From 33cab3051153ed77663474801aaff4a4c3287124 Mon Sep 17 00:00:00 2001
From: "quentin@aristote.fr" <quentin@aristote.fr>
Date: Sun, 8 Dec 2024 23:02:44 +0100
Subject: nix: enable remote building

---
 config/default.nix           |  2 +-
 config/nix.nix               | 31 -------------------------------
 config/nix/default.nix       | 33 +++++++++++++++++++++++++++++++++
 config/nix/remote-builds.nix | 30 ++++++++++++++++++++++++++++++
 4 files changed, 64 insertions(+), 32 deletions(-)
 delete mode 100644 config/nix.nix
 create mode 100644 config/nix/default.nix
 create mode 100644 config/nix/remote-builds.nix

diff --git a/config/default.nix b/config/default.nix
index dd22e26..4078e47 100644
--- a/config/default.nix
+++ b/config/default.nix
@@ -5,7 +5,7 @@
     ./boot.nix
     ./environment.nix
     ./networking.nix
-    ./nix.nix
+    ./nix
     ./services
     ./users.nix
   ];
diff --git a/config/nix.nix b/config/nix.nix
deleted file mode 100644
index a3d2da2..0000000
--- a/config/nix.nix
+++ /dev/null
@@ -1,31 +0,0 @@
-{lib, ...}: {
-  personal.nix = {
-    enable = true;
-    autoUpgrade = {
-      enable = true;
-      autoUpdateInputs = ["nixpkgs" "nixpkgs-unstable"];
-    };
-    gc.enable = true;
-    flake = "git+file:///etc/nixos/";
-  };
-  nix.settings.max-jobs = lib.mkDefault 1;
-  nixpkgs.flake = {
-    setNixPath = true;
-    setFlakeRegistry = true;
-  };
-
-  systemd.services.nixos-upgrade = let
-    mkForce = lib.mkOverride 51;
-  in {
-    # restart at most once every hour
-    serviceConfig = {
-      Restart = "on-failure";
-      RestartSec = "5sec";
-      MemoryAccounting = true;
-      MemoryHigh = "1G";
-      MemoryMax = "1.5G";
-    };
-    startLimitBurst = mkForce 1;
-    startLimitIntervalSec = mkForce 3600;
-  };
-}
diff --git a/config/nix/default.nix b/config/nix/default.nix
new file mode 100644
index 0000000..c930095
--- /dev/null
+++ b/config/nix/default.nix
@@ -0,0 +1,33 @@
+{lib, ...}: {
+  imports = [./remote-builds.nix];
+
+  personal.nix = {
+    enable = true;
+    autoUpgrade = {
+      enable = true;
+      autoUpdateInputs = ["nixpkgs" "nixpkgs-unstable"];
+    };
+    gc.enable = true;
+    flake = "git+file:///etc/nixos/";
+  };
+  nix.settings.max-jobs = lib.mkDefault 1;
+  nixpkgs.flake = {
+    setNixPath = true;
+    setFlakeRegistry = true;
+  };
+
+  systemd.services.nixos-upgrade = let
+    mkForce = lib.mkOverride 51;
+  in {
+    # restart at most once every hour
+    serviceConfig = {
+      Restart = "on-failure";
+      RestartSec = "5sec";
+      MemoryAccounting = true;
+      MemoryHigh = "1G";
+      MemoryMax = "1.5G";
+    };
+    startLimitBurst = mkForce 1;
+    startLimitIntervalSec = mkForce 3600;
+  };
+}
diff --git a/config/nix/remote-builds.nix b/config/nix/remote-builds.nix
new file mode 100644
index 0000000..5f23108
--- /dev/null
+++ b/config/nix/remote-builds.nix
@@ -0,0 +1,30 @@
+{...}: {
+  networking.hosts."10.13.42.2" = ["hephaistos.local"];
+  programs.ssh = {
+    extraConfig = ''
+      Host hephaistos.local
+        # Prevent using ssh-agent or another keyfile, useful for testing
+        IdentitiesOnly yes
+        IdentityFile /etc/ssh/nixremote
+        # The weakly privileged user on the remote builder – if not set, 'root' is used – which will hopefully fail
+        User nixremote
+    '';
+    knownHosts."hephaistos.local".publicKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIHvtqi8tziBuviUV8LDK2ddQQUbHdJYB02dgWTK5Olxq";
+  };
+
+  nix = {
+    distributedBuilds = true;
+    buildMachines = [
+      {
+        hostName = "hephaistos.local";
+        system = "x86_64-linux";
+        # Nix custom ssh-variant that avoids lots of "trusted-users" settings pain
+        protocol = "ssh-ng";
+        maxJobs = 4;
+        speedFactor = 4;
+        supportedFeatures = ["nixos-test" "benchmark" "big-parallel" "kvm"];
+        mandatoryFeatures = [];
+      }
+    ];
+  };
+}
-- 
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