mirror of
https://github.com/NixOS/nixpkgs.git
synced 2024-11-30 09:31:01 +00:00
85 lines
2.8 KiB
XML
85 lines
2.8 KiB
XML
<chapter xmlns="http://docbook.org/ns/docbook"
|
|
xmlns:xlink="http://www.w3.org/1999/xlink"
|
|
xmlns:xi="http://www.w3.org/2001/XInclude"
|
|
version="5.0"
|
|
xml:id="module-misc-nixos">
|
|
|
|
<title>NixOS Reentry</title>
|
|
|
|
<!-- FIXME: render nicely -->
|
|
|
|
<!-- FIXME: source can be added automatically -->
|
|
<para><emphasis>Source:</emphasis> <filename>modules/misc/nixos.nix</filename></para>
|
|
|
|
<!-- FIXME: more stuff, like maintainer? -->
|
|
|
|
<para>NixOS reentry can be used for both pinning the evaluation to a
|
|
specific version of NixOS, and to dynamically add additional modules into
|
|
the Module evaluation.</para>
|
|
|
|
<section><title>NixOS Version Pinning</title>
|
|
|
|
<para>To pin a specific version of NixOS, you need a version that you can
|
|
either clone localy, or that you can fetch remotely.</para>
|
|
|
|
<para>If you already have a cloned version of NixOS in the directory
|
|
<filename>/etc/nixos/nixpkgs-16-03</filename>, then you can specify the
|
|
<option>nixos.path</option> with either the path or the relative path of
|
|
your NixOS clone. For example, you can add the following to your
|
|
<filename>/etc/nixos/configuration.nix</filename> file:
|
|
|
|
<programlisting>
|
|
nixos.path = ./nixpkgs-16-03/nixos;
|
|
</programlisting>
|
|
</para>
|
|
|
|
<para>Another option is to fetch a specific version of NixOS, with either
|
|
the <literal>fetchTarball</literal> builtin, or the
|
|
<literal>pkgs.fetchFromGitHub</literal> function and use the result as an
|
|
input.
|
|
|
|
<programlisting>
|
|
nixos.path = "${builtins.fetchTarball https://github.com/NixOS/nixpkgs/archive/1f27976e03c15183191d1b4aa1a40d1f14666cd2.tar.gz}/nixos";
|
|
</programlisting>
|
|
</para>
|
|
|
|
</section>
|
|
|
|
|
|
<section><title>Adding Module Dynamically</title>
|
|
|
|
<para>To add additional module, the recommended way is to use statically
|
|
known modules in the list of imported arguments as described in <xref
|
|
linkend="sec-modularity" />. Unfortunately, this recommended method has
|
|
limitation, such that the list of imported files cannot be selected based on
|
|
the content of the configuration.
|
|
|
|
Fortunately, NixOS reentry system can be used as an alternative to register
|
|
new imported modules based on the content of the configuration. To do so,
|
|
one should define both <option>nixos.path</option> and
|
|
<option>nixos.extraModules</option> options.
|
|
|
|
<programlisting>
|
|
nixos.path = <nixos>;
|
|
nixos.extraModules =
|
|
if config.networking.hostName == "server" then
|
|
[ ./server.nix ] else [ ./client.nix ];
|
|
</programlisting>
|
|
|
|
Also note, that the above can be reimplemented in a different way which is
|
|
not as expensive, by using <literal>mkIf</literal> at the top each
|
|
configuration if both modules are present on the file system (see <xref
|
|
linkend="sec-option-definitions" />) and by always inmporting both
|
|
modules.</para>
|
|
|
|
</section>
|
|
|
|
<section><title>Options</title>
|
|
|
|
<para>FIXME: auto-generated list of module options.</para>
|
|
|
|
</section>
|
|
|
|
|
|
</chapter>
|