Let's see what happens when I try to upgrade a #NixOS 17.09 system to 24.11
lmao that did not work at all
The problem seems to be the Nix 2.0 release, as newer versions of nixpkgs require it, and 17.09 still has a Nix 1.x. Also for some reason mapAttrs is missing
Let's take a detour through 18.03 instead! Which ships Nix 2.x but also evaluates correctly with Nix 1.x, it seems
Another detour through 19.09 because of a Nix >= 2.2 requirement...
lmfao it ran out of memory while evaluating, because of course it did
What the hell, the upgrade to 19.09 succeeded but turned off my swapfile in the process??
Also I am basically playing a game of "how many soft-deprecated option warnings can I collect before Nix decides that it's had enough and I must fix these options *right now*"
Another detour through 21.11. Can I install 24.11 now?
Well, through 23.05 we go.
For some reason, I feel like this upgrade process could be improved. #NixOS
We have made it to 24.11, that's 7 years worth of #NixOS releases! Albeit with a detour through 4 intermediate releases.
It's about the journey, not the destination?
The system still boots fine, too!
I do have to say, I'm not impressed with Nix using an assert to check protocol compatibility for nix-copy-closure, leading to it just coredumping without a useful error message if you try to copy to a too-old #NixOS installation...
Alright, I should now have daily automated client-encrypted backups of all* my servers to two locations, one in the US and one in the Netherlands.
* except the 'workbot' server, which is a dedicated server that only handles high-resource workloads on ephemeral bulk data, like the seekseek crawler backend, and is not allowed to contain any critical data to begin with
@joepie91 swapfiles are not idempotent 
@joepie91 wait, the proper way to keep my Nix updated is not to leave those warnings be warnings until they've become hard errors?
Also, even a remote deployment via morph didn't work on this system, because the protocol underlying nix-copy-closure has changed enough that my local copy of Nix was incompatible with the one on the other system