nixos/stubby: reduce to a settings-style configuration

Extract the example configuration from the package to provide a
working example.

Remove pkgs.stubby from `environment.systemPackages`.

3 files changed, 56 insertions, 174 deletions

diff --git a/nixos/doc/manual/from_md/release-notes/rl-2205.section.xml b/nixos/doc/manual/from_md/release-notes/rl-2205.section.xml
index ae6ff9d434ae..d5e3190bf288 100644
--- a/nixos/doc/manual/from_md/release-notes/rl-2205.section.xml
+++ b/nixos/doc/manual/from_md/release-notes/rl-2205.section.xml
@@ -190,6 +190,14 @@
           usage in non-X11 environments, e.g. Wayland.
         </para>
       </listitem>
+      <listitem>
+        <para>
+          The <literal>services.stubby</literal> module was converted to
+          a
+          <link xlink:href="https://github.com/NixOS/rfcs/blob/master/rfcs/0042-config-option.md">settings-style</link>
+          configuration.
+        </para>
+      </listitem>
     </itemizedlist>
   </section>
 </section>
diff --git a/nixos/doc/manual/release-notes/rl-2205.section.md b/nixos/doc/manual/release-notes/rl-2205.section.md
index 3e7f8d451b26..98709455ae74 100644
--- a/nixos/doc/manual/release-notes/rl-2205.section.md
+++ b/nixos/doc/manual/release-notes/rl-2205.section.md
@@ -78,3 +78,5 @@ In addition to numerous new and upgraded packages, this release has the followin
   added, decoupling the setting of `SSH_ASKPASS` from
   `services.xserver.enable`. This allows easy usage in non-X11 environments,
   e.g. Wayland.
+
+- The `services.stubby` module was converted to a [settings-style](https://github.com/NixOS/rfcs/blob/master/rfcs/0042-config-option.md) configuration.
diff --git a/nixos/modules/services/networking/stubby.nix b/nixos/modules/services/networking/stubby.nix
index c5e0f929a126..78c13798dde2 100644
--- a/nixos/modules/services/networking/stubby.nix
+++ b/nixos/modules/services/networking/stubby.nix
@@ -1,180 +1,51 @@
-{ config, lib, pkgs, ...}:
+{ config, lib, pkgs, ... }:
 
 with lib;
 
 let
   cfg = config.services.stubby;
+  settingsFormat = pkgs.formats.yaml { };
+  confFile = settingsFormat.generate "stubby.yml" cfg.settings;
+in {
+  imports = map (x:
+    (mkRemovedOptionModule [ "services" "stubby" x ]
+      "Stubby configuration moved to services.stubby.settings.")) [
+        "authenticationMode"
+        "fallbackProtocols"
+        "idleTimeout"
+        "listenAddresses"
+        "queryPaddingBlocksize"
+        "roundRobinUpstreams"
+        "subnetPrivate"
+        "upstreamServers"
+      ];
 
-  fallbacks = concatMapStringsSep "\n  " (x: "- ${x}") cfg.fallbackProtocols;
-  listeners = concatMapStringsSep "\n  " (x: "- ${x}") cfg.listenAddresses;
-
-  # By default, the recursive resolvers maintained by the getdns
-  # project itself are enabled. More information about both getdns's servers,
-  # as well as third party options for upstream resolvers, can be found here:
-  # https://dnsprivacy.org/wiki/display/DP/DNS+Privacy+Test+Servers
-  #
-  # You can override these values by supplying a yaml-formatted array of your
-  # preferred upstream resolvers in the following format:
-  #
-  # 106 # - address_data: IPv4 or IPv6 address of the upstream
-  #   port: Port for UDP/TCP (default is 53)
-  #   tls_auth_name: Authentication domain name checked against the server
-  #                  certificate
-  #   tls_pubkey_pinset: An SPKI pinset verified against the keys in the server
-  #                      certificate
-  #     - digest: Only "sha256" is currently supported
-  #       value: Base64 encoded value of the sha256 fingerprint of the public
-  #              key
-  #   tls_port: Port for TLS (default is 853)
-
-  defaultUpstream = ''
-    - address_data: 145.100.185.15
-      tls_auth_name: "dnsovertls.sinodun.com"
-      tls_pubkey_pinset:
-        - digest: "sha256"
-          value: 62lKu9HsDVbyiPenApnc4sfmSYTHOVfFgL3pyB+cBL4=
-    - address_data: 145.100.185.16
-      tls_auth_name: "dnsovertls1.sinodun.com"
-      tls_pubkey_pinset:
-        - digest: "sha256"
-          value: cE2ecALeE5B+urJhDrJlVFmf38cJLAvqekONvjvpqUA=
-    - address_data: 185.49.141.37
-      tls_auth_name: "getdnsapi.net"
-      tls_pubkey_pinset:
-        - digest: "sha256"
-          value: foxZRnIh9gZpWnl+zEiKa0EJ2rdCGroMWm02gaxSc9Q=
-    - address_data: 2001:610:1:40ba:145:100:185:15
-      tls_auth_name: "dnsovertls.sinodun.com"
-      tls_pubkey_pinset:
-        - digest: "sha256"
-          value: 62lKu9HsDVbyiPenApnc4sfmSYTHOVfFgL3pyB+cBL4=
-    - address_data: 2001:610:1:40ba:145:100:185:16
-      tls_auth_name: "dnsovertls1.sinodun.com"
-      tls_pubkey_pinset:
-        - digest: "sha256"
-          value: cE2ecALeE5B+urJhDrJlVFmf38cJLAvqekONvjvpqUA=
-    - address_data: 2a04:b900:0:100::38
-      tls_auth_name: "getdnsapi.net"
-      tls_pubkey_pinset:
-        - digest: "sha256"
-          value: foxZRnIh9gZpWnl+zEiKa0EJ2rdCGroMWm02gaxSc9Q=
-  '';
-
-  # Resolution type is not changeable here because it is required per the
-  # stubby documentation:
-  #
-  # "resolution_type: Work in stub mode only (not recursive mode) - required for Stubby
-  # operation."
-  #
-  # https://dnsprivacy.org/wiki/display/DP/Configuring+Stubby
-
-  confFile = pkgs.writeText "stubby.yml" ''
-    resolution_type: GETDNS_RESOLUTION_STUB
-    dns_transport_list:
-      ${fallbacks}
-    appdata_dir: "/var/cache/stubby"
-    tls_authentication: ${cfg.authenticationMode}
-    tls_query_padding_blocksize: ${toString cfg.queryPaddingBlocksize}
-    edns_client_subnet_private: ${if cfg.subnetPrivate then "1" else "0"}
-    idle_timeout: ${toString cfg.idleTimeout}
-    listen_addresses:
-      ${listeners}
-    round_robin_upstreams: ${if cfg.roundRobinUpstreams then "1" else "0"}
-    ${cfg.extraConfig}
-    upstream_recursive_servers:
-    ${cfg.upstreamServers}
-  '';
-in
-
-{
   options = {
     services.stubby = {
 
       enable = mkEnableOption "Stubby DNS resolver";
 
-      fallbackProtocols = mkOption {
-        default = [ "GETDNS_TRANSPORT_TLS" ];
-        type = with types; listOf (enum [
-          "GETDNS_TRANSPORT_TLS"
-          "GETDNS_TRANSPORT_TCP"
-          "GETDNS_TRANSPORT_UDP"
-        ]);
-        description = ''
-          Ordered list composed of one or more transport protocols.
-          Strict mode should only use <literal>GETDNS_TRANSPORT_TLS</literal>.
-          Other options are <literal>GETDNS_TRANSPORT_UDP</literal> and
-          <literal>GETDNS_TRANSPORT_TCP</literal>.
+      settings = mkOption {
+        type = types.attrsOf settingsFormat.type;
+        example = lib.literalExpression ''
+          pkgs.stubby.passthru.settingsExample // {
+            upstream_recursive_servers = [{
+              address_data = "158.64.1.29";
+              tls_auth_name = "kaitain.restena.lu";
+              tls_pubkey_pinset = [{
+                digest = "sha256";
+                value = "7ftvIkA+UeN/ktVkovd/7rPZ6mbkhVI7/8HnFJIiLa4=";
+              }];
+            }];
+          };
         '';
-      };
-
-      authenticationMode = mkOption {
-        default = "GETDNS_AUTHENTICATION_REQUIRED";
-        type = types.enum [
-          "GETDNS_AUTHENTICATION_REQUIRED"
-          "GETDNS_AUTHENTICATION_NONE"
-        ];
         description = ''
-          Selects the Strict or Opportunistic usage profile.
-          For strict, set to <literal>GETDNS_AUTHENTICATION_REQUIRED</literal>.
-          for opportunistic, use <literal>GETDNS_AUTHENTICATION_NONE</literal>.
-        '';
-      };
-
-      queryPaddingBlocksize = mkOption {
-        default = 128;
-        type = types.int;
-        description = ''
-          EDNS0 option to pad the size of the DNS query to the given blocksize.
-        '';
-      };
-
-      subnetPrivate = mkOption {
-        default = true;
-        type = types.bool;
-        description = ''
-          EDNS0 option for ECS client privacy. Default is
-          <literal>true</literal>. If set, this option prevents the client
-          subnet from being sent to authoritative nameservers.
-        '';
-      };
-
-      idleTimeout = mkOption {
-        default = 10000;
-        type = types.int;
-        description = "EDNS0 option for keepalive idle timeout expressed in
-        milliseconds.";
-      };
-
-      listenAddresses = mkOption {
-        default = [ "127.0.0.1" "0::1" ];
-        type = with types; listOf str;
-        description = ''
-          Sets the listen address for the stubby daemon.
-          Uses port 53 by default.
-          Ise IP@port to specify a different port.
-        '';
-      };
-
-      roundRobinUpstreams = mkOption {
-        default = true;
-        type = types.bool;
-        description = ''
-          Instructs stubby to distribute queries across all available name
-          servers. Default is <literal>true</literal>. Set to
-          <literal>false</literal> in order to use the first available.
-        '';
-      };
-
-      upstreamServers = mkOption {
-        default = defaultUpstream;
-        type = types.lines;
-        description = ''
-          Replace default upstreams. See <citerefentry><refentrytitle>stubby
-          </refentrytitle><manvolnum>1</manvolnum></citerefentry> for an
-          example of the entry formatting. In Strict mode, at least one of the
-          following settings must be supplied for each nameserver:
-          <literal>tls_auth_name</literal> or
-          <literal>tls_pubkey_pinset</literal>.
+          Content of the Stubby configuration file. All Stubby settings may be set or queried
+          here. The default settings are available at
+          <literal>pkgs.stubby.passthru.settingsExample</literal>. See
+          <link xlink:href="https://dnsprivacy.org/wiki/display/DP/Configuring+Stubby"/>.
+          A list of the public recursive servers can be found here:
+          <link xlink:href="https://dnsprivacy.org/wiki/display/DP/DNS+Privacy+Test+Servers"/>.
         '';
       };
 
@@ -184,20 +55,21 @@ in
         description = "Enable or disable debug level logging.";
       };
 
-      extraConfig = mkOption {
-        default = "";
-        type = types.lines;
-        description = ''
-          Add additional configuration options. see <citerefentry>
-          <refentrytitle>stubby</refentrytitle><manvolnum>1</manvolnum>
-          </citerefentry>for more options.
-        '';
-      };
     };
   };
 
   config = mkIf cfg.enable {
-    environment.systemPackages = [ pkgs.stubby ];
+    assertions = [{
+      assertion =
+        (cfg.settings.resolution_type or "") == "GETDNS_RESOLUTION_STUB";
+      message = ''
+        services.stubby.settings.resolution_type must be set to "GETDNS_RESOLUTION_STUB".
+        Is services.stubby.settings unset?
+      '';
+    }];
+
+    services.stubby.settings.appdata_dir = "/var/cache/stubby";
+
     systemd.services.stubby = {
       description = "Stubby local DNS resolver";
       after = [ "network.target" ];