Reapply "Merge pull request #565 from NixOS/flake-refactoring"

This reverts commit e54642e.

Author: Mic92

.github/workflows/ci.yml

@@ -32,6 +32,9 @@ jobs:
           - caliban.nixos.org
           - elated-minsky
           - sleepy-brown
+          - haumea
+          - pluto
+          - mimas
     steps:
       - uses: actions/checkout@v4
       - uses: cachix/install-nix-action@v30

build/.envrc

@@ -1,2 +1,2 @@
 # shellcheck shell=bash
-use flake
+use flake .#build

build/flake-module.nix

@@ -0,0 +1,76 @@
+{
+  inputs,
+  lib,
+  ...
+}:
+let
+  flakesModule = {
+    imports = [
+      inputs.agenix.nixosModules.age
+      inputs.disko.nixosModules.disko
+      inputs.hydra.nixosModules.hydra
+    ];
+
+    nixpkgs.overlays = [
+      inputs.nix.overlays.default
+      inputs.hydra.overlays.default
+      inputs.nixos-channel-scripts.overlays.default
+      inputs.rfc39.overlays.default
+    ];
+  };
+in
+{
+  flake = {
+    nixosConfigurations.haumea = lib.nixosSystem {
+      system = "x86_64-linux";
+
+      modules = [
+        flakesModule
+        ./haumea
+      ];
+    };
+
+    nixosConfigurations.pluto = lib.nixosSystem {
+      system = "x86_64-linux";
+
+      modules = [
+        flakesModule
+        ./pluto
+      ];
+    };
+
+    nixosConfigurations.mimas = lib.nixosSystem {
+      system = "x86_64-linux";
+
+      modules = [
+        flakesModule
+        ./mimas
+      ];
+    };
+    colmena =
+      {
+        meta = {
+          description = "NixOS.org infrastructure";
+          nixpkgs = inputs.nixpkgs.legacyPackages.x86_64-linux;
+        };
+      }
+      // builtins.mapAttrs (name: value: {
+        nixpkgs.system = value.config.nixpkgs.system;
+        imports = value._module.args.modules;
+        deployment = {
+          targetHost = "${name}.nixos.org";
+        };
+      }) self.nixosConfigurations;
+  };
+
+  perSystem =
+    { pkgs, inputs', ... }:
+    {
+      devShells.build = pkgs.mkShell {
+        buildInputs = [
+          inputs'.agenix.packages.agenix
+          inputs'.colmena.packages.colmena
+        ];
+      };
+    };
+}