fix: remote building to also use localhost

machines/moritz-desktop/configuration.nix

@@ -23,10 +23,7 @@
   # This only works however if you have avahi running on your admin machine else use IP
   clan.core.networking.targetHost = "root@moritz-desktop";
 
-  our.buildMachines = {
-    enable = true;
-    speedFactor = 2;
-  };
+  our.buildMachines.enable = true;
 
   my = {
     ai.enable = true;

modules/remote_builders.nix

@@ -21,33 +21,38 @@
 
   others = filterAttrs (n: _v: n != config.networking.hostName) self.nixosConfigurations;
 
-  max = a: b:
-    if a > b
-    then a
-    else b;
-
   mkBuilder = hostName: attrs: let
     config' = attrs.config;
     cfg' = config'.our.buildMachines;
     pkgs' = attrs.pkgs;
   in
     mkIf cfg'.enable {
-      hostName = hostName;
-      sshUser = "remotebuild";
+      # NOTE: https://github.com/NixOS/nix/issues/3177
+      hostName =
+        if hostName == config.networking.hostName
+        then "local?root=/nix/store"
+        else hostName;
+      sshUser =
+        if hostName == config.networking.hostName
+        then null
+        else "remotebuild";
       # CPU architecture of the builder, and the operating system it runs.
       # If your builder supports multiple architectures
       # (e.g. search for "binfmt" for emulation),
       systems = [pkgs'.system] ++ config'.boot.binfmt.emulatedSystems;
       # Nix custom ssh-variant that avoids lots of "trusted-users" settings pain
-      protocol = "ssh-ng";
+      protocol =
+        if hostName == config.networking.hostName
+        then null
+        else "ssh-ng";
       # default is 1 but may keep the builder idle in between builds
       maxJobs = 3;
-      speedFactor = max (cfg'.speedFactor - cfg.speedFactor + 1) 1;
+      speedFactor = 1;
       supportedFeatures = cfg'.supportedFeatures;
       mandatoryFeatures = [];
     };
 
-  buildMachines = mapAttrsToList mkBuilder others;
+  buildMachines = mapAttrsToList mkBuilder self.nixosConfigurations;
 
   remotebuildKeys =
     mapAttrsToList (
@@ -81,11 +86,6 @@ in {
         benchmark    | Machine can generate metrics (means the builds usually takes the same amount of time)
       '';
     };
-    speedFactor = mkOption {
-      type = types.int;
-      default = 1;
-      description = "How fast is the builder compared to your local machine";
-    };
   };
   config = mkIf cfg.enable {
     users.users.remotebuild = {