fcc95ff817
This allows for correct highlighting and maybe future automatic formatting. The AST was verified to work with nixfmt only.
69 lines
2.7 KiB
Markdown
69 lines
2.7 KiB
Markdown
# Meta Attributes {#sec-meta-attributes}
|
|
|
|
Like Nix packages, NixOS modules can declare meta-attributes to provide
|
|
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`, `doc`, and `buildDocsInSandbox`.
|
|
|
|
Each of the meta-attributes must be defined at most once per module
|
|
file.
|
|
|
|
```nix
|
|
{ config, lib, pkgs, ... }:
|
|
{
|
|
options = {
|
|
# ...
|
|
};
|
|
|
|
config = {
|
|
# ...
|
|
};
|
|
|
|
meta = {
|
|
maintainers = with lib.maintainers; [ ericsagnes ];
|
|
doc = ./default.md;
|
|
buildDocsInSandbox = true;
|
|
};
|
|
}
|
|
```
|
|
|
|
- `maintainers` contains a list of the module maintainers.
|
|
|
|
- `doc` points to a valid [Nixpkgs-flavored CommonMark](
|
|
https://nixos.org/manual/nixpkgs/unstable/#sec-contributing-markup
|
|
) file containing the module
|
|
documentation. Its contents is automatically added to
|
|
[](#ch-configuration). Changes to a module documentation have to
|
|
be checked to not break building the NixOS manual:
|
|
|
|
```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).
|