Currently there are a bunch of really wacky hacks required to get
nixpkgs path correctly set up under flake configs such that `nix run
nixpkgs#hello` and `nix run -f '<nixpkgs>' hello` hit the nixpkgs that
the system was built with. In particular you have to use specialArgs or
an anonymous module, and everyone has to include this hack in their own
configs.
We can do this for users automatically.
NixOS/nixpkgs@e456032add
Co-authored-by: Antoine Cotten <hello@acotten.com>
Before this commit, aarch64 users building the following configuration
would end up with an aarch64-linux builder, while after it, they get the
x86_64-linux builder they expect:
```nix
nix.linux-builder = {
enable = true;
package = pkgs.darwin.linux-builder-x86_64;
};
```
Before, in order to get an x86_64-linux builder, they would have needed
to use this configuration instead:
```nix
nix.linux-builder = {
enable = true;
config.nixpkgs.hostPlatform = "x86_64-linux";
systems = ["x86_64-linux"];
};
```
The reason for this is that the linux-builder module calls `override` on
the package option, and the `linux-builder-x86_64` package is also
defined using override:
```nix
linux-builder-x86_64 = linux-builder.override {
modules = [ { nixpkgs.hostPlatform = "x86_64-linux"; } ];
};
```
The module was effectively discarding the `nixpkgs.hostPlatform` option.
Example issue: https://github.com/NixOS/nixpkgs/issues/313784
This commit updates the nix.conf validation logic to accommodate
different versions of Nix. It introduces a conditional assignment
of the `showCommand` variable, which determines the appropriate
command to use based on the Nix version. For versions at least
"2.20pre", it uses "config show"; otherwise, it falls back to
"show-config". This change ensures compatibility across various
Nix releases.
This commit adds a protocol option for the `linux-builder` and defaults
it to `ssh-ng`. I have observed it needing this with the following:
``` sh
$ nix store ping --store ssh://linux-builder
Store URL: ssh://linux-builder
$ nix store ping --store ssh-ng://linux-builder
Store URL: ssh-ng://linux-builder
Version: 2.18.1
Trusted: 0
```
This seems to make the difference on whether or not Nix picks up
`linux-builder` as an available builder.
This is based on the current NixOS `nixpkgs` module, adjusted for the
nix-darwin context and without adding the options due for deprecation
in NixOS.
This gives us the ability to set the package set modularly through
`nixpkgs.pkgs` and builds up infrastructure for handling user-specified
Nixpkgs instantiations more robustly.
The cross-compilation options are currently not very useful due to
even Darwin->Darwin cross-compilation not being wholly functional
yet, but it looks feasible to build an `aarch64-darwin` system from
`x86_64-darwin` with some patching and it should be possible to make
cross-compilation more widely supported after the Darwin SDK situation
in Nixpkgs improves.
One casualty is the error for setting `nixpkgs.*` options when
overriding the package set. That could be ported over to this new
scheme, but it'd increase divergence with the NixOS module and reduce
cross-compatibility of configurations, so I lean towards adding it
upstream to NixOS if anything. (But if people want to keep it I can add
it back.)
