modules/hostname.nix

@@ -1,7 +1,6 @@
 { lib, pkgs, config, ...}:
 let
   inherit (lib) mkOption types;
-  inherit (pkgs.liminix.services) oneshot;
 in {
   options = {
     hostname = mkOption {
@@ -12,12 +11,21 @@ in {
       default = "liminix";
       type = types.nonEmptyStr;
     };
-  };
-  config = {
-    services.hostname = oneshot {
-      name = "hostname-${builtins.substring 0 12 (builtins.hashString "sha256" config.hostname)}";
-      up = "echo ${config.hostname} > /proc/sys/kernel/hostname";
-      down = "true";
+    hostname-script = mkOption {
+      description = ''
+        Script that outputs the system hostname on stdin.
+      '';
+      default = pkgs.writeScript "hostname-gen" ''
+        #!/bin/sh
+        echo ${config.hostname}
+      '';
+      defaultText = ''
+        pkgs.writeScript "hostname-gen" '''
+        #!/bin/sh
+        echo ''${config.hostname}
+      '''
+      '';
+      type = types.package;
     };
   };
 }

modules/s6/default.nix

@@ -30,6 +30,8 @@ let
     installPhase = ''
       mkdir $out
       cp -r $src $out/scripts
+      substituteInPlace $out/scripts/rc.init \
+        --replace-fail 'config.hostname' "${config.hostname-script}"
       chmod -R +w $out
     '';
   };

modules/s6/scripts/rc.init

@@ -36,6 +36,7 @@ fi
 ### (replace /run/service with your scandir)
 s6-rc-init -d -c /etc/s6-rc/compiled /run/service
 
+config.hostname > /proc/sys/kernel/hostname
 
 ### 2. Starting the wanted set of services
 ### This is also called every time you change runlevels with telinit.