setup nix-topology

machines/genepi/configuration.nix

@@ -19,6 +19,7 @@
     ./nginx.nix
     ./syncthing.nix
     ./taskchampion.nix
+    ./topology.nix
 
     ../../system
     ../../modules/borgbackup.nix

machines/genepi/topology.nix

@@ -0,0 +1,24 @@
+{ config, ... }:
+let
+  inherit (config.lib.topology)
+    mkConnection
+    ;
+in
+{
+  topology.self = {
+    hardware.info = "Raspberry Pi 4B";
+    interfaces = {
+      tailscale0 = {
+        type = "wireguard";
+        network = "tailscale";
+      };
+      enp1s0 = {
+        type = "ethernet";
+        network = "home";
+        physicalConnections = [
+          (mkConnection "cassoulet" "eth1")
+        ];
+      };
+    };
+  };
+}