modules/nixos: small nit fixes

Moved the `/var/tmp` configuration for the Nix daemon from the `/tmp` module to the nix module. Removed the desire for a zram writeback device since it would have no benefit on a tmpfs system anyways, unless I dedicated a drive to it. Lastly, changed the systemd-boot module to use `rec` in an isolated block.
Frontear · Jan 9, 2025 · 44c1976 · 44c1976
1 parent 4657d3a
commit 44c1976
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Showing 4 changed files with 9 additions and 7 deletions.
diff --git a/modules/nixos/programs/nix/module.nix b/modules/nixos/programs/nix/module.nix
@@ -18,6 +18,13 @@ in {
       # since the build is extremely small and fast, but why not.
       my.toplevel.cachix = [ config.nix.package ];
 
+      # Instruct the daemon to use `/var/tmp` as the TMPDIR instead of `/tmp`.
+      # This is because `/tmp` can be a tmpfs (and honestly should). `/var/tmp`
+      # is designed to contain persistent, yet temporary files, a definition
+      # that fits Nix's usage of the TMPDIR perfectly.
+      my.persist.directories = [ "/var/tmp" ];
+      systemd.services.nix-daemon.environment.TMPDIR = "/var/tmp";
+
       # Use github:viperML/nh as our "nix wrapper" program.
       programs.nh.enable = true;
 

diff --git a/modules/nixos/system/boot/systemd-boot/module.nix b/modules/nixos/system/boot/systemd-boot/module.nix
@@ -25,7 +25,7 @@ in {
         editor = cfg.editor;
       };
     }
-    (lib.mkIf cfg.silent {
+    (lib.mkIf cfg.silent rec {
       # https://wiki.archlinux.org/title/Silent_boot
       boot.consoleLogLevel = 3;
       boot.initrd.verbose = false;
@@ -35,7 +35,7 @@ in {
       boot.kernelParams = [
         "quiet"
         "systemd.show_status=auto"
-        "udev.log_level=${toString config.boot.consoleLogLevel}"
+        "udev.log_level=${toString boot.consoleLogLevel}"
       ];
     })
   ]);

diff --git a/modules/nixos/system/mounts/swap/module.nix b/modules/nixos/system/mounts/swap/module.nix
@@ -26,7 +26,6 @@ in {
         enable = true;
         memoryPercent = 150; # https://unix.stackexchange.com/a/596929
         priority = 100;
-        # TODO: writebackDevice?
       };
     })
   ];

diff --git a/modules/nixos/system/mounts/tmp/module.nix b/modules/nixos/system/mounts/tmp/module.nix
@@ -12,10 +12,6 @@ in {
 
   config = lib.mkMerge [
     (lib.mkIf cfg.enableTmpfs {
-      # Force the Nix builder into a sane TMPDIR
-      my.persist.directories = [ "/var/tmp" ];
-      systemd.services.nix-daemon.environment.TMPDIR = "/var/tmp";
-
       # Use tmpfs for /tmp as it's just easier to use.
       # Not using this means that cleaning on boot can
       # take a few seconds, which is wasteful.