Flakes/ru: Difference between revisions

Nix flakes обеспечивают единую структуру для Nix-проектов, фиксируют версии зависимостей в лок-файле и делают более удобным написание воспроизводимых Nix-выражений.

* [https://nixos.org/manual/nix/unstable/command-ref/new-cli/nix3-flake.html#description flake]  это файловая структура, корневая директория которой содержит спецификацию Nix в файле <code>flake.nix</code>.

* Содержимое файла <code>flake.nix</code> следует единой схеме наименования для объявления пакетов и их зависимостей на языке Nix.

Флейки вводят [https://nixos.org/manual/nix/stable/command-ref/new-cli/nix3-flake.html#flake-references синтаксис, похожий на URL] для указания удалённых источников.

* Чтобы упростить длинный синтаксис URL с помощью более коротких названий, [https://nixos.org/manual/nix/stable/command-ref/new-cli/nix3-registry.html флейки используют реестр] символических идентификаторов.

* Флейки также позволяют фиксировать ссылки и версии, которые затем могут быть запрошены и обновлены программно.

[https://nixos.org/manual/nix/stable/command-ref/new-cli/nix.html Экспериментальный интерфейс командной строки] принимает ссылки на флейки для выражений, которые создают, запускают и развёртывают пакеты.

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Add the following to the [[Overview_of_the_NixOS_Linux_distribution#Declarative_Configuration system configuration |NixOS configuration]]:

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{{Note | The  [https://github.com/DeterminateSystems/nix-installer Determinate Nix Installer] enables flakes by default.}}

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=== Основное Использование Flake ===

Прежде чем выполнять какие-либо команды nix на этом этапе, обратите внимание на два предупреждения ниже: одно для шифрования, другое для git.

====Encryption WARNING====

{{Warning | Since contents of flake files are copied to the world-readable Nix store folder, do not put any unencrypted secrets in flake files. You should instead use a [[Comparison of secret managing schemes|secret managing scheme]].}}

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==== Предупреждение Git ====

For flakes in git repos, only files in the working tree will be copied to the store.

Therefore, if you use <code>git</code> for your flake, ensure to <code>git add</code> any project files after you first create them.

See also https://www.tweag.io/blog/2020-05-25-flakes/

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====Создание файла flake.nix====

Чтобы начать базовое использование Flakes, выполните команду flake в каталоге проекта:

<syntaxHighlight lang=text>

nix flake init

* <code>nixConfig</code> is an attribute set of values which reflect the [https://nixos.org/manual/nix/stable/command-ref/conf-file.html values given to nix.conf]. This can extend the normal behavior of a user's nix experience by adding flake-specific configuration, such as a binary cache.

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=== Input schema ===

Nixpkgs can be defined using the following code:

== Accessing flakes from Nix expressions ==

If you want to access a flake from within a regular Nix expression on a system that has flakes enabled, you can use something like <code>(builtins.getFlake "/path/to/directory").packages.x86_64-linux.default</code>, where 'directory' is the directory that contains your <code>flake.nix</code>.

Nix flakes run in pure evaluation mode, which is underdocumented. Some tips for now:

* fetchurl and fetchtar [https://github.com/NixOS/nix/blob/36c4d6f59247826dde32ad2e6b5a9471a9a1c911/src/libexpr/primops/fetchTree.cc#L201 require] a sha256 argument to be considered pure.

* builtins.currentSystem is non-hermetic and impure. This can usually be avoided by passing the system (i.e., x86_64-linux) explicitly to derivations requiring it.

outputs = { self, nixpkgs, ... }:

   {

      modules = [

        "${nixpkgs}/nixos/modules/<some-module>.nix"

  };

 

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== Установка пакетов с помощью `nix-profile` ==

 

 

 

{{Ic|nixos-rebuild switch}} will read its configuration from <code>/etc/nixos/flake.nix</code> if it is present.

 

 

  inputs.nixpkgs.url = github:NixOS/nixpkgs/nixos-unstable;

    };

<syntaxhighlight lang="nix">

{

  inputs.nixpkgs.url = github:NixOS/nixpkgs/nixos-unstable;

  inputs.home-manager.url = github:nix-community/home-manager;

 

   outputs = { self, nixpkgs, ... }@inputs: {

     nixosConfigurations.fnord = nixpkgs.lib.nixosSystem {

       specialArgs = { inherit inputs; };

       modules = [ ./configuration.nix ];

     };

To switch a remote host you can use:

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<syntaxhighlight lang="nix">

</syntaxhighlight>

 

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This has the unfortunate side-effect of requiring import-from-derivation and slowing down build times, however it may greatly speed up almost every eval. Full-time flakes users may be able to just use <code>narHash = pkgs.narHash</code>.

 

 

 

 

   inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";

 

   outputs =

    { nixpkgs, ... }:

     {

       /*

        This example assumes your system is x86_64-linux

       devShells.x86_64-linux =

          pkgs = nixpkgs.legacyPackages.x86_64-linux;

        in

        {

          default = pkgs.mkShell {

            packages = [ pkgs.hello ];

And finally, run <code>nix develop</code>. This is what replaces the old nix-shell invocation.

Exit and run again, this command should now be super fast.

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You can easily switch nix shells when you cd into different projects with [https://github.com/nix-community/nix-direnv nix-direnv].

== Pushing Flakes to Cachix ==

== Build specific attributes in a flake repository ==

When in the repository top-level, run <code>nix build .#<attr></code>. It will look in the <code>legacyPackages</code> and <code>packages</code> output attributes for the corresponding derivation.

=== Building flakes from a Git repo url with submodules ===

As per nix 2.9.1, git submodules in package <code>src</code>'s won't get copied to the nix store, this may cause the build to fail.  To workaround this, use:

See: https://github.com/NixOS/nix/pull/5434

When a git folder exists, flake will only copy files added in git to maximize reproducibility (this way if you forgot to add a local file in your repo, you will directly get an error when you try to compile it). However, for development purpose you may want to create an alternative flake file, for instance containing configuration for your preferred editors as described [https://discourse.nixos.org/t/local-personal-development-tools-with-flakes/22714/8 here]… of course without committing this file since it contains only your own preferred tools. You can do so by doing something like that (say for a file called <code>extra/flake.nix</code>):

* [https://nixos.org/manual/nix/unstable/command-ref/new-cli/nix3-flake.html Nix flake command reference manual] - Many additional details about flakes, and their parts.

* [https://www.youtube.com/watch?v=QXUlhnhuRX4&list=PLgknCdxP89RcGPTjngfNR9WmBgvD_xW0l Nix flakes 101: Introduction to nix flakes] (Jörg Thalheim, 2020)

* [https://github.com/NixOS/nix/blob/master/src/nix/flake.md spec describing flake inputs in more detail]

* [https://github.com/numtide/flake-utils flake-utils: Library to avoid some boiler-code when writing flakes]

* [https://zimbatm.com/NixFlakes/#direnv-integration zimbat's direnv article]