Extract NixOS options documentation generation to a function

Motivation is to support other repositories containing nixos
modules that would like to generate options documentation:

- nix-darwin
- private repos
- arion
- ??

5 files changed, 138 insertions, 97 deletions

diff --git a/nixos/doc/manual/default.nix b/nixos/doc/manual/default.nix
index 7fc0ad702f8..f9de2db1a08 100644
--- a/nixos/doc/manual/default.nix
+++ b/nixos/doc/manual/default.nix
@@ -5,55 +5,6 @@ with pkgs;
 let
   lib = pkgs.lib;
 
-  # Remove invisible and internal options.
-  optionsListVisible = lib.filter (opt: opt.visible && !opt.internal) (lib.optionAttrSetToDocList options);
-
-  # Replace functions by the string <function>
-  substFunction = x:
-    if builtins.isAttrs x then lib.mapAttrs (name: substFunction) x
-    else if builtins.isList x then map substFunction x
-    else if lib.isFunction x then "<function>"
-    else x;
-
-  # Generate DocBook documentation for a list of packages. This is
-  # what `relatedPackages` option of `mkOption` from
-  # ../../../lib/options.nix influences.
-  #
-  # Each element of `relatedPackages` can be either
-  # - a string:  that will be interpreted as an attribute name from `pkgs`,
-  # - a list:    that will be interpreted as an attribute path from `pkgs`,
-  # - an attrset: that can specify `name`, `path`, `package`, `comment`
-  #   (either of `name`, `path` is required, the rest are optional).
-  genRelatedPackages = packages:
-    let
-      unpack = p: if lib.isString p then { name = p; }
-                  else if lib.isList p then { path = p; }
-                  else p;
-      describe = args:
-        let
-          title = args.title or null;
-          name = args.name or (lib.concatStringsSep "." args.path);
-          path = args.path or [ args.name ];
-          package = args.package or (lib.attrByPath path (throw "Invalid package attribute path `${toString path}'") pkgs);
-        in "<listitem>"
-        + "<para><literal>${lib.optionalString (title != null) "${title} aka "}pkgs.${name} (${package.meta.name})</literal>"
-        + lib.optionalString (!package.meta.available) " <emphasis>[UNAVAILABLE]</emphasis>"
-        + ": ${package.meta.description or "???"}.</para>"
-        + lib.optionalString (args ? comment) "\n<para>${args.comment}</para>"
-        # Lots of `longDescription's break DocBook, so we just wrap them into <programlisting>
-        + lib.optionalString (package.meta ? longDescription) "\n<programlisting>${package.meta.longDescription}</programlisting>"
-        + "</listitem>";
-    in "<itemizedlist>${lib.concatStringsSep "\n" (map (p: describe (unpack p)) packages)}</itemizedlist>";
-
-  optionsListDesc = lib.flip map optionsListVisible (opt: opt // {
-    # Clean up declaration sites to not refer to the NixOS source tree.
-    declarations = map stripAnyPrefixes opt.declarations;
-  }
-  // lib.optionalAttrs (opt ? example) { example = substFunction opt.example; }
-  // lib.optionalAttrs (opt ? default) { default = substFunction opt.default; }
-  // lib.optionalAttrs (opt ? type) { type = substFunction opt.type; }
-  // lib.optionalAttrs (opt ? relatedPackages && opt.relatedPackages != []) { relatedPackages = genRelatedPackages opt.relatedPackages; });
-
   # We need to strip references to /nix/store/* from options,
   # including any `extraSources` if some modules came from elsewhere,
   # or else the build will fail.
@@ -63,37 +14,13 @@ let
   prefixesToStrip = map (p: "${toString p}/") ([ ../../.. ] ++ extraSources);
   stripAnyPrefixes = lib.flip (lib.fold lib.removePrefix) prefixesToStrip;
 
-  # Custom "less" that pushes up all the things ending in ".enable*"
-  # and ".package*"
-  optionLess = a: b:
-    let
-      ise = lib.hasPrefix "enable";
-      isp = lib.hasPrefix "package";
-      cmp = lib.splitByAndCompare ise lib.compare
-                                 (lib.splitByAndCompare isp lib.compare lib.compare);
-    in lib.compareLists cmp a.loc b.loc < 0;
-
-  # Customly sort option list for the man page.
-  optionsList = lib.sort optionLess optionsListDesc;
-
-  # Convert the list of options into an XML file.
-  optionsXML = builtins.toFile "options.xml" (builtins.toXML optionsList);
-
-  optionsDocBook = runCommand "options-db.xml" {} ''
-    optionsXML=${optionsXML}
-    if grep /nixpkgs/nixos/modules $optionsXML; then
-      echo "The manual appears to depend on the location of Nixpkgs, which is bad"
-      echo "since this prevents sharing via the NixOS channel.  This is typically"
-      echo "caused by an option default that refers to a relative path (see above"
-      echo "for hints about the offending path)."
-      exit 1
-    fi
-    ${buildPackages.libxslt.bin}/bin/xsltproc \
-      --stringparam revision '${revision}' \
-      -o intermediate.xml ${./options-to-docbook.xsl} $optionsXML
-    ${buildPackages.libxslt.bin}/bin/xsltproc \
-      -o "$out" ${./postprocess-option-descriptions.xsl} intermediate.xml
-  '';
+  optionsDoc = buildPackages.nixosOptionsDoc {
+    inherit options revision;
+    transformOptions = opt: opt // {
+      # Clean up declaration sites to not refer to the NixOS source tree.
+      declarations = map stripAnyPrefixes opt.declarations;
+    };
+  };
 
   sources = lib.sourceFilesBySuffices ./. [".xml"];
 
@@ -108,7 +35,7 @@ let
   generatedSources = runCommand "generated-docbook" {} ''
     mkdir $out
     ln -s ${modulesDoc} $out/modules.xml
-    ln -s ${optionsDocBook} $out/options-db.xml
+    ln -s ${optionsDoc.optionsDocBook} $out/options-db.xml
     printf "%s" "${version}" > $out/version
   '';
 
@@ -234,22 +161,7 @@ let
 in rec {
   inherit generatedSources;
 
-  # The NixOS options in JSON format.
-  optionsJSON = runCommand "options-json"
-    { meta.description = "List of NixOS options in JSON format";
-    }
-    ''
-      # Export list of options in different format.
-      dst=$out/share/doc/nixos
-      mkdir -p $dst
-
-      cp ${builtins.toFile "options.json" (builtins.unsafeDiscardStringContext (builtins.toJSON
-        (builtins.listToAttrs (map (o: { name = o.name; value = removeAttrs o ["name" "visible" "internal"]; }) optionsList))))
-      } $dst/options.json
-
-      mkdir -p $out/nix-support
-      echo "file json $dst/options.json" >> $out/nix-support/hydra-build-products
-    ''; # */
+  inherit (optionsDoc) optionsJSON optionsXML optionsDocBook;
 
   # Generate the NixOS manual.
   manualHTML = runCommand "nixos-manual-html"
diff --git a/nixos/lib/make-options-doc/default.nix b/nixos/lib/make-options-doc/default.nix
new file mode 100644
index 00000000000..c22c7500335
--- /dev/null
+++ b/nixos/lib/make-options-doc/default.nix
@@ -0,0 +1,125 @@
+/* Generate JSON, XML and DocBook documentation for given NixOS options.
+
+   Minimal example:
+
+    { pkgs,  }:
+
+    let
+      eval = import (pkgs.path + "/nixos/lib/eval-config.nix") {
+        baseModules = [
+          ../module.nix
+        ];
+        modules = [];
+      };
+    in pkgs.nixosOptionsDoc {
+      options = eval.options;
+    }
+
+*/
+{ pkgs
+, lib
+, options
+, transformOptions ? lib.id  # function for additional tranformations of the options
+, revision ? "" # Specify revision for the options
+}:
+
+let
+  # Replace functions by the string <function>
+  substFunction = x:
+    if builtins.isAttrs x then lib.mapAttrs (name: substFunction) x
+    else if builtins.isList x then map substFunction x
+    else if lib.isFunction x then "<function>"
+    else x;
+
+  optionsListDesc = lib.flip map optionsListVisible
+   (opt: transformOptions opt
+    // lib.optionalAttrs (opt ? example) { example = substFunction opt.example; }
+    // lib.optionalAttrs (opt ? default) { default = substFunction opt.default; }
+    // lib.optionalAttrs (opt ? type) { type = substFunction opt.type; }
+    // lib.optionalAttrs (opt ? relatedPackages && opt.relatedPackages != []) { relatedPackages = genRelatedPackages opt.relatedPackages; }
+   );
+
+  # Generate DocBook documentation for a list of packages. This is
+  # what `relatedPackages` option of `mkOption` from
+  # ../../../lib/options.nix influences.
+  #
+  # Each element of `relatedPackages` can be either
+  # - a string:  that will be interpreted as an attribute name from `pkgs`,
+  # - a list:    that will be interpreted as an attribute path from `pkgs`,
+  # - an attrset: that can specify `name`, `path`, `package`, `comment`
+  #   (either of `name`, `path` is required, the rest are optional).
+  genRelatedPackages = packages:
+    let
+      unpack = p: if lib.isString p then { name = p; }
+                  else if lib.isList p then { path = p; }
+                  else p;
+      describe = args:
+        let
+          title = args.title or null;
+          name = args.name or (lib.concatStringsSep "." args.path);
+          path = args.path or [ args.name ];
+          package = args.package or (lib.attrByPath path (throw "Invalid package attribute path `${toString path}'") pkgs);
+        in "<listitem>"
+        + "<para><literal>${lib.optionalString (title != null) "${title} aka "}pkgs.${name} (${package.meta.name})</literal>"
+        + lib.optionalString (!package.meta.available) " <emphasis>[UNAVAILABLE]</emphasis>"
+        + ": ${package.meta.description or "???"}.</para>"
+        + lib.optionalString (args ? comment) "\n<para>${args.comment}</para>"
+        # Lots of `longDescription's break DocBook, so we just wrap them into <programlisting>
+        + lib.optionalString (package.meta ? longDescription) "\n<programlisting>${package.meta.longDescription}</programlisting>"
+        + "</listitem>";
+    in "<itemizedlist>${lib.concatStringsSep "\n" (map (p: describe (unpack p)) packages)}</itemizedlist>";
+
+  # Custom "less" that pushes up all the things ending in ".enable*"
+  # and ".package*"
+  optionLess = a: b:
+    let
+      ise = lib.hasPrefix "enable";
+      isp = lib.hasPrefix "package";
+      cmp = lib.splitByAndCompare ise lib.compare
+                                 (lib.splitByAndCompare isp lib.compare lib.compare);
+    in lib.compareLists cmp a.loc b.loc < 0;
+
+  # Remove invisible and internal options.
+  optionsListVisible = lib.filter (opt: opt.visible && !opt.internal) (lib.optionAttrSetToDocList options);
+
+  # Customly sort option list for the man page.
+  optionsList = lib.sort optionLess optionsListDesc;
+
+  # Convert the list of options into an XML file.
+  optionsXML = builtins.toFile "options.xml" (builtins.toXML optionsList);
+
+in rec {
+  # The NixOS options in JSON format.
+  optionsJSON = pkgs.runCommand "options.json"
+    { meta.description = "List of NixOS options in JSON format";
+    }
+    ''
+      # Export list of options in different format.
+      dst=$out/share/doc/nixos
+      mkdir -p $dst
+
+      cp ${builtins.toFile "options.json" (builtins.unsafeDiscardStringContext (builtins.toJSON
+        (builtins.listToAttrs (map (o: { name = o.name; value = removeAttrs o ["name" "visible" "internal"]; }) optionsList))))
+      } $dst/options.json
+
+      mkdir -p $out/nix-support
+      echo "file json $dst/options.json" >> $out/nix-support/hydra-build-products
+    ''; # */
+
+  optionsDocBook = pkgs.runCommand "options-docbook.xml" {} ''
+    optionsXML=${optionsXML}
+    if grep /nixpkgs/nixos/modules $optionsXML; then
+      echo "The manual appears to depend on the location of Nixpkgs, which is bad"
+      echo "since this prevents sharing via the NixOS channel.  This is typically"
+      echo "caused by an option default that refers to a relative path (see above"
+      echo "for hints about the offending path)."
+      exit 1
+    fi
+
+    ${pkgs.libxslt.bin}/bin/xsltproc \
+      --stringparam revision '${revision}' \
+      -o intermediate.xml ${./options-to-docbook.xsl} $optionsXML
+    ${pkgs.libxslt.bin}/bin/xsltproc \
+      -o "$out" ${./postprocess-option-descriptions.xsl} intermediate.xml
+  '';
+}
diff --git a/nixos/doc/manual/options-to-docbook.xsl b/nixos/lib/make-options-doc/options-to-docbook.xsl
index 72ac89d4ff6..72ac89d4ff6 100644
--- a/nixos/doc/manual/options-to-docbook.xsl
+++ b/nixos/lib/make-options-doc/options-to-docbook.xsl
diff --git a/nixos/doc/manual/postprocess-option-descriptions.xsl b/nixos/lib/make-options-doc/postprocess-option-descriptions.xsl
index 1201c7612c2..1201c7612c2 100644
--- a/nixos/doc/manual/postprocess-option-descriptions.xsl
+++ b/nixos/lib/make-options-doc/postprocess-option-descriptions.xsl
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index a4c800839e3..d6cc9b846bd 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -23876,6 +23876,10 @@ in
         in
           nixosTesting.makeTest calledTest;
 
+  nixosOptionsDoc = attrs: 
+    (import ../../nixos/lib/make-options-doc/default.nix)
+    ({ inherit pkgs lib; } // attrs);
+
   nixui = callPackage ../tools/package-management/nixui { node_webkit = nwjs_0_12; };
 
   nixdoc = callPackage ../tools/nix/nixdoc {};