From 41d962082025f3deeeb8652955b57e12bc01db58 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?L=C3=A9ana=20=E6=B1=9F?= <leana.jiang+git@icloud.com>
Date: Thu, 1 Jan 2026 21:31:42 +0100
Subject: [PATCH] hetzner_benchmark: set up as nix builder

---
 nix/configurations/hetzner_benchmark.nix      |  1 +
 .../hetzner_benchmark/nixos/builder.nix       | 31 +++++++++++++++++++
 2 files changed, 32 insertions(+)
 create mode 100644 nix/configurations/hetzner_benchmark/nixos/builder.nix

diff --git a/nix/configurations/hetzner_benchmark.nix b/nix/configurations/hetzner_benchmark.nix
index d8235a48..3f84df39 100644
--- a/nix/configurations/hetzner_benchmark.nix
+++ b/nix/configurations/hetzner_benchmark.nix
@@ -57,6 +57,7 @@ in
     ./hetzner_benchmark/nixos/hardware-configuration.nix
     ./hetzner_benchmark/nixos/misc.nix
     ./hetzner_benchmark/nixos/programs.nix
+    ./hetzner_benchmark/nixos/builder.nix
 
     ../nixosModules/common/fish.nix
     ../nixosModules/common/disable-command-not-found.nix
diff --git a/nix/configurations/hetzner_benchmark/nixos/builder.nix b/nix/configurations/hetzner_benchmark/nixos/builder.nix
new file mode 100644
index 00000000..c8191c8d
--- /dev/null
+++ b/nix/configurations/hetzner_benchmark/nixos/builder.nix
@@ -0,0 +1,31 @@
+# https://nix.dev/tutorials/nixos/distributed-builds-setup.html
+{ config, ... }:
+{
+  users.users.remotebuild = {
+    isSystemUser = true;
+    group = "remotebuild";
+    useDefaultShell = true;
+
+    openssh.authorizedKeys.keys = config.users.users.root.openssh.authorizedKeys.keys;
+  };
+
+  users.groups.remotebuild = { };
+  nix = {
+    nrBuildUsers = 64; # defaults to 32
+    settings = {
+      trusted-users = [ "remotebuild" ];
+
+      min-free = 50 * 1024 * 1024 * 1024; # start gc when < 10 GB is available
+      max-free = 100 * 1024 * 1024 * 1024; # stop gc when 20 GB is available
+
+      max-jobs = "auto";
+      cores = 0;
+    };
+  };
+
+  systemd.services.nix-daemon.serviceConfig = {
+    MemoryAccounting = true;
+    MemoryMax = "90%";
+    OOMScoreAdjust = 500;
+  };
+}