From 6a080b2319ecd8af06f63ddf57b318196324634c Mon Sep 17 00:00:00 2001
From: aaron <aaron@0x29a.ch>
Date: Fri, 2 Oct 2026 16:39:53 +0200
Subject: [PATCH] feature(boot): attatch /tmp to tmpfs, but keep nix build in
 /var/tmp

---
 modules/nixos/bootloader.nix | 6 ++++++
 modules/nixos/settings.nix   | 3 +++
 2 files changed, 9 insertions(+)

diff --git a/modules/nixos/bootloader.nix b/modules/nixos/bootloader.nix
index 0afe135..2880888 100644
--- a/modules/nixos/bootloader.nix
+++ b/modules/nixos/bootloader.nix
@@ -24,6 +24,12 @@
   boot.kernelPackages = pkgs.linuxPackages_latest;
   boot.consoleLogLevel = 2;
 
+  # /tmp in RAM, nix builds go to /var/tmp instead (see settings.nix)
+  boot.tmp = {
+    useTmpfs = true;
+    tmpfsSize = "50%";
+  };
+
   # Add boot-related packages
   environment.systemPackages = with pkgs; [
     efibootmgr
diff --git a/modules/nixos/settings.nix b/modules/nixos/settings.nix
index 2f46fe7..01d1d85 100644
--- a/modules/nixos/settings.nix
+++ b/modules/nixos/settings.nix
@@ -27,6 +27,9 @@
     };
   };
 
+  # build on disk, big builds would fill the /tmp tmpfs
+  systemd.services.nix-daemon.environment.TMPDIR = "/var/tmp";
+
   # steam, protonvpn, discord, etc.
   nixpkgs.config.allowUnfree = true;
 
-- 
2.52.0