Refactor the Nix config management.

nix-system-configs/modules/toolsets/remote_building.nix

@@ -0,0 +1,50 @@
+{
+  config,
+  pkgs,
+  lib,
+  ...
+}: {
+  # THE FOLLOWING CODE BLOCK IS FOR COPYING TO OTHER CONFIGURATIONS, NOT FOR THIS FILE
+
+  nix.distributedBuilds = true;
+  nix.buildMachines = [
+    {
+      hostName = "nixos-build-machine";
+      system = "x86_64-linux";
+      sshUser = "nixremote";
+      sshKey = "/root/.ssh/nixremote";
+      maxJobs = 4;
+      speedFactor = 2;
+      supportedFeatures = ["nixos-test" "benchmark" "big-parallel" "kvm"];
+    }
+  ];
+
+  # Generate SSH key for remote building
+  systemd.services.generate-nixremote-key = {
+    description = "Generate SSH key for remote Nix builds";
+    wantedBy = ["multi-user.target"];
+    serviceConfig = {
+      Type = "oneshot";
+      RemainAfterExit = true;
+    };
+    script = ''
+      if [ ! -f /root/.ssh/nixremote ]; then
+        ${pkgs.openssh}/bin/ssh-keygen -t ed25519 -f /root/.ssh/nixremote -N "" -C "nix-remote-builder"
+      fi
+    '';
+  };
+
+  programs.ssh.extraConfig = ''
+    Host nixos-build-machine
+      HostName 10.1.1.3
+      IdentitiesOnly yes
+      IdentityFile /root/.ssh/nixremote
+      User nixremoteStrictHostKeyChecking accept-new
+  '';
+
+  # Manual step required: After rebuilding the client, copy /root/.ssh/nixremote.pub
+  # from the client to the build machine's users.users.nixremote.openssh.authorizedKeys.keys list,
+  # then rebuild the build machine.
+  # i.e on the client: run "cat /root.ssh/nixremote.pub"
+  # and copy the output to the build machine's configuration.nix
+}