nixos/prometheus/storagebox: Init module

nixos/doc/manual/release-notes/rl-2511.section.md

···
 
 - [SuiteNumérique Meet](https://github.com/suitenumerique/meet) is an open source alternative to Google Meet and Zoom powered by LiveKit: HD video calls, screen sharing, and chat features. Built with Django and React. Available as [services.lasuite-meet](#opt-services.lasuite-meet.enable).
 
+- [Prometheus Storagebox Exporter](https://github.com/fleaz/prometheus-storagebox-exporter), a Prometheus exporter for Hetzner storage boxes.
+
 - [lemurs](https://github.com/coastalwhite/lemurs), a customizable TUI display/login manager. Available at [services.displayManager.lemurs](#opt-services.displayManager.lemurs.enable).
 
 - [paisa](https://github.com/ananthakumaran/paisa), a personal finance tracker and dashboard. Available as [services.paisa](#opt-services.paisa.enable).

nixos/modules/services/monitoring/prometheus/exporters.nix

···
         "snmp"
         "sql"
         "statsd"
+        "storagebox"
         "surfboard"
         "systemd"
         "tibber"

nixos/modules/services/monitoring/prometheus/exporters/storagebox.nix

···
+{
+  config,
+  lib,
+  pkgs,
+  options,
+  ...
+}:
+
+let
+  cfg = config.services.prometheus.exporters.storagebox;
+  inherit (lib) mkPackageOption;
+in
+{
+  port = 9509;
+  extraOpts = {
+    package = mkPackageOption pkgs "prometheus-storagebox-exporter" { };
+    tokenFile = lib.mkOption {
+      type = lib.types.pathWith {
+        inStore = false;
+        absolute = true;
+      };
+      description = "File that contains the Hetzner API token to use.";
+    };
+
+  };
+  serviceOpts = {
+    after = [ "network.target" ];
+    wantedBy = [ "multi-user.target" ];
+    script = ''
+      export HETZNER_TOKEN=$(< "''${CREDENTIALS_DIRECTORY}/token")
+      exec ${lib.getExe cfg.package}
+    '';
+
+    environment = {
+      LISTEN_ADDR = "${toString cfg.listenAddress}:${toString cfg.port}";
+    };
+
+    serviceConfig = {
+      DynamicUser = true;
+      Restart = "always";
+      RestartSec = "10s";
+      LoadCredential = [
+        "token:${cfg.tokenFile}"
+      ];
+    };
+  };
+}

nixos/tests/prometheus-exporters.nix

···
       '';
     };
 
+    storagebox = {
+      exporterConfig = {
+        enable = true;
+        tokenFile = "/tmp/faketoken";
+      };
+      exporterTest = ''
+        succeed(
+          'echo faketoken > /tmp/faketoken'
+        )
+        wait_for_unit("prometheus-storagebox-exporter.service")
+        wait_for_open_port(9509)
+        succeed("curl -sSf localhost:9509/metrics | grep 'process_open_fds'")
+      '';
+    };
+
     snmp = {
       exporterConfig = {
         enable = true;