write own bacula config file since the upstream one is broken

modules/bacula.nix

@@ -1,4 +1,33 @@
-{ config, ... }:
+{ pkgs, config, lib, ... }:
+with lib;
+
+let
+  # We write a custom config file because the upstream config has some flaws
+  fd_cfg = config.services.bacula-fd;
+  fd_conf = pkgs.writeText "bacula-fd.conf" ''
+    Client {
+      Name = ${fd_cfg.name}
+      FDPort = ${toString fd_cfg.port}
+      WorkingDirectory = /var/lib/bacula
+      Pid Directory = /run
+      ${fd_cfg.extraClientConfig}
+    }
+
+    ${concatStringsSep "\n" (mapAttrsToList (name: value: ''
+    Director {
+      Name = ${name}
+      Password = ${value.password}
+      Monitor = ${value.monitor}
+    }
+    '') fd_cfg.director)}
+
+    Messages {
+      Name = Standard;
+      syslog = all, !skipped, !restored
+      ${fd_cfg.extraMessagesConfig}
+    }
+  '';
+in
 {
   sops.secrets = {
     "bacula/password".owner = "bacula";
@@ -35,4 +64,5 @@
       Password = @${config.sops.secrets."bacula/password".path}
     }
   '';
+  systemd.services.bacula-fd.serviceConfig.ExecStart = lib.mkForce "${pkgs.bacula}/sbin/bacula-fd -f -u root -g bacula -c ${fd_conf}";
 }