nixos/mqtt2influxdb: init module

nixos/modules/module-list.nix

···
   ./services/misc/mediatomb.nix
   ./services/misc/metabase.nix
   ./services/misc/moonraker.nix
+  ./services/misc/mqtt2influxdb.nix
   ./services/misc/n8n.nix
   ./services/misc/nitter.nix
   ./services/misc/nix-gc.nix

nixos/modules/services/misc/mqtt2influxdb.nix

···
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+
+with lib;
+
+let
+  cfg = config.services.mqtt2influxdb;
+  filterNull = filterAttrsRecursive (n: v: v != null);
+  configFile = (pkgs.formats.yaml {}).generate "mqtt2influxdb.config.yaml" (
+    filterNull {
+      inherit (cfg) mqtt influxdb;
+      points = map filterNull cfg.points;
+    }
+  );
+
+  pointType = types.submodule {
+    options = {
+      measurement = mkOption {
+        type = types.str;
+        description = mdDoc "Name of the measurement";
+      };
+      topic = mkOption {
+        type = types.str;
+        description = mdDoc "MQTT topic to subscribe to.";
+      };
+      fields = mkOption {
+        type = types.submodule {
+          options = {
+            value = mkOption {
+              type = types.str;
+              default = "$.payload";
+              description = mdDoc "Value to be picked up";
+            };
+            type = mkOption {
+              type = with types; nullOr str;
+              default = null;
+              description = mdDoc "Type to be picked up";
+            };
+          };
+        };
+        description = mdDoc "Field selector.";
+      };
+      tags = mkOption {
+        type = with types; attrsOf str;
+        default = {};
+        description = mdDoc "Tags applied";
+      };
+    };
+  };
+
+  defaultPoints = [
+    {
+      measurement = "temperature";
+      topic = "node/+/thermometer/+/temperature";
+      fields.value = "$.payload";
+      tags = {
+        id = "$.topic[1]";
+        channel = "$.topic[3]";
+      };
+    }
+    {
+      measurement = "relative-humidity";
+      topic = "node/+/hygrometer/+/relative-humidity";
+      fields.value = "$.payload";
+      tags = {
+        id = "$.topic[1]";
+        channel = "$.topic[3]";
+      };
+    }
+    {
+      measurement = "illuminance";
+      topic = "node/+/lux-meter/0:0/illuminance";
+      fields.value = "$.payload";
+      tags = {
+        id = "$.topic[1]";
+      };
+    }
+    {
+      measurement = "pressure";
+      topic = "node/+/barometer/0:0/pressure";
+      fields.value = "$.payload";
+      tags = {
+        id = "$.topic[1]";
+      };
+    }
+    {
+      measurement = "co2";
+      topic = "node/+/co2-meter/-/concentration";
+      fields.value = "$.payload";
+      tags = {
+        id = "$.topic[1]";
+      };
+    }
+    {
+      measurement = "voltage";
+      topic = "node/+/battery/+/voltage";
+      fields.value = "$.payload";
+      tags = {
+        id = "$.topic[1]";
+      };
+    }
+    {
+      measurement = "button";
+      topic = "node/+/push-button/+/event-count";
+      fields.value = "$.payload";
+      tags = {
+        id = "$.topic[1]";
+        channel = "$.topic[3]";
+      };
+    }
+    {
+      measurement = "tvoc";
+      topic = "node/+/voc-lp-sensor/0:0/tvoc";
+      fields.value = "$.payload";
+      tags = {
+        id = "$.topic[1]";
+      };
+    }
+  ];
+in {
+  options = {
+    services.mqtt2influxdb = {
+      enable = mkEnableOption (mdDoc "BigClown MQTT to InfluxDB bridge.");
+      environmentFiles = mkOption {
+        type = types.listOf types.path;
+        default = [];
+        example = [ "/run/keys/mqtt2influxdb.env" ];
+        description = mdDoc ''
+          File to load as environment file. Environment variables from this file
+          will be interpolated into the config file using envsubst with this
+          syntax: `$ENVIRONMENT` or `''${VARIABLE}`.
+          This is useful to avoid putting secrets into the nix store.
+        '';
+      };
+      mqtt = {
+        host = mkOption {
+          type = types.str;
+          default = "127.0.0.1";
+          description = mdDoc "Host where MQTT server is running.";
+        };
+        port = mkOption {
+          type = types.port;
+          default = 1883;
+          description = mdDoc "MQTT server port.";
+        };
+        username = mkOption {
+          type = with types; nullOr str;
+          default = null;
+          description = mdDoc "Username used to connect to the MQTT server.";
+        };
+        password = mkOption {
+          type = with types; nullOr str;
+          default = null;
+          description = mdDoc ''
+            MQTT password.
+
+            It is highly suggested to use here replacement through
+            environmentFiles as otherwise the password is put world readable to
+            the store.
+          '';
+        };
+        cafile = mkOption {
+          type = with types; nullOr path;
+          default = null;
+          description = mdDoc "Certification Authority file for MQTT";
+        };
+        certfile = mkOption {
+          type = with types; nullOr path;
+          default = null;
+          description = mdDoc "Certificate file for MQTT";
+        };
+        keyfile = mkOption {
+          type = with types; nullOr path;
+          default = null;
+          description = mdDoc "Key file for MQTT";
+        };
+      };
+      influxdb = {
+        host = mkOption {
+          type = types.str;
+          default = "127.0.0.1";
+          description = mdDoc "Host where InfluxDB server is running.";
+        };
+        port = mkOption {
+          type = types.port;
+          default = 8086;
+          description = mdDoc "InfluxDB server port";
+        };
+        database = mkOption {
+          type = types.str;
+          description = mdDoc "Name of the InfluxDB database.";
+        };
+        username = mkOption {
+          type = with types; nullOr str;
+          default = null;
+          description = mdDoc "Username for InfluxDB login.";
+        };
+        password = mkOption {
+          type = with types; nullOr str;
+          default = null;
+          description = mdDoc ''
+            Password for InfluxDB login.
+
+            It is highly suggested to use here replacement through
+            environmentFiles as otherwise the password is put world readable to
+            the store.
+            '';
+        };
+        ssl = mkOption {
+          type = types.bool;
+          default = false;
+          description = mdDoc "Use SSL to connect to the InfluxDB server.";
+        };
+        verify_ssl = mkOption {
+          type = types.bool;
+          default = true;
+          description = mdDoc "Verify SSL certificate when connecting to the InfluxDB server.";
+        };
+      };
+      points = mkOption {
+        type = types.listOf pointType;
+        default = defaultPoints;
+        description = mdDoc "Points to bridge from MQTT to InfluxDB.";
+      };
+    };
+  };
+
+  config = mkIf cfg.enable {
+    systemd.services.bigclown-mqtt2influxdb = let
+      envConfig = cfg.environmentFiles != [];
+      finalConfig = if envConfig
+        then "$RUNTIME_DIRECTORY/mqtt2influxdb.config.yaml"
+        else configFile;
+    in {
+      description = "BigClown MQTT to InfluxDB bridge";
+      wantedBy = ["multi-user.target"];
+      wants = mkIf config.services.mosquitto.enable ["mosquitto.service"];
+      preStart = ''
+        umask 077
+        ${pkgs.envsubst}/bin/envsubst -i "${configFile}" -o "${finalConfig}"
+      '';
+      serviceConfig = {
+        EnvironmentFile = cfg.environmentFiles;
+        ExecStart = "${cfg.package}/bin/mqtt2influxdb -dc ${finalConfig}";
+        RuntimeDirectory = "mqtt2influxdb";
+      };
+    };
+  };
+}