uboot: (firmwareOdroidC2/C4) don't invoke patch tool, use patches = [] instead

https://github.com/NixOS/nixpkgs/blob/master/pkgs/stdenv/generic/setup.sh#L948
this can do it nicely.

Signed-off-by: Anton Arapov <anton@deadbeef.mx>

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

@@ -0,0 +1,50 @@
+{ config, lib, pkgs, options }:
+
+with lib;
+
+let
+  cfg = config.services.prometheus.exporters.flow;
+in {
+  port = 9590;
+  extraOpts = {
+    brokers = mkOption {
+      type = types.listOf types.str;
+      example = literalExpression ''[ "kafka.example.org:19092" ]'';
+      description = "List of Kafka brokers to connect to.";
+    };
+
+    asn = mkOption {
+      type = types.ints.positive;
+      example = 65542;
+      description = "The ASN being monitored.";
+    };
+
+    partitions = mkOption {
+      type = types.listOf types.int;
+      default = [];
+      description = ''
+        The number of the partitions to consume, none means all.
+      '';
+    };
+
+    topic = mkOption {
+      type = types.str;
+      example = "pmacct.acct";
+      description = "The Kafka topic to consume from.";
+    };
+  };
+
+  serviceOpts = {
+    serviceConfig = {
+      DynamicUser = true;
+      ExecStart = ''
+        ${pkgs.prometheus-flow-exporter}/bin/flow-exporter \
+          -asn ${toString cfg.asn} \
+          -topic ${cfg.topic} \
+          -brokers ${concatStringsSep "," cfg.brokers} \
+          ${optionalString (cfg.partitions != []) "-partitions ${concatStringsSep "," cfg.partitions}"} \
+          -addr ${cfg.listenAddress}:${toString cfg.port} ${concatStringsSep " " cfg.extraFlags}
+      '';
+    };
+  };
+}