nixos/kubernetes: allow setting multiple kubelet dns resolvers (#338523)

nixos/doc/manual/release-notes/rl-2411.section.md

@@ -119,6 +119,8 @@
 
 - `grafana` has been updated to version 11.1. This version doesn't support setting `http_addr` to a hostname anymore, an IP address is expected.
 
+- `services.kubernetes.kubelet.clusterDns` now accepts a list of DNS resolvers rather than a single string, bringing the module more in line with the upstream Kubelet configuration schema.
+
 - `wstunnel` has had a major version upgrade that entailed rewriting the program in Rust.
   The module was updated to accommodate for breaking changes.
   Breaking changes to the module API were minimised as much as possible,

nixos/modules/services/cluster/kubernetes/kubelet.nix

@@ -64,7 +64,7 @@ let
   } // lib.optionalAttrs (cfg.tlsCertFile != null)  { tlsCertFile = cfg.tlsCertFile; }
     // lib.optionalAttrs (cfg.tlsKeyFile != null)   { tlsPrivateKeyFile = cfg.tlsKeyFile; }
     // lib.optionalAttrs (cfg.clusterDomain != "")  { clusterDomain = cfg.clusterDomain; }
-    // lib.optionalAttrs (cfg.clusterDns != "")     { clusterDNS = [ cfg.clusterDns ] ; }
+    // lib.optionalAttrs (cfg.clusterDns != [])     { clusterDNS = cfg.clusterDns; }
     // lib.optionalAttrs (cfg.featureGates != {})   { featureGates = cfg.featureGates; }
   ));
 
@@ -112,8 +112,8 @@ in
 
     clusterDns = mkOption {
       description = "Use alternative DNS.";
-      default = "10.1.0.1";
-      type = str;
+      default = [ "10.1.0.1" ];
+      type = listOf str;
     };
 
     clusterDomain = mkOption {