, there might be some unexpected issues because software doesn’t expect to be wiped, and so on.

Overall though, it seems to work susprisingly well, and for a specific type of person, this is definitely bliss.