test for locan DNS resolution in machine hosting leng (#78)

This adds a failing test to keep track of progress to hopefully resolve_
#75

flake.nix

@@ -74,6 +74,8 @@
           systemctl-start = pkgs.callPackage ./nixos-tests/systemctl-start.nix { inherit self; };
           custom-dns = pkgs.callPackage ./nixos-tests/custom-dns.nix { inherit self; };
           doh-upstream = pkgs.callPackage ./nixos-tests/doh-upstream.nix { inherit self; };
+          # test fails, see https://github.com/cottand/leng/issues/75
+          #local-resolution = pkgs.callPackage ./nixos-tests/local-resolution.nix { inherit self; };
         };
 
       }))

nixos-tests/local-resolution.nix

@@ -0,0 +1,41 @@
+{ self, pkgs, home-manager, ... }:
+let
+  nixpkgs = self.inputs.nixpkgs;
+in
+(nixpkgs.lib.nixos.runTest {
+  hostPkgs = pkgs;
+  defaults.documentation.enable = false;
+  node.specialArgs = { inherit self; };
+
+  name = "leng-local-resolution";
+
+  nodes = {
+    server = { config, pkgs, ... }: {
+      imports = [ self.nixosModules.default ];
+      environment.systemPackages = [ pkgs.dig ];
+      networking.firewall.allowedUDPPorts = [ 53 ];
+      networking.nameservers = [ "127.0.0.1" ];
+
+      services.leng.enable = true;
+      services.leng.configuration = {
+        blocking.sourcesStore = "/tmp";
+        customdnsrecords = [
+          "example.com    IN A   1.2.3.4"
+        ];
+      };
+    };
+  };
+
+  testScript =
+    ''
+      start_all()
+
+      server.wait_for_unit("leng", timeout=10)
+      server.wait_for_open_port(53)
+
+      server.succeed(
+        "dig example.com"
+      )
+    '';
+
+}).config.result