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/mail.nix

@@ -0,0 +1,176 @@
+{ config, lib, pkgs, options }:
+
+with lib;
+
+let
+  cfg = config.services.prometheus.exporters.mail;
+
+  configurationFile = pkgs.writeText "prometheus-mail-exporter.conf" (builtins.toJSON (
+    # removes the _module attribute, null values and converts attrNames to lowercase
+    mapAttrs' (name: value:
+      if name == "servers"
+      then nameValuePair (toLower name)
+        ((map (srv: (mapAttrs' (n: v: nameValuePair (toLower n) v)
+          (filterAttrs (n: v: !(n == "_module" || v == null)) srv)
+        ))) value)
+      else nameValuePair (toLower name) value
+    ) (filterAttrs (n: _: !(n == "_module")) cfg.configuration)
+  ));
+
+  serverOptions.options = {
+    name = mkOption {
+      type = types.str;
+      description = ''
+        Value for label 'configname' which will be added to all metrics.
+      '';
+    };
+    server = mkOption {
+      type = types.str;
+      description = ''
+        Hostname of the server that should be probed.
+      '';
+    };
+    port = mkOption {
+      type = types.int;
+      example = 587;
+      description = ''
+        Port to use for SMTP.
+      '';
+    };
+    from = mkOption {
+      type = types.str;
+      example = "exporteruser@domain.tld";
+      description = ''
+        Content of 'From' Header for probing mails.
+      '';
+    };
+    to = mkOption {
+      type = types.str;
+      example = "exporteruser@domain.tld";
+      description = ''
+        Content of 'To' Header for probing mails.
+      '';
+    };
+    detectionDir = mkOption {
+      type = types.path;
+      example = "/var/spool/mail/exporteruser/new";
+      description = ''
+        Directory in which new mails for the exporter user are placed.
+        Note that this needs to exist when the exporter starts.
+      '';
+    };
+    login = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+      example = "exporteruser@domain.tld";
+      description = ''
+        Username to use for SMTP authentication.
+      '';
+    };
+    passphrase = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+      description = ''
+        Password to use for SMTP authentication.
+      '';
+    };
+  };
+
+  exporterOptions.options = {
+    monitoringInterval = mkOption {
+      type = types.str;
+      example = "10s";
+      description = ''
+        Time interval between two probe attempts.
+      '';
+    };
+    mailCheckTimeout = mkOption {
+      type = types.str;
+      description = ''
+        Timeout until mails are considered "didn't make it".
+      '';
+    };
+    disableFileDeletion = mkOption {
+      type = types.bool;
+      default = false;
+      description = ''
+        Disables the exporter's function to delete probing mails.
+      '';
+    };
+    servers = mkOption {
+      type = types.listOf (types.submodule serverOptions);
+      default = [];
+      example = literalExpression ''
+        [ {
+          name = "testserver";
+          server = "smtp.domain.tld";
+          port = 587;
+          from = "exporteruser@domain.tld";
+          to = "exporteruser@domain.tld";
+          detectionDir = "/path/to/Maildir/new";
+        } ]
+      '';
+      description = ''
+        List of servers that should be probed.
+
+        <emphasis>Note:</emphasis> if your mailserver has <citerefentry>
+        <refentrytitle>rspamd</refentrytitle><manvolnum>8</manvolnum></citerefentry> configured,
+        it can happen that emails from this exporter are marked as spam.
+
+        It's possible to work around the issue with a config like this:
+        <programlisting>
+        {
+          <link linkend="opt-services.rspamd.locals._name_.text">services.rspamd.locals."multimap.conf".text</link> = '''
+            ALLOWLIST_PROMETHEUS {
+              filter = "email:domain:tld";
+              type = "from";
+              map = "''${pkgs.writeText "allowmap" "domain.tld"}";
+              score = -100.0;
+            }
+          ''';
+        }
+        </programlisting>
+      '';
+    };
+  };
+in
+{
+  port = 9225;
+  extraOpts = {
+    configFile = mkOption {
+      type = types.nullOr types.path;
+      default = null;
+      description = ''
+        Specify the mailexporter configuration file to use.
+      '';
+    };
+    configuration = mkOption {
+      type = types.nullOr (types.submodule exporterOptions);
+      default = null;
+      description = ''
+        Specify the mailexporter configuration file to use.
+      '';
+    };
+    telemetryPath = mkOption {
+      type = types.str;
+      default = "/metrics";
+      description = ''
+        Path under which to expose metrics.
+      '';
+    };
+  };
+  serviceOpts = {
+    serviceConfig = {
+      DynamicUser = false;
+      ExecStart = ''
+        ${pkgs.prometheus-mail-exporter}/bin/mailexporter \
+          --web.listen-address ${cfg.listenAddress}:${toString cfg.port} \
+          --web.telemetry-path ${cfg.telemetryPath} \
+          --config.file ${
+            if cfg.configuration != null then configurationFile else (escapeShellArg cfg.configFile)
+          } \
+          ${concatStringsSep " \\\n  " cfg.extraFlags}
+      '';
+    };
+  };
+}