Impossible to override nix.conf configuration

[simonzkl]

With Determinate Nix it's impossible to override certain configuration options that Determinate Nix auto-generates to /etc/nix/nix.conf. This is a feature regression from Nix where any configuration option can be overridden.

There two issues:

• Some sections in /etc/nix/nix.conf take precedence over /etc/nix/nix.custom.conf
• All the extra- options cannot be overridden at all because they are always merged.

For example it's impossible to remove FlakeHub from extra-trusted-substituters or change nix-path, always-allow-substitutes and many other options. Changing /etc/nix/nix.conf itself is not an option as the config file regularly gets overwritten.

[Isolaryn]

I would also like to know of a solution to this going forward.