Merge pull request #149532 from pennae/split-docs-build

nixos/*: split docs build

3 files changed, 82 insertions, 7 deletions

diff --git a/nixos/doc/manual/default.nix b/nixos/doc/manual/default.nix
index 31b6da01c6b..52d500c64d3 100644
--- a/nixos/doc/manual/default.nix
+++ b/nixos/doc/manual/default.nix
@@ -1,4 +1,13 @@
-{ pkgs, options, config, version, revision, extraSources ? [] }:
+{ pkgs
+, options
+, config
+, version
+, revision
+, extraSources ? []
+, baseOptionsJSON ? null
+, warningsAreErrors ? true
+, prefix ? ../../..
+}:
 
 with pkgs;
 
@@ -11,11 +20,11 @@ let
   #
   # E.g. if some `options` came from modules in ${pkgs.customModules}/nix,
   # you'd need to include `extraSources = [ pkgs.customModules ]`
-  prefixesToStrip = map (p: "${toString p}/") ([ ../../.. ] ++ extraSources);
+  prefixesToStrip = map (p: "${toString p}/") ([ prefix ] ++ extraSources);
   stripAnyPrefixes = lib.flip (lib.foldr lib.removePrefix) prefixesToStrip;
 
   optionsDoc = buildPackages.nixosOptionsDoc {
-    inherit options revision;
+    inherit options revision baseOptionsJSON warningsAreErrors;
     transformOptions = opt: opt // {
       # Clean up declaration sites to not refer to the NixOS source tree.
       declarations = map stripAnyPrefixes opt.declarations;
@@ -161,7 +170,7 @@ let
 in rec {
   inherit generatedSources;
 
-  inherit (optionsDoc) optionsJSON optionsDocBook;
+  inherit (optionsDoc) optionsJSON optionsNix optionsDocBook;
 
   # Generate the NixOS manual.
   manualHTML = runCommand "nixos-manual-html"
diff --git a/nixos/doc/manual/development/meta-attributes.section.md b/nixos/doc/manual/development/meta-attributes.section.md
index ca4ba007f7d..946c08efd0a 100644
--- a/nixos/doc/manual/development/meta-attributes.section.md
+++ b/nixos/doc/manual/development/meta-attributes.section.md
@@ -5,7 +5,7 @@ extra information. Module meta attributes are defined in the `meta.nix`
 special module.
 
 `meta` is a top level attribute like `options` and `config`. Available
-meta-attributes are `maintainers` and `doc`.
+meta-attributes are `maintainers`, `doc`, and `buildDocsInSandbox`.
 
 Each of the meta-attributes must be defined at most once per module
 file.
@@ -24,6 +24,7 @@ file.
   meta = {
     maintainers = with lib.maintainers; [ ericsagnes ];
     doc = ./default.xml;
+    buildDocsInSandbox = true;
   };
 }
 ```
@@ -38,3 +39,28 @@ file.
     ```ShellSession
     $ nix-build nixos/release.nix -A manual.x86_64-linux
     ```
+
+-  `buildDocsInSandbox` indicates whether the option documentation for the
+   module can be built in a derivation sandbox. This option is currently only
+   honored for modules shipped by nixpkgs. User modules and modules taken from
+   `NIXOS_EXTRA_MODULE_PATH` are always built outside of the sandbox, as has
+   been the case in previous releases.
+
+   Building NixOS option documentation in a sandbox allows caching of the built
+   documentation, which greatly decreases the amount of time needed to evaluate
+   a system configuration that has NixOS documentation enabled. The sandbox also
+   restricts which attributes may be referenced by documentation attributes
+   (such as option descriptions) to the `options` and `lib` module arguments and
+   the `pkgs.formats` attribute of the `pkgs` argument, `config` and the rest of
+   `pkgs` are disallowed and will cause doc build failures when used. This
+   restriction is necessary because we cannot reproduce the full nixpkgs
+   instantiation with configuration and overlays from a system configuration
+   inside the sandbox. The `options` argument only includes options of modules
+   that are also built inside the sandbox, referencing an option of a module
+   that isn't built in the sandbox is also forbidden.
+
+   The default is `true` and should usually not be changed; set it to `false`
+   only if the module requires access to `pkgs` in its documentation (e.g.
+   because it loads information from a linked package to build an option type)
+   or if its documentation depends on other modules that also aren't sandboxed
+   (e.g. by using types defined in the other module).
diff --git a/nixos/doc/manual/from_md/development/meta-attributes.section.xml b/nixos/doc/manual/from_md/development/meta-attributes.section.xml
index f535d94602b..1eb6e0f3036 100644
--- a/nixos/doc/manual/from_md/development/meta-attributes.section.xml
+++ b/nixos/doc/manual/from_md/development/meta-attributes.section.xml
@@ -8,8 +8,8 @@
   <para>
     <literal>meta</literal> is a top level attribute like
     <literal>options</literal> and <literal>config</literal>. Available
-    meta-attributes are <literal>maintainers</literal> and
-    <literal>doc</literal>.
+    meta-attributes are <literal>maintainers</literal>,
+    <literal>doc</literal>, and <literal>buildDocsInSandbox</literal>.
   </para>
   <para>
     Each of the meta-attributes must be defined at most once per module
@@ -29,6 +29,7 @@
   meta = {
     maintainers = with lib.maintainers; [ ericsagnes ];
     doc = ./default.xml;
+    buildDocsInSandbox = true;
   };
 }
 </programlisting>
@@ -51,5 +52,44 @@
 $ nix-build nixos/release.nix -A manual.x86_64-linux
 </programlisting>
     </listitem>
+    <listitem>
+      <para>
+        <literal>buildDocsInSandbox</literal> indicates whether the
+        option documentation for the module can be built in a derivation
+        sandbox. This option is currently only honored for modules
+        shipped by nixpkgs. User modules and modules taken from
+        <literal>NIXOS_EXTRA_MODULE_PATH</literal> are always built
+        outside of the sandbox, as has been the case in previous
+        releases.
+      </para>
+      <para>
+        Building NixOS option documentation in a sandbox allows caching
+        of the built documentation, which greatly decreases the amount
+        of time needed to evaluate a system configuration that has NixOS
+        documentation enabled. The sandbox also restricts which
+        attributes may be referenced by documentation attributes (such
+        as option descriptions) to the <literal>options</literal> and
+        <literal>lib</literal> module arguments and the
+        <literal>pkgs.formats</literal> attribute of the
+        <literal>pkgs</literal> argument, <literal>config</literal> and
+        the rest of <literal>pkgs</literal> are disallowed and will
+        cause doc build failures when used. This restriction is
+        necessary because we cannot reproduce the full nixpkgs
+        instantiation with configuration and overlays from a system
+        configuration inside the sandbox. The <literal>options</literal>
+        argument only includes options of modules that are also built
+        inside the sandbox, referencing an option of a module that isn’t
+        built in the sandbox is also forbidden.
+      </para>
+      <para>
+        The default is <literal>true</literal> and should usually not be
+        changed; set it to <literal>false</literal> only if the module
+        requires access to <literal>pkgs</literal> in its documentation
+        (e.g. because it loads information from a linked package to
+        build an option type) or if its documentation depends on other
+        modules that also aren’t sandboxed (e.g. by using types defined
+        in the other module).
+      </para>
+    </listitem>
   </itemizedlist>
 </section>