Why does nix cache signatures in ~root/.cache/nix?

[ninegua]

I was trying to fix a problem after getting the following warning when using a self-hosted nix-serve cache server:

nix-store --realise /nix/store/nklk455j6mm1dzlisdr0mjmp8bv3zlsg-bar-file --option extra-binary-caches https://foo.cache.server
...
warning: substituter 'https://foo.cache.server' does not have a valid signature for path '/nix/store/nklk455j6mm1dzlisdr0mjmp8bv3zlsg-bar-file'

The problem was server side had a nginx https proxy port misconfiguration that pointed the service to something else other than the nix-serve port. I then fixed this mistake, but I still got the above warning when running the above command.

I tried removing ~/.cache/nix/ according to (edolstra/nix-serve#10 (comment)), but it didn't work.

I then tried removing ~root/.cache/nix/, and it worked.

I'm using NixOS and nix 2.2.2, and I've always been using nix commands from my own user account. So why is nix looking for cache information (e.g. signatures) under the root user's directory?

[stale]

I marked this as stale due to inactivity. → More info

[stale]

I closed this issue due to inactivity. → More info

[LucianU]

@ninegua, even though the issue was closed, I think the answer is: because nix daemon runs as root. So that means it saves stuff under the root account.