First version.

modules/default.nix

@@ -0,0 +1,45 @@
+{ pkgs, ... }: {
+  systemd.services =
+    let
+      service-1 = "service-1";
+      service-2 = "service-2";
+    in
+    {
+      ${service-1} = {
+        enable = true;
+        description = service-1;
+        wants = [ "network-online.target" ];
+        after = [
+          "network-online.target"
+          "avahi-daemon.service"
+          "chrony.service"
+          "nss-lookup.target"
+          "tinc.service"
+          "pulseaudio.service"
+        ];
+        serviceConfig = {
+          Type = "oneshot";
+          RemainAfterExit = true;
+          script = ''
+            true
+          '';
+          ExecReload = "true";
+        };
+        wantedBy = [ "multi-user.target" ];
+      };
+
+      ${service-2} = {
+        enable = true;
+        description = service-2;
+        serviceConfig = {
+          Type = "simple";
+        };
+        partOf = [ "${service-1}.service" ];
+        wantedBy = [ "${service-1}.service" ];
+
+        script = ''
+          true
+        '';
+      };
+    };
+}