update inventory implementation

clanModules/borgbackup/roles/server.nix

@@ -0,0 +1,45 @@
+{ config, lib, ... }:
+let
+  clanDir = config.clan.core.clanDir;
+  machineDir = clanDir + "/machines/";
+  inherit (config.clan.core) machineName;
+  instances = config.clan.inventory.borgbackup;
+
+  # roles = { ${role_name} :: { machines :: [string] } }
+  allClients = lib.foldlAttrs (
+    acc: _instanceName: instanceConfig:
+    acc
+    ++ (
+      if builtins.elem machineName instanceConfig.roles.server.machines then
+        instanceConfig.roles.client.machines
+      else
+        [ ]
+    )
+  ) [ ] instances;
+in
+{
+  config.services.borgbackup.repos =
+    let
+      filteredMachines = allClients;
+
+      borgbackupIpMachinePath = machines: machineDir + machines + "/facts/borgbackup.ssh.pub";
+      machinesMaybeKey = builtins.map (
+        machine:
+        let
+          fullPath = borgbackupIpMachinePath machine;
+        in
+        if builtins.pathExists fullPath then machine else null
+      ) filteredMachines;
+
+      machinesWithKey = lib.filter (x: x != null) machinesMaybeKey;
+
+      hosts = builtins.map (machine: {
+        name = machine;
+        value = {
+          path = "/var/lib/borgbackup/${machine}";
+          authorizedKeys = [ (builtins.readFile (borgbackupIpMachinePath machine)) ];
+        };
+      }) machinesWithKey;
+    in
+    if (builtins.listToAttrs hosts) != [ ] then builtins.listToAttrs hosts else { };
+}