added prometheus-borgmatic-exporter module

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

@@ -27,6 +27,7 @@ let
     "bird"
     "bitcoin"
     "blackbox"
+    "borgmatic"
     "buildkite-agent"
     "collectd"
     "deluge"

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

@@ -0,0 +1,34 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+
+let
+  cfg = config.services.prometheus.exporters.borgmatic;
+in
+{
+  port = 9996;
+  extraOpts.configFile = lib.mkOption {
+    type = lib.types.path;
+    default = "/etc/borgmatic/config.yaml";
+    description = ''
+      The path to the borgmatic config file
+    '';
+  };
+
+  serviceOpts = {
+    serviceConfig = {
+      DynamicUser = false;
+      ProtectSystem = false;
+      ProtectHome = lib.mkForce false;
+      ExecStart = ''
+        ${pkgs.prometheus-borgmatic-exporter}/bin/borgmatic-exporter run \
+          --port ${toString cfg.port} \
+          --config ${toString cfg.configFile} \
+          ${lib.concatMapStringsSep " " (f: lib.escapeShellArg f) cfg.extraFlags}
+      '';
+    };
+  };
+}

nixos/tests/prometheus-exporters.nix

@@ -177,6 +177,26 @@ let
       '';
     };
 
+    borgmatic = {
+      exporterConfig = {
+        enable = true;
+        user = "root";
+      };
+      metricProvider = {
+        services.borgmatic.enable = true;
+        services.borgmatic.settings.source_directories = [ "/home" ];
+        services.borgmatic.settings.repositories = [ { label = "local"; path = "/var/backup"; } ];
+        services.borgmatic.settings.keep_daily = 10;
+      };
+      exporterTest = ''
+        succeed("borgmatic rcreate -e none")
+        succeed("borgmatic")
+        wait_for_unit("prometheus-borgmatic-exporter.service")
+        wait_for_open_port(9996)
+        succeed("curl -sSf localhost:9996/metrics | grep 'borg_total_backups{repository=\"/var/backup\"} 1'")
+      '';
+    };
+
     collectd = {
       exporterConfig = {
         enable = true;