Add rtl_433 Prometheus exporter

maintainers/maintainer-list.nix

@@ -9522,6 +9522,12 @@
     githubId = 1069303;
     name = "Kim Simmons";
   };
+  zopieux = {
+    email = "zopieux@gmail.com";
+    github = "zopieux";
+    githubId = 81353;
+    name = "Alexandre Macabies";
+  };
   zowoq = {
     email = "59103226+zowoq@users.noreply.github.com";
     github = "zowoq";

nixos/modules/hardware/rtl-sdr.nix

@@ -0,0 +1,20 @@
+{ config, lib, pkgs, ... }:
+
+let
+  cfg = config.hardware.rtl-sdr;
+
+in {
+  options.hardware.rtl-sdr = {
+    enable = lib.mkEnableOption ''
+      Enables rtl-sdr udev rules and ensures 'plugdev' group exists.
+      This is a prerequisite to using devices supported by rtl-sdr without
+      being root, since rtl-sdr USB descriptors will be owned by plugdev
+      through udev.
+    '';
+  };
+
+  config = lib.mkIf cfg.enable {
+    services.udev.packages = [ pkgs.rtl-sdr ];
+    users.groups.plugdev = {};
+  };
+}

nixos/modules/module-list.nix

@@ -59,6 +59,7 @@
   ./hardware/pcmcia.nix
   ./hardware/printers.nix
   ./hardware/raid/hpsa.nix
+  ./hardware/rtl-sdr.nix
   ./hardware/steam-hardware.nix
   ./hardware/system-76.nix
   ./hardware/tuxedo-keyboard.nix

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

@@ -42,6 +42,7 @@ let
     "postgres"
     "redis"
     "rspamd"
+    "rtl_433"
     "snmp"
     "surfboard"
     "tor"
@@ -226,6 +227,8 @@ in
     services.prometheus.exporters.minio.minioAccessSecret = mkDefault config.services.minio.secretKey;
   })] ++ [(mkIf config.services.rspamd.enable {
     services.prometheus.exporters.rspamd.url = mkDefault "http://localhost:11334/stat";
+  })] ++ [(mkIf config.services.prometheus.exporters.rtl_433.enable {
+    hardware.rtl-sdr.enable = mkDefault true;
   })] ++ [(mkIf config.services.nginx.enable {
     systemd.services.prometheus-nginx-exporter.after = [ "nginx.service" ];
     systemd.services.prometheus-nginx-exporter.requires = [ "nginx.service" ];

nixos/modules/services/monitoring/prometheus/exporters/rtl_433.nix

@@ -0,0 +1,78 @@
+{ config, lib, pkgs, options }:
+
+let
+  cfg = config.services.prometheus.exporters.rtl_433;
+in
+{
+  port = 9550;
+
+  extraOpts = let
+    mkMatcherOptionType = field: description: with lib.types;
+      listOf (submodule {
+        options = {
+          name = lib.mkOption {
+            type = str;
+            description = "Name to match.";
+          };
+          "${field}" = lib.mkOption {
+            type = int;
+            inherit description;
+          };
+          location = lib.mkOption {
+            type = str;
+            description = "Location to match.";
+          };
+        };
+      });
+  in
+  {
+    rtl433Flags = lib.mkOption {
+      type = lib.types.str;
+      default = "-C si";
+      example = "-C si -R 19";
+      description = ''
+        Flags passed verbatim to rtl_433 binary.
+        Having <literal>-C si</literal> (the default) is recommended since only Celsius temperatures are parsed.
+      '';
+    };
+    channels = lib.mkOption {
+      type = mkMatcherOptionType "channel" "Channel to match.";
+      default = [];
+      example = [
+        { name = "Acurite"; channel = 6543; location = "Kitchen"; }
+      ];
+      description = ''
+        List of channel matchers to export.
+      '';
+    };
+    ids = lib.mkOption {
+      type = mkMatcherOptionType "id" "ID to match.";
+      default = [];
+      example = [
+        { name = "Nexus"; id = 1; location = "Bedroom"; }
+      ];
+      description = ''
+        List of ID matchers to export.
+      '';
+    };
+  };
+
+  serviceOpts = {
+    serviceConfig = {
+      # rtl-sdr udev rules make supported USB devices +rw by plugdev.
+      SupplementaryGroups = "plugdev";
+      ExecStart = let
+        matchers = (map (m:
+          "--channel_matcher '${m.name},${toString m.channel},${m.location}'"
+        ) cfg.channels) ++ (map (m:
+          "--id_matcher '${m.name},${toString m.id},${m.location}'"
+        ) cfg.ids); in ''
+        ${pkgs.prometheus-rtl_433-exporter}/bin/rtl_433_prometheus \
+          -listen ${cfg.listenAddress}:${toString cfg.port} \
+          -subprocess "${pkgs.rtl_433}/bin/rtl_433 -F json ${cfg.rtl433Flags}" \
+          ${lib.concatStringsSep " \\\n  " matchers} \
+          ${lib.concatStringsSep " \\\n  " cfg.extraFlags}
+      '';
+    };
+  };
+}

nixos/tests/prometheus-exporters.nix

@@ -536,6 +536,37 @@ let
       '';
     };
 
+    rtl_433 = {
+      exporterConfig = {
+        enable = true;
+      };
+      metricProvider = {
+        # Mock rtl_433 binary to return a dummy metric stream.
+        nixpkgs.overlays = [ (self: super: {
+          rtl_433 = self.runCommand "rtl_433" {} ''
+            mkdir -p "$out/bin"
+            cat <<EOF > "$out/bin/rtl_433"
+            #!/bin/sh
+            while true; do
+              printf '{"time" : "2020-04-26 13:37:42", "model" : "zopieux", "id" : 55, "channel" : 3, "temperature_C" : 18.000}\n'
+              sleep 4
+            done
+            EOF
+            chmod +x "$out/bin/rtl_433"
+          '';
+        }) ];
+      };
+      exporterTest = ''
+        wait_for_unit("prometheus-rtl_433-exporter.service")
+        wait_for_open_port(9550)
+        wait_until_succeeds(
+            "curl -sSf localhost:9550/metrics | grep -q '{}'".format(
+                'rtl_433_temperature_celsius{channel="3",id="55",location="",model="zopieux"} 18'
+            )
+        )
+      '';
+    };
+
     snmp = {
       exporterConfig = {
         enable = true;

pkgs/applications/radio/rtl-sdr/default.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchgit, cmake, pkgconfig, libusb1 }:
+{ stdenv, fetchgit, fetchpatch, cmake, pkgconfig, libusb1 }:
 
 stdenv.mkDerivation rec {
   pname = "rtl-sdr";
@@ -10,6 +10,12 @@ stdenv.mkDerivation rec {
     sha256 = "0lmvsnb4xw4hmz6zs0z5ilsah5hjz29g1s0050n59fllskqr3b8k";
   };
 
+  patches = [ (fetchpatch {
+    name = "hardened-udev-rules.patch";
+    url = "https://osmocom.org/projects/rtl-sdr/repository/revisions/b2814731563be4d5a0a68554ece6454a2c63af12/diff?format=diff";
+    sha256 = "0ns740s2rys4glq4la4bh0sxfv1mn61yfjns2yllhx70rsb2fqrn";
+  }) ];
+
   nativeBuildInputs = [ pkgconfig cmake ];
   buildInputs = [ libusb1 ];
 

pkgs/servers/monitoring/prometheus/rtl_433-exporter.nix

@@ -0,0 +1,26 @@
+{ lib, buildGoModule, fetchFromGitHub, bash, nixosTests }:
+
+buildGoModule rec {
+  pname = "rtl_433-exporter";
+  version = "0.1";
+
+  src = fetchFromGitHub {
+    owner = "mhansen";
+    repo = "rtl_433_prometheus";
+    rev = "v${version}";
+    sha256 = "1998gvfa5310bxhi6kfv8bn99369dxph3pwrpp335997b25lc2w2";
+  };
+
+  postPatch = "substituteInPlace rtl_433_prometheus.go --replace /bin/bash ${bash}/bin/bash";
+
+  vendorSha256 = "03mnmzq72844hzyw7iq5g4gm1ihpqkg4i9dgj2yln1ghwk843hq6";
+
+  passthru.tests = { inherit (nixosTests.prometheus-exporters) rtl_433; };
+
+  meta = with lib; {
+    description = "Prometheus time-series DB exporter for rtl_433 433MHz radio packet decoder";
+    homepage = "https://github.com/mhansen/rtl_433_prometheus";
+    license = licenses.mit;
+    maintainers = with maintainers; [ zopieux ];
+  };
+}

pkgs/top-level/all-packages.nix

@@ -17012,6 +17012,7 @@ in
   prometheus-pushgateway = callPackage ../servers/monitoring/prometheus/pushgateway.nix { };
   prometheus-redis-exporter = callPackage ../servers/monitoring/prometheus/redis-exporter.nix { };
   prometheus-rabbitmq-exporter = callPackage ../servers/monitoring/prometheus/rabbitmq-exporter.nix { };
+  prometheus-rtl_433-exporter = callPackage ../servers/monitoring/prometheus/rtl_433-exporter.nix { };
   prometheus-snmp-exporter = callPackage ../servers/monitoring/prometheus/snmp-exporter.nix { };
   prometheus-tor-exporter = callPackage ../servers/monitoring/prometheus/tor-exporter.nix { };
   prometheus-statsd-exporter = callPackage ../servers/monitoring/prometheus/statsd-exporter.nix { };