move module-based-service parameter types into service

This is in preparation for writing something that extracts them
into documentation.

user configurations now call config.system.service.foo.build { ...params }
instead of config.system.service.foo

the parameter type definitions themselves now move into the
config stanza of the module referencing the service

new helper function  liminix.callService

The only service moved so far is dnsmasq

examples/rotuer.nix

@@ -119,7 +119,7 @@ in rec {
 
   services.dns =
     let interface = services.int;
-    in svc.dnsmasq {
+    in svc.dnsmasq.build {
       resolvconf = services.resolvconf;
       inherit interface;
       ranges = [

modules/dnsmasq/default.nix

@@ -1,14 +1,46 @@
 { lib, pkgs, config, ...}:
 let
   inherit (lib) mkOption types;
+  inherit (pkgs) liminix;
 in {
   options = {
     system.service.dnsmasq = mkOption {
-      type = types.functionTo types.package;
+      type = liminix.lib.types.serviceDefn;
     };
   };
   config = {
-    system.service.dnsmasq = pkgs.callPackage ./service.nix {};
+    system.service.dnsmasq = liminix.callService ./service.nix {
+      user = mkOption {
+        type = types.str;
+        default = "dnsmasq";
+      };
+      group = mkOption {
+        type = types.str;
+        default = "dnsmasq";
+      };
+      resolvconf = mkOption {
+        type = types.nullOr liminix.lib.types.service;
+        default = null;
+      };
+      interface = mkOption {
+        type = liminix.lib.types.service;
+        default = null;
+      };
+      upstreams = mkOption {
+        type = types.listOf types.str;
+        default = [];
+      };
+      ranges = mkOption {
+        type = types.listOf types.str;
+      };
+      domain = mkOption {
+        # this can be given multiple times so probably should be
+        # domains plural and list of string
+        description = "Domain name for DHCP service: causes the DHCP server to return the domain to any hosts which request it, and sets the domain which it is legal for DHCP-configured hosts to claim";
+        type = types.str;
+        example = "example.com";
+      };
+    };
     users.dnsmasq = {
       uid = 51; gid= 51; gecos = "DNS/DHCP service user";
       dir = "/run/dnsmasq";

modules/dnsmasq/service.nix

@@ -4,46 +4,19 @@
 , serviceFns
 , lib
 }:
+{
+  interface
+, user
+, domain
+, group
+, ranges
+, upstreams
+, resolvconf
+}:
 let
+  name = "${interface.device}.dnsmasq";
   inherit (liminix.services) longrun;
   inherit (lib) concatStringsSep;
-  inherit (liminix.lib) typeChecked;
-  inherit (lib) mkOption types;
-
-  t = {
-    user = mkOption {
-      type = types.str;
-      default = "dnsmasq";
-    };
-    group = mkOption {
-      type = types.str;
-      default = "dnsmasq";
-    };
-    resolvconf = mkOption {
-      type = types.nullOr liminix.lib.types.service;
-      default = null;
-    };
-    interface = mkOption {
-      type = liminix.lib.types.service;
-      default = null;
-    };
-    upstreams = mkOption {
-      type = types.listOf types.str;
-      default = [];
-    };
-    ranges = mkOption {
-      type = types.listOf types.str;
-    };
-    domain = mkOption {
-      type = types.str;
-    };
-  };
-in
-params:
-let
-  inherit (typeChecked "dnsmasq" t params)
-    interface user domain group ranges upstreams resolvconf;
-  name = "${interface.device}.dnsmasq";
 in
 longrun {
   inherit name;

pkgs/default.nix

@@ -2,7 +2,14 @@
   callPackage
 , lib
 }:
-{
+let
+  typeChecked = caller: type: value:
+    let
+      inherit (lib) types mergeDefinitions;
+      defs = [{ file = caller; inherit value; }];
+      type' = types.submodule { options = type; };
+    in (mergeDefinitions [] type' defs).mergedValue;
+in {
   pseudofile = callPackage ./pseudofile {};
   liminix = {
     services = callPackage ./liminix-tools/services {};
@@ -11,22 +18,29 @@
       squashfs = callPackage ./liminix-tools/builders/squashfs.nix {};
       kernel = callPackage ./kernel {};
     };
+    callService = path : parameters :
+      let pkg = callPackage path {};
+          checkTypes = t : p : typeChecked (builtins.tostring path) t p;
+      in {
+        inherit parameters;
+        build = args : pkg (checkTypes parameters args);
+      };
     lib = {
-      types = {
-        service =
-          let inherit (lib) types isDerivation hasAttr;
-          in types.package // {
+      types =
+        let inherit (lib) types isDerivation;
+        in  {
+          service = types.package // {
             name = "service";
             description = "s6-rc service";
-            check = x: isDerivation x && hasAttr "serviceType" x;
+            check = x: isDerivation x && x ? serviceType;
+          };
+          serviceDefn = types.attrs // {
+            name = "service-defn";
+            description = "parametrisable s6-rc service definition";
+            check = x: lib.isAttrs x && x ? parameters && x ? build;
           };
         };
-      typeChecked = caller: type: value:
-        let
-          inherit (lib) types mergeDefinitions;
-          defs = [{ file = caller; inherit value; }];
-          type' = types.submodule { options = type; };
-        in (mergeDefinitions [] type' defs).mergedValue;
+      inherit typeChecked;
     };
   };
   writeFennelScript = callPackage ./write-fennel-script {};

tests/pppoe/configuration.nix

@@ -41,7 +41,7 @@ in rec {
     };
 
   services.dns =
-    config.system.service.dnsmasq {
+    config.system.service.dnsmasq.build {
       interface = services.lan4;
       ranges = ["192.168.19.10,192.168.19.253"];
       domain = "fake.liminix.org";