Merge pull request #115185 from Ma27/knot-exporter

prometheus-knot-exporter: init at 2021-01-30; minor module improvements

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

@@ -3,7 +3,7 @@
 let
   inherit (lib) concatStrings foldl foldl' genAttrs literalExample maintainers
                 mapAttrsToList mkDefault mkEnableOption mkIf mkMerge mkOption
-                optional types;
+                optional types mkOptionDefault flip attrNames;
 
   cfg = config.services.prometheus.exporters;
 
@@ -32,6 +32,7 @@ let
     "fritzbox"
     "json"
     "keylight"
+    "knot"
     "lnd"
     "mail"
     "mikrotik"
@@ -65,7 +66,7 @@ let
   mkExporterOpts = ({ name, port }: {
     enable = mkEnableOption "the prometheus ${name} exporter";
     port = mkOption {
-      type = types.int;
+      type = types.port;
       default = port;
       description = ''
         Port to listen on.
@@ -93,9 +94,8 @@ let
       '';
     };
     firewallFilter = mkOption {
-      type = types.str;
-      default = "-p tcp -m tcp --dport ${toString cfg.${name}.port}";
-      defaultText = "-p tcp -m tcp --dport ${toString port}";
+      type = types.nullOr types.str;
+      default = null;
       example = literalExample ''
         "-i eth0 -p tcp -m tcp --dport ${toString port}"
       '';
@@ -123,12 +123,14 @@ let
 
   mkSubModule = { name, port, extraOpts, imports }: {
     ${name} = mkOption {
-      type = types.submodule {
+      type = types.submodule [{
         inherit imports;
         options = (mkExporterOpts {
           inherit name port;
         } // extraOpts);
-      };
+      } ({ config, ... }: mkIf config.openFirewall {
+        firewallFilter = mkOptionDefault "-p tcp -m tcp --dport ${toString config.port}";
+      })];
       internal = true;
       default = {};
     };
@@ -233,7 +235,13 @@ in
         Please specify either 'services.prometheus.exporters.sql.configuration' or
           'services.prometheus.exporters.sql.configFile'
       '';
-    } ];
+    } ] ++ (flip map (attrNames cfg) (exporter: {
+      assertion = cfg.${exporter}.firewallFilter != null -> cfg.${exporter}.openFirewall;
+      message = ''
+        The `firewallFilter'-option of exporter ${exporter} doesn't have any effect unless
+        `openFirewall' is set to `true'!
+      '';
+    }));
   }] ++ [(mkIf config.services.minio.enable {
     services.prometheus.exporters.minio.minioAddress  = mkDefault "http://localhost:9000";
     services.prometheus.exporters.minio.minioAccessKey = mkDefault config.services.minio.accessKey;

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

@@ -0,0 +1,50 @@
+{ config, lib, pkgs, options }:
+
+with lib;
+
+let
+  cfg = config.services.prometheus.exporters.knot;
+in {
+  port = 9433;
+  extraOpts = {
+    knotLibraryPath = mkOption {
+      type = types.str;
+      default = "${pkgs.knot-dns.out}/lib/libknot.so";
+      defaultText = "\${pkgs.knot-dns}/lib/libknot.so";
+      description = ''
+        Path to the library of <package>knot-dns</package>.
+      '';
+    };
+
+    knotSocketPath = mkOption {
+      type = types.str;
+      default = "/run/knot/knot.sock";
+      description = ''
+        Socket path of <citerefentry><refentrytitle>knotd</refentrytitle>
+        <manvolnum>8</manvolnum></citerefentry>.
+      '';
+    };
+
+    knotSocketTimeout = mkOption {
+      type = types.int;
+      default = 2000;
+      description = ''
+        Timeout in seconds.
+      '';
+    };
+  };
+  serviceOpts = {
+    serviceConfig = {
+      ExecStart = ''
+        ${pkgs.prometheus-knot-exporter}/bin/knot_exporter \
+          --web-listen-addr ${cfg.listenAddress} \
+          --web-listen-port ${toString cfg.port} \
+          --knot-library-path ${cfg.knotLibraryPath} \
+          --knot-socket-path ${cfg.knotSocketPath} \
+          --knot-socket-timeout ${toString cfg.knotSocketTimeout} \
+          ${concatStringsSep " \\\n  " cfg.extraFlags}
+      '';
+      SupplementaryGroups = [ "knot" ];
+    };
+  };
+}