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author | Nicolas B. Pierron <nicolas.b.pierron@gmail.com> | 2015-11-20 20:11:21 +0000 |
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committer | Nicolas B. Pierron <nicolas.b.pierron@gmail.com> | 2015-11-20 20:11:21 +0000 |
commit | 4e61fc89d261eb4815186b451e43a5925a4eb2a1 (patch) | |
tree | 18a0003e7d917216a91d5f1e544c5f11f029b4de /nixos/modules/misc | |
parent | eae62caf916bae65c40a69f88a088d540c6c7765 (diff) | |
parent | a5992ad61b314104aff7e28a41ce101a1b0e7c35 (diff) | |
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Merge pull request #11106 from nbp/nixos-reentry
Add a way to pin a NixOS version within the module system.
Diffstat (limited to 'nixos/modules/misc')
-rw-r--r-- | nixos/modules/misc/nixos.nix | 82 | ||||
-rw-r--r-- | nixos/modules/misc/nixos.xml | 84 |
2 files changed, 166 insertions, 0 deletions
diff --git a/nixos/modules/misc/nixos.nix b/nixos/modules/misc/nixos.nix new file mode 100644 index 000000000000..356129211d06 --- /dev/null +++ b/nixos/modules/misc/nixos.nix @@ -0,0 +1,82 @@ +{ config, options, lib, ... }: + +# This modules is used to inject a different NixOS version as well as its +# argument such that one can pin a specific version with the versionning +# system of the configuration. +let + nixosReentry = import config.nixos.path { + inherit (config.nixos) configuration extraModules; + inherit (config.nixpkgs) system; + reEnter = true; + }; +in + +with lib; + +{ + options = { + nixos.path = mkOption { + default = null; + example = literalExample "./nixpkgs-15.09/nixos"; + type = types.nullOr types.path; + description = '' + This option give the ability to evaluate the current set of modules + with a different version of NixOS. This option can be used version + the version of NixOS with the configuration without relying on the + <literal>NIX_PATH</literal> environment variable. + ''; + }; + + nixos.system = mkOption { + example = "i686-linux"; + type = types.uniq types.str; + description = '' + Name of the system used to compile NixOS. + ''; + }; + + nixos.extraModules = mkOption { + default = []; + example = literalExample "mkIf config.services.openssh.enable [ ./sshd-config.nix ]"; + type = types.listOf types.unspecified; + description = '' + Define additional modules which would be loaded to evaluate the + configuration. + ''; + }; + + nixos.configuration = mkOption { + type = types.unspecified; + internal = true; + description = '' + Option used by <filename>nixos/default.nix</filename> to re-inject + the same configuration module as the one used for the current + execution. + ''; + }; + + nixos.reflect = mkOption { + default = { inherit config options; }; + type = types.unspecified; + internal = true; + description = '' + Provides <literal>config</literal> and <literal>options</literal> + computed by the module system and given as argument to all + modules. These are used for introspection of options and + configuration by tools such as <literal>nixos-option</literal>. + ''; + }; + }; + + config = mkMerge [ + (mkIf (config.nixos.path != null) (mkForce { + system.build.toplevel = nixosReentry.system; + system.build.vm = nixosReentry.vm; + nixos.reflect = { inherit (nixosReentry) config options; }; + })) + + { meta.maintainers = singleton lib.maintainers.pierron; + meta.doc = ./nixos.xml; + } + ]; +} diff --git a/nixos/modules/misc/nixos.xml b/nixos/modules/misc/nixos.xml new file mode 100644 index 000000000000..f8d3b4bc6e33 --- /dev/null +++ b/nixos/modules/misc/nixos.xml @@ -0,0 +1,84 @@ +<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> |