nixos/prometheus-fritz-exporter: init module

nixos/doc/manual/release-notes/rl-2405.section.md

@@ -109,6 +109,8 @@ The pre-existing [services.ankisyncd](#opt-services.ankisyncd.enable) has been m
 
 - [Clevis](https://github.com/latchset/clevis), a pluggable framework for automated decryption, used to unlock encrypted devices in initrd. Available as [boot.initrd.clevis.enable](#opt-boot.initrd.clevis.enable).
 
+- [fritz-exporter](https://github.com/pdreker/fritz_exporter), a Prometheus exporter for extracting metrics from [FRITZ!](https://avm.de/produkte/) devices. Available as [services.prometheus.exporters.fritz](#opt-services.prometheus.exporters.fritz.enable).
+
 - [armagetronad](https://wiki.armagetronad.org), a mid-2000s 3D lightcycle game widely played at iD Tech Camps. You can define multiple servers using `services.armagetronad.<server>.enable`.
 
 - [TuxClocker](https://github.com/Lurkki14/tuxclocker), a hardware control and monitoring program. Available as [programs.tuxclocker](#opt-programs.tuxclocker.enable).

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

@@ -35,6 +35,7 @@ let
     "dovecot"
     "fastly"
     "flow"
+    "fritz"
     "fritzbox"
     "graphite"
     "idrac"

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

@@ -0,0 +1,97 @@
+{ config, lib, pkgs, utils, ... }:
+let
+  inherit (lib) mkOption types mdDoc;
+  cfg = config.services.prometheus.exporters.fritz;
+  yaml = pkgs.formats.yaml { };
+  configFile = yaml.generate "fritz-exporter.yaml" cfg.settings;
+in
+{
+  port = 9787;
+
+  extraOpts = {
+    settings = mkOption {
+      description = mdDoc "Configuration settings for fritz-exporter.";
+      type = types.submodule {
+        freeformType = yaml.type;
+
+        options = {
+          # Pull existing port option into config file.
+          port = mkOption {
+            type = types.port;
+            default = cfg.port;
+            internal = true;
+            visible = false;
+          };
+          # Pull existing listen address option into config file.
+          listen_address = mkOption {
+            type = types.str;
+            default = cfg.listenAddress;
+            internal = true;
+            visible = false;
+          };
+          log_level = mkOption {
+            type = types.enum [ "DEBUG" "INFO" "WARNING" "ERROR" "CRITICAL" ];
+            default = "INFO";
+            description = mdDoc ''
+              Log level to use for the exporter.
+            '';
+          };
+          devices = mkOption {
+            default = [];
+            description = "Fritz!-devices to monitor using the exporter.";
+            type = with types; listOf (submodule {
+              freeformType = yaml.type;
+
+              options = {
+                name = mkOption {
+                  type = types.str;
+                  default = "";
+                  description = mdDoc ''
+                    Name to use for the device.
+                  '';
+                };
+                hostname = mkOption {
+                  type = types.str;
+                  default = "fritz.box";
+                  description = mdDoc ''
+                    Hostname under which the target device is reachable.
+                  '';
+                };
+                username = mkOption {
+                  type = types.str;
+                  description = mdDoc ''
+                    Username to authenticate with the target device.
+                  '';
+                };
+                password_file = mkOption {
+                  type = types.path;
+                  description = mdDoc ''
+                    Path to a file which contains the password to authenticate with the target device.
+                    Needs to be readable by the user the exporter runs under.
+                  '';
+                };
+                host_info = mkOption {
+                  type = types.bool;
+                  description = mdDoc ''
+                    Enable extended host info for this device. *Warning*: This will heavily increase scrape time.
+                  '';
+                  default = false;
+                };
+              };
+            });
+          };
+        };
+      };
+    };
+  };
+
+  serviceOpts = {
+    serviceConfig = {
+      ExecStart = utils.escapeSystemdExecArgs ([
+        (lib.getExe pkgs.fritz-exporter)
+        "--config" configFile
+      ] ++ cfg.extraFlags);
+      DynamicUser = false;
+    };
+  };
+}