nixos/nixops-dns: init (#34511)

nixos/modules/module-list.nix

@@ -510,6 +510,7 @@
   ./services/networking/ngircd.nix
   ./services/networking/nghttpx/default.nix
   ./services/networking/nix-serve.nix
+  ./services/networking/nixops-dns.nix
   ./services/networking/nntp-proxy.nix
   ./services/networking/nsd.nix
   ./services/networking/ntopng.nix

nixos/modules/services/networking/nixops-dns.nix

@@ -0,0 +1,79 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+let
+  pkg = pkgs.nixops-dns;
+  cfg = config.services.nixops-dns;
+in
+
+{
+  options = {
+    services.nixops-dns = {
+      enable = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          Whether to enable the nixops-dns resolution
+          of NixOps virtual machines via dnsmasq and fake domain name.
+        '';
+      };
+
+      user = mkOption {
+        type = types.str;
+        description = ''
+          The user the nixops-dns daemon should run as.
+          This should be the user, which is also used for nixops and
+          have the .nixops directory in its home.
+        '';
+      };
+
+      domain = mkOption {
+        type = types.str;
+        description = ''
+          Fake domain name to resolve to NixOps virtual machines.
+
+          For example "ops" will resolve "vm.ops".
+        '';
+        example = "ops";
+        default = "ops";
+      };
+
+      dnsmasq = mkOption {
+        type = types.bool;
+        default = true;
+        description = ''
+          Enable dnsmasq forwarding to nixops-dns. This allows to use
+          nixops-dns for `services.nixops-dns.domain` resolution
+          while forwarding the rest of the queries to original resolvers.
+        '';
+      };
+
+    };
+  };
+
+  config = mkIf cfg.enable {
+    systemd.services.nixops-dns = {
+      description = "nixops-dns: DNS server for resolving NixOps machines";
+      wantedBy = [ "multi-user.target" ];
+
+      serviceConfig = {
+        Type = "simple";
+        User = cfg.user;
+        ExecStart="${pkg}/bin/nixops-dns --domain=.${cfg.domain}";
+      };
+    };
+
+    services.dnsmasq = mkIf cfg.dnsmasq {
+      enable = true;
+      resolveLocalQueries = true;
+      servers = [
+        "/${cfg.domain}/127.0.0.1#5300"
+      ];
+      extraConfig = ''
+        bind-interfaces
+        listen-address=127.0.0.1
+      '';
+    };
+
+  };
+}