update inventory implementation

clanModules/borgbackup/roles/client.nix

@@ -0,0 +1,30 @@
+{ config, lib, ... }:
+let
+  instances = config.clan.inventory.borgbackup;
+  # roles = { ${role_name} :: { machines :: [string] } }
+  allServers = lib.foldlAttrs (
+    acc: _instanceName: instanceConfig:
+    acc
+    ++ (
+      if builtins.elem machineName instanceConfig.roles.client.machines then
+        instanceConfig.roles.server.machines
+      else
+        [ ]
+    )
+  ) [ ] instances;
+
+  inherit (config.clan.core) machineName;
+in
+{
+  config.clan.borgbackup.destinations =
+    let
+
+      destinations = builtins.map (serverName: {
+        name = serverName;
+        value = {
+          repo = "borg@${serverName}:/var/lib/borgbackup/${machineName}";
+        };
+      }) allServers;
+    in
+    (builtins.listToAttrs destinations);
+}