Add "buildfarmer" user to hydra and server7

hosts/hydra/configuration.nix

@@ -5,8 +5,9 @@
     <nixpkgs/nixos/modules/profiles/minimal.nix>
     ./hydra.nix
     ./cache.nix
-    ./../../lib/hq.nix
-    ./../../lib/emery.nix
+    ../../lib/hq.nix
+    ../../lib/emery.nix
+    ../../lib/buildfarmer.nix
   ];
 
   networking.interfaces.eth0.preferTempAddress = false;
@@ -19,6 +20,7 @@
   programs.mosh.enable = true;
 
   nix = {
+    distributedBuilds = true;
     package = pkgs.nixFlakes;
     useSandbox = false;
     maxJobs = lib.mkDefault 4;

hosts/hydra/hydra.nix

@@ -14,7 +14,8 @@
       {
         hostName = "server7.hq.c3d2.de";
         system = "x86_64-linux";
-        maxJobs = 2;
+        sshUser = "buildfarmer";
+        sshKey = "/root/.ssh/id_ed25519";
       }
     ];
   };

hosts/server7/configuration.nix

@@ -7,6 +7,7 @@ in {
     ../../lib/hq.nix
     ../../lib/default-gateway.nix
     ../../lib/emery.nix
+    ../../lib/buildfarmer.nix
     ../../lib/yggdrasil.nix
     ./containers
     ./hardware-configuration.nix
@@ -42,11 +43,12 @@ in {
     package = pkgs.nixFlakes;
     extraOptions = "experimental-features = nix-command flakes";
     gc.automatic = true;
-    trustedUsers = [ "root" ];
+    distributedBuilds = true;
     buildMachines = [{
       hostName = "hydra.hq.c3d2.de";
       system = "x86_64-linux";
-      maxJobs = 2;
+      sshUser = "buildfarmer";
+      sshKey = "/root/.ssh/id_ed25519";
     }];
   };
 

lib/buildfarmer.nix

@@ -0,0 +1,15 @@
+{ config, pkgs, ... }:
+
+{
+  users.users.buildfarmer = {
+    isNormalUser = false;
+    description = "User for remote Nix builds";
+    useDefaultShell = true;
+    openssh.authorizedKeys.keys = [
+      "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIMwS9B/d6QJUyZW9b52R2TlJgkI5oGDyOvzMN7H9Cz4/ hydra@hydra"
+      "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAINA3x2+5ieo5QgehFHqXCYAYZSP8dxXyE1E/fSLnny8y root@serve7"
+    ];
+  };
+
+  nix.trustedUsers = [ "buildfarmer" ];
+}