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/snmp.nix

@@ -0,0 +1,68 @@
+{ config, lib, pkgs, options }:
+
+with lib;
+
+let
+  cfg = config.services.prometheus.exporters.snmp;
+in
+{
+  port = 9116;
+  extraOpts = {
+    configurationPath = mkOption {
+      type = types.nullOr types.path;
+      default = null;
+      description = ''
+        Path to a snmp exporter configuration file. Mutually exclusive with 'configuration' option.
+      '';
+      example = literalExpression "./snmp.yml";
+    };
+
+    configuration = mkOption {
+      type = types.nullOr types.attrs;
+      default = null;
+      description = ''
+        Snmp exporter configuration as nix attribute set. Mutually exclusive with 'configurationPath' option.
+      '';
+      example = {
+        "default" = {
+          "version" = 2;
+          "auth" = {
+            "community" = "public";
+          };
+        };
+      };
+    };
+
+    logFormat = mkOption {
+      type = types.enum ["logfmt" "json"];
+      default = "logfmt";
+      description = ''
+        Output format of log messages.
+      '';
+    };
+
+    logLevel = mkOption {
+      type = types.enum ["debug" "info" "warn" "error"];
+      default = "info";
+      description = ''
+        Only log messages with the given severity or above.
+      '';
+    };
+  };
+  serviceOpts = let
+    configFile = if cfg.configurationPath != null
+                 then cfg.configurationPath
+                 else "${pkgs.writeText "snmp-exporter-conf.yml" (builtins.toJSON cfg.configuration)}";
+    in {
+    serviceConfig = {
+      ExecStart = ''
+        ${pkgs.prometheus-snmp-exporter}/bin/snmp_exporter \
+          --config.file=${escapeShellArg configFile} \
+          --log.format=${escapeShellArg cfg.logFormat} \
+          --log.level=${cfg.logLevel} \
+          --web.listen-address=${cfg.listenAddress}:${toString cfg.port} \
+          ${concatStringsSep " \\\n  " cfg.extraFlags}
+      '';
+    };
+  };
+}