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/postfix.nix

@@ -0,0 +1,98 @@
+{ config, lib, pkgs, options }:
+
+with lib;
+
+let
+  cfg = config.services.prometheus.exporters.postfix;
+in
+{
+  port = 9154;
+  extraOpts = {
+    group = mkOption {
+      type = types.str;
+      description = ''
+        Group under which the postfix exporter shall be run.
+        It should match the group that is allowed to access the
+        <literal>showq</literal> socket in the <literal>queue/public/</literal> directory.
+        Defaults to <literal>services.postfix.setgidGroup</literal> when postfix is enabled.
+      '';
+    };
+    telemetryPath = mkOption {
+      type = types.str;
+      default = "/metrics";
+      description = ''
+        Path under which to expose metrics.
+      '';
+    };
+    logfilePath = mkOption {
+      type = types.path;
+      default = "/var/log/postfix_exporter_input.log";
+      example = "/var/log/mail.log";
+      description = ''
+        Path where Postfix writes log entries.
+        This file will be truncated by this exporter!
+      '';
+    };
+    showqPath = mkOption {
+      type = types.path;
+      default = "/var/lib/postfix/queue/public/showq";
+      example = "/var/spool/postfix/public/showq";
+      description = ''
+        Path where Postfix places its showq socket.
+      '';
+    };
+    systemd = {
+      enable = mkOption {
+        type = types.bool;
+        default = true;
+        description = ''
+          Whether to enable reading metrics from the systemd journal instead of from a logfile
+        '';
+      };
+      unit = mkOption {
+        type = types.str;
+        default = "postfix.service";
+        description = ''
+          Name of the postfix systemd unit.
+        '';
+      };
+      slice = mkOption {
+        type = types.nullOr types.str;
+        default = null;
+        description = ''
+          Name of the postfix systemd slice.
+          This overrides the <option>systemd.unit</option>.
+        '';
+      };
+      journalPath = mkOption {
+        type = types.nullOr types.path;
+        default = null;
+        description = ''
+          Path to the systemd journal.
+        '';
+      };
+    };
+  };
+  serviceOpts = {
+    serviceConfig = {
+      DynamicUser = false;
+      # By default, each prometheus exporter only gets AF_INET & AF_INET6,
+      # but AF_UNIX is needed to read from the `showq`-socket.
+      RestrictAddressFamilies = [ "AF_UNIX" ];
+      ExecStart = ''
+        ${pkgs.prometheus-postfix-exporter}/bin/postfix_exporter \
+          --web.listen-address ${cfg.listenAddress}:${toString cfg.port} \
+          --web.telemetry-path ${cfg.telemetryPath} \
+          --postfix.showq_path ${escapeShellArg cfg.showqPath} \
+          ${concatStringsSep " \\\n  " (cfg.extraFlags
+          ++ optional cfg.systemd.enable "--systemd.enable"
+          ++ optional cfg.systemd.enable (if cfg.systemd.slice != null
+                                          then "--systemd.slice ${cfg.systemd.slice}"
+                                          else "--systemd.unit ${cfg.systemd.unit}")
+          ++ optional (cfg.systemd.enable && (cfg.systemd.journalPath != null))
+                       "--systemd.journal_path ${escapeShellArg cfg.systemd.journalPath}"
+          ++ optional (!cfg.systemd.enable) "--postfix.logfile_path ${escapeShellArg cfg.logfilePath}")}
+      '';
+    };
+  };
+}