set hostname before dhcp client runs

modules/hostname.nix

@@ -0,0 +1,19 @@
+{ lib, pkgs, config, ...}:
+let
+  inherit (lib) mkOption types;
+  inherit (pkgs.liminix.services) oneshot;
+in {
+  options = {
+    hostname = mkOption {
+      default = "liminix";
+      type = types.nonEmptyStr;
+    };
+  };
+  config = {
+    services.hostname = oneshot {
+      name = "hostname";
+      up = "echo ${config.hostname} > /proc/sys/kernel/hostname";
+      down = "true";
+    };
+  };
+}