From d48883ca9bd4d59ed0eb949c7148743268f192f9 Mon Sep 17 00:00:00 2001
From: Kristoffer Dalby <kristoffer@tailscale.com>
Date: Mon, 28 Sep 2026 13:35:35 +0000
Subject: [PATCH] nix: write split DNS where headscale reads it

module.nix emitted dns.split; headscale reads dns.nameservers.split, so the
typed option was silently ignored. Old path now asserts.
---
 CHANGELOG.md   |  1 +
 nix/module.nix | 21 +++++++++++----------
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c2e82de1..ada2953e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -90,6 +90,7 @@ removed on this schedule:
 #### NixOS module
 
 - `settings.ephemeral_node_inactivity_timeout` is removed; set `settings.node.ephemeral.inactivity_timeout`, which headscale reads instead
+- `settings.dns.split` is removed; headscale never read it, set `settings.dns.nameservers.split`
 
 ### Changes
 
diff --git a/nix/module.nix b/nix/module.nix
index 2233d971..465fa978 100644
--- a/nix/module.nix
+++ b/nix/module.nix
@@ -364,17 +364,17 @@ in
                     List of nameservers to pass to Tailscale clients.
                   '';
                 };
-              };
 
-              split = lib.mkOption {
-                type = lib.types.attrsOf (lib.types.listOf lib.types.str);
-                default = { };
-                description = ''
-                  Split DNS configuration (map of domains and which DNS server to use for each).
-                  See <https://tailscale.com/docs/reference/dns-in-tailscale>.
-                '';
-                example = {
-                  "foo.bar.com" = [ "1.1.1.1" ];
+                split = lib.mkOption {
+                  type = lib.types.attrsOf (lib.types.listOf lib.types.str);
+                  default = { };
+                  description = ''
+                    Split DNS configuration (map of domains and which DNS server to use for each).
+                    See <https://tailscale.com/docs/reference/dns-in-tailscale>.
+                  '';
+                  example = {
+                    "foo.bar.com" = [ "1.1.1.1" ];
+                  };
                 };
               };
 
@@ -688,6 +688,7 @@ in
       (assertRemovedOption [ "settings" "db_port" ] "Use `database.postgres.port` instead.")
       (assertRemovedOption [ "settings" "db_type" ] "Use `database.type` instead.")
       (assertRemovedOption [ "settings" "db_user" ] "Use `database.postgres.user` instead.")
+      (assertRemovedOption [ "settings" "dns" "split" ] "Use `dns.nameservers.split` instead.")
       (assertRemovedOption [ "settings" "dns_config" ] "Use `dns` instead.")
       (assertRemovedOption [ "settings" "dns_config" "domains" ] "Use `dns.search_domains` instead.")
       (assertRemovedOption [