知っておこう: stdenv

stdenv

stdenv.mkDerivation

誰もが使ったことのある Nixpkgs 収録の関数

builtins.derivation

Nix 言語で一番大事な関数

nuenv (ニューエンヴ)

archive 済み

イケてるシェル

https://scrapbox.io/files/697b3fcbfb63e6bbccf92c9c.png

実装を見る

code:nuenv.nix

{

# The Nuenv build function. Essentially a wrapper around Nix's core derivation function.

mkNushellDerivation =

nushell: # nixpkgs.nushell (from overlay)

sys: # nixpkgs.system (from overlay)

{ name # The name of the derivation

, src # The derivation's sources

, system ? sys # The build system

, build ? "" # The build script itself

, debug ? true # Run in debug mode

, envFile ? ../nuenv/user-env.nu # Nushell environment passed to build phases

, ... # Catch user-supplied env vars

}@attrs:

let

# Gather arbitrary user-supplied environment variables

reservedAttrs = [

"build"

"debug"

"envFile"

"name"

"outputs"

"packages"

"src"

"system"

"__nu_builder"

"__nu_debug"

"__nu_env"

"__nu_extra_attrs"

"__nu_nushell"

];

extraAttrs = removeAttrs attrs reservedAttrs;

in

derivation ({

# Core derivation info

inherit envFile name outputs packages src system;

# Realisation phases (just one for now)

inherit build;

# Build logic

builder = "${nushell}/bin/nu"; # Use Nushell instead of Bash

# When this is set, Nix writes the environment to a JSON file at

# $NIX_BUILD_TOP/.attrs.json. Because Nushell can handle JSON natively, this approach

# is generally cleaner than parsing environment variables as strings.

__structuredAttrs = true;

# Attributes passed to the environment (prefaced with __nu_ to avoid naming collisions)

__nu_builder = ../nuenv/builder.nu;

__nu_debug = debug;

__nu_extra_attrs = extraAttrs;

__nu_nushell = "${nushell}/bin/nu";

} // extraAttrs);

# An analogue to writeScriptBin but for Nushell rather than Bash scripts.

mkNushellScript =

nushell: # nixpkgs.nushell (from overlay)

writeTextFile: # Utility function (from overlay)

{ name

, script

, bin ? name

}:

let

nu = "${nushell}/bin/nu";

in

writeTextFile {

inherit name;

destination = "/bin/${bin}";

text = ''

${script}

'';

executable = true;

};

}

これだけ？

たった85行

「Nix 言語側」で行っていることは少ない

大部分はシェルスクリプトで実行される

実はめっちゃプリミティブ: derivation 関数

特別扱いされる attribute

etc...

A. 環境変数

stdenv がやっていること: 色んなものを環境変数にぶち込んでシェルスクリプトでガチャガチャする

nuenv の builder

code:nuenv.nix

builder = "${nushell}/bin/nu"; # Use Nushell instead of Bash

bootstrap.nu

1. nushell 定義のヘルパー関数の導入

2. PATH に nuenv 関連の実行可能ファイル追加

code:bootstrap.nu

# This script performs any necessary setup before the builder.nu script is run.

# Discover and load the .attrs.json file, which supplies Nuenv with all the

# information it needs to realise the derivation.

let here = $env.NIX_BUILD_TOP

let attrsJsonFile = if ($env.NIX_ATTRS_JSON_FILE | path exists) {

$env.NIX_ATTRS_JSON_FILE

} else {

$"($here)/.attrs.json"

}

let attrs = (open $attrsJsonFile)

# Copy all .nu helper files into the sandbox

for file in $attrs.__nu_env {

let filename = ($file | parse "{__root}-{filename}" | get filename.0)

let target = $"($here)/($filename)"

cp $file $target

}

# Set the PATH so that Nushell itself is discoverable. The PATH will be

# overwritten later.

$env.PATH = ($attrs.__nu_nushell | parse "{root}/nu" | get root.0)

# Run the Nushell builder

nu --commands (open $attrs.__nu_builder)

builder.nu

code:builder.nu

# Copy sources into sandbox

if $nix.debug { info "Copying sources" }

for src in $drv.src { cp -r -f $src $nix.sandbox }

code:builder.nu

let packagesPath = (

$drv.packages # List of strings

| each { |pkg| $"($pkg)/bin" } # Append /bin to each package path

| str join (char esep) # Collect into a single colon-separated string

)

$env.PATH = $packagesPath

フェーズ

mkDerivation の再利用性を高めるためにビルドに関わるステップを分割している

など

stdenv と C/C++

stdenv は C/C++ プロジェクトを自動でビルドするために最適化されている

フェーズの初期値

C 言語のパッケージビルド向けに調整されている

例えばGNU 製のパッケージの場合、名前・バージョン・ソースコードさえ指定すれば、あとは追加でほぼ何も書かずにビルド可能

nuenv でやっていないこと

共有ライブラリをいい感じにする

バイナリファイルに共有ライブラリのストアパスを埋め込む

bootstrap