mirror of
https://github.com/ryan4yin/nixos-and-flakes-book
synced 2024-12-25 03:43:11 +00:00
294 lines
11 KiB
Markdown
294 lines
11 KiB
Markdown
# 在 NixOS 上进行开发工作
|
||
|
||
由于 NixOS 自身可复现的特性，它非常适合用于搭建开发环境。
|
||
但是如果你想直接将在其他发行版上的环境搭建经验用在 NixOS 上，可能会遇到许多问题，因为 NixOS 有自己的一套逻辑在，下面我们先对此稍作说明。
|
||
|
||
在 NixOS 上，全局环境中只建议安装一些通用的工具，比如 `git`、`vim`、`emacs`、`tmux`、`zsh` 等等，而各语言的开发环境，最好是每个项目都有一个独立的环境。
|
||
为了简便，你也可以考虑提前为常用语言创建一些通用的开发环境，在需要时切换进去。
|
||
|
||
总而言之，NixOS 上的开发环境不应该装在全局，应该是一个个独立的项目环境，或许还带有一些通用的语言环境，但是它们都是完全隔离的，不会相互影响。
|
||
|
||
在本章中我们先学习一下 Nix Flakes 开发环境的实现原理，后面的章节再按使用场景介绍一些更具体的内容。
|
||
|
||
## 创建与使用开发环境
|
||
|
||
在 Nix Flakes 中，我们可以通过 `pkgs.mkShell { ... }` 来定义一个项目环境，通过 `nix develop` 来打开一个该开发环境的交互式 Bash Shell.
|
||
|
||
为了更好的使用上述两个功能，我们先来看看它们的原理。
|
||
|
||
[`pkgs.mkShell` 的源码](https://github.com/NixOS/nixpkgs/blob/master/pkgs/build-support/mkshell/default.nix)如下：
|
||
|
||
```nix
|
||
{ lib, stdenv, buildEnv }:
|
||
|
||
# A special kind of derivation that is only meant to be consumed by the
|
||
# nix-shell.
|
||
{ name ? "nix-shell"
|
||
, # a list of packages to add to the shell environment
|
||
packages ? [ ]
|
||
, # propagate all the inputs from the given derivations
|
||
inputsFrom ? [ ]
|
||
, buildInputs ? [ ]
|
||
, nativeBuildInputs ? [ ]
|
||
, propagatedBuildInputs ? [ ]
|
||
, propagatedNativeBuildInputs ? [ ]
|
||
, ...
|
||
}@attrs:
|
||
let
|
||
mergeInputs = name:
|
||
(attrs.${name} or [ ]) ++
|
||
(lib.subtractLists inputsFrom (lib.flatten (lib.catAttrs name inputsFrom)));
|
||
|
||
rest = builtins.removeAttrs attrs [
|
||
"name"
|
||
"packages"
|
||
"inputsFrom"
|
||
"buildInputs"
|
||
"nativeBuildInputs"
|
||
"propagatedBuildInputs"
|
||
"propagatedNativeBuildInputs"
|
||
"shellHook"
|
||
];
|
||
in
|
||
|
||
stdenv.mkDerivation ({
|
||
inherit name;
|
||
|
||
buildInputs = mergeInputs "buildInputs";
|
||
nativeBuildInputs = packages ++ (mergeInputs "nativeBuildInputs");
|
||
propagatedBuildInputs = mergeInputs "propagatedBuildInputs";
|
||
propagatedNativeBuildInputs = mergeInputs "propagatedNativeBuildInputs";
|
||
|
||
shellHook = lib.concatStringsSep "\n" (lib.catAttrs "shellHook"
|
||
(lib.reverseList inputsFrom ++ [ attrs ]));
|
||
|
||
phases = [ "buildPhase" ];
|
||
|
||
# ......
|
||
|
||
# when distributed building is enabled, prefer to build locally
|
||
preferLocalBuild = true;
|
||
} // rest)
|
||
```
|
||
|
||
可以看到 `pkgs.mkShell { ... }` 本质上就是一个特殊的 Derivation（Nix 包），它的 `name` `buildInputs` 等参数都是可自定义的，而 `shellHook` 则是一个特殊的参数，它会在 `nix develop` 进入该环境时被执行。
|
||
|
||
如下是一份 `flake.nix` 文件，它定义了一个 nodejs 18 的开发环境：
|
||
|
||
```nix
|
||
{
|
||
description = "A Nix-flake-based Node.js development environment";
|
||
|
||
inputs = {
|
||
nixpkgs.url = "github:nixos/nixpkgs/nixos-23.05";
|
||
};
|
||
|
||
outputs = { self , nixpkgs ,... }: let
|
||
# system should match the system you are running on
|
||
# system = "x86_64-linux";
|
||
system = "x86_64-darwin";
|
||
in {
|
||
devShells."${system}".default = let
|
||
pkgs = import nixpkgs {
|
||
inherit system;
|
||
overlays = [
|
||
(self: super: rec {
|
||
nodejs = super.nodejs-18_x;
|
||
pnpm = super.nodePackages.pnpm;
|
||
yarn = (super.yarn.override { inherit nodejs; });
|
||
})
|
||
];
|
||
};
|
||
in pkgs.mkShell {
|
||
# create an environment with nodejs-18_x, pnpm, and yarn
|
||
packages = with pkgs; [
|
||
node2nix
|
||
nodejs
|
||
pnpm
|
||
yarn
|
||
];
|
||
|
||
shellHook = ''
|
||
echo "node `${pkgs.nodejs}/bin/node --version`"
|
||
'';
|
||
};
|
||
};
|
||
}
|
||
```
|
||
|
||
建个空文件夹，将上面的配置保存为 `flake.nix`，然后执行 `nix develop`（或者更精确点，可以用 `nix develop .#default`），你会发现你已经进入了一个 nodejs 18 的开发环境，可以使用 `node` `npm` `pnpm` `yarn` 等命令了。而且刚进入时，`shellHook` 也被执行了，输出了当前 nodejs 的版本。
|
||
|
||
## 进入任何 Nix 包的构建环境
|
||
|
||
现在再来看看 `nix develop`，先读下 `nix develop --help` 输出的帮助文档：
|
||
|
||
```
|
||
Name
|
||
nix develop - run a bash shell that provides the build environment of a derivation
|
||
|
||
Synopsis
|
||
nix develop [option...] installable
|
||
# ......
|
||
```
|
||
|
||
可以看到 `nix develop` 接受的参数是 `installable`，这说明我们可以通过它进入任何一个 installable 的 Nix 包的开发环境，而不仅仅是 `pkgs.mkShell` 创建的环境。
|
||
|
||
默认情况下，`nix develop` 命令会尝试 flake outputs 中的如下属性：
|
||
|
||
- `devShells.<system>.default`
|
||
- `packages.<system>.default`
|
||
|
||
而如果我们通过 `nix develop /path/to/flake#<name>` 来指定了 flake 包地址以及 flake output name，那么 `nix develop` 命令会尝试 flake outputs 中的如下属性：
|
||
|
||
- `devShells.<system>.<name>`
|
||
- `packages.<system>.<name>`
|
||
- `legacyPackages.<system>.<name>`
|
||
|
||
现在来尝试一下，首先测试下，确认我当前环境中没有 `c++` `g++` 这这些编译相关的命令：
|
||
|
||
```shell
|
||
ryan in 🌐 aquamarine in ~
|
||
› c++
|
||
c++: command not found
|
||
|
||
ryan in 🌐 aquamarine in ~
|
||
› g++
|
||
g++: command not found
|
||
```
|
||
|
||
现在通过 `nix develop` 进入到 `hello` 的构建环境，然后再次测试下：
|
||
|
||
```shell
|
||
# login to the build environment of the package `hello`
|
||
ryan in 🌐 aquamarine in ~
|
||
› nix develop nixpkgs#hello
|
||
|
||
ryan in 🌐 aquamarine in ~ via ❄️ impure (hello-2.12.1-env)
|
||
› env | grep CXX
|
||
CXX=g++
|
||
|
||
ryan in 🌐 aquamarine in ~ via ❄️ impure (hello-2.12.1-env)
|
||
› c++ --version
|
||
g++ (GCC) 12.3.0
|
||
Copyright (C) 2022 Free Software Foundation, Inc.
|
||
This is free software; see the source for copying conditions. There is NO
|
||
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
|
||
|
||
ryan in 🌐 aquamarine in ~ via ❄️ impure (hello-2.12.1-env)
|
||
› g++ --version
|
||
g++ (GCC) 12.3.0
|
||
Copyright (C) 2022 Free Software Foundation, Inc.
|
||
This is free software; see the source for copying conditions. There is NO
|
||
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
|
||
```
|
||
|
||
可以看到 `CXX` `CXXCPP` 环境变量已经被设置好了，而且 `c++` `g++` 等命令也可以正常使用了。
|
||
|
||
此外我们还可以正常调用 `hello` 这个 Nix 包的各构建阶段命令：
|
||
|
||
> 提前说明下，一个 Nix 包的所有构建阶段及其默认的执行顺序为：`$prePhases unpackPhase patchPhase $preConfigurePhases configurePhase $preBuildPhases buildPhase checkPhase $preInstallPhases installPhase fixupPhase installCheckPhase $preDistPhases distPhase $postPhases`
|
||
|
||
```shell
|
||
# 解压源码包
|
||
ryan in 🌐 aquamarine in /tmp/xxx via ❄️ impure (hello-2.12.1-env)
|
||
› unpackPhase
|
||
unpacking source archive /nix/store/pa10z4ngm0g83kx9mssrqzz30s84vq7k-hello-2.12.1.tar.gz
|
||
source root is hello-2.12.1
|
||
setting SOURCE_DATE_EPOCH to timestamp 1653865426 of file hello-2.12.1/ChangeLog
|
||
|
||
ryan in 🌐 aquamarine in /tmp/xxx via ❄️ impure (hello-2.12.1-env)
|
||
› ls
|
||
hello-2.12.1
|
||
|
||
ryan in 🌐 aquamarine in /tmp/xxx via ❄️ impure (hello-2.12.1-env)
|
||
› cd hello-2.12.1/
|
||
|
||
# generate Makefile
|
||
ryan in 🌐 aquamarine in /tmp/xxx/hello-2.12.1 via ❄️ impure (hello-2.12.1-env)
|
||
› configurePhase
|
||
configure flags: --prefix=/tmp/xxx/outputs/out --prefix=/tmp/xxx/outputs/out
|
||
checking for a BSD-compatible install... /nix/store/02dr9ymdqpkb75vf0v1z2l91z2q3izy9-coreutils-9.3/bin/install -c
|
||
checking whether build environment is sane... yes
|
||
checking for a thread-safe mkdir -p... /nix/store/02dr9ymdqpkb75vf0v1z2l91z2q3izy9-coreutils-9.3/bin/mkdir -p
|
||
checking for gawk... gawk
|
||
checking whether make sets $(MAKE)... yes
|
||
checking whether make supports nested variables... yes
|
||
checking for gcc... gcc
|
||
# ......
|
||
checking that generated files are newer than configure... done
|
||
configure: creating ./config.status
|
||
config.status: creating Makefile
|
||
config.status: creating po/Makefile.in
|
||
config.status: creating config.h
|
||
config.status: config.h is unchanged
|
||
config.status: executing depfiles commands
|
||
config.status: executing po-directories commands
|
||
config.status: creating po/POTFILES
|
||
config.status: creating po/Makefile
|
||
|
||
# build the package
|
||
ryan in 🌐 aquamarine in /tmp/xxx/hello-2.12.1 via C v12.3.0-gcc via ❄️ impure (hello-2.12.1-env) took 2s
|
||
› buildPhase
|
||
build flags: SHELL=/run/current-system/sw/bin/bash
|
||
make all-recursive
|
||
make[1]: Entering directory '/tmp/xxx/hello-2.12.1'
|
||
# ......
|
||
ranlib lib/libhello.a
|
||
gcc -g -O2 -o hello src/hello.o ./lib/libhello.a
|
||
make[2]: Leaving directory '/tmp/xxx/hello-2.12.1'
|
||
make[1]: Leaving directory '/tmp/xxx/hello-2.12.1'
|
||
|
||
# run the built program
|
||
ryan in 🌐 aquamarine in /tmp/xxx/hello-2.12.1 via C v12.3.0-gcc via ❄️ impure (hello-2.12.1-env)
|
||
› ./hello
|
||
Hello, world!
|
||
```
|
||
|
||
这种用法的主要应用场景是调试某个 Nix 包的构建过程，或者在某个 Nix 包的构建环境中执行一些命令。
|
||
|
||
## `nix shell` 与 `nix run`
|
||
|
||
与 `nix develop` 相比，这两个命令就简单且好理解很多了。
|
||
|
||
`nix shell` 用于进入到一个含有指定 Nix 包的环境并为它打开一个交互式 shell：
|
||
|
||
```shell
|
||
# hello 不存在
|
||
› hello
|
||
hello: command not found
|
||
|
||
# 进入到一个含有 hello 的 shell 环境
|
||
› nix shell nixpkgs#hello
|
||
|
||
# hello 可以用了
|
||
› hello
|
||
Hello, world!
|
||
```
|
||
|
||
`nix run` 则是创建一个含有指定 Nix 包的环境，并在该环境中直接运行该 Nix 包（临时运行该程序，不将它安装到系统环境中）：
|
||
|
||
```shell
|
||
# hello 不存在
|
||
› hello
|
||
hello: command not found
|
||
|
||
# 创建一个含有 hello 的环境并运行它
|
||
› nix run nixpkgs#hello
|
||
Hello, world!
|
||
```
|
||
|
||
因为 `nix run` 会直接将 Nix 包运行起来，所以作为其参数的 Nix 包必须能生成一个可执行程序。
|
||
|
||
根据 `nix run --help` 的说明，`nix run` 会执行 `<out>/bin/<name>` 这个命令，其中 `<out>` 是一个 Derivation 的根目录，`<name>` 则按如下顺序进行选择尝试：
|
||
|
||
- Derivation 的 `meta.mainProgram` 属性
|
||
- Derivation 的 `pname` 属性
|
||
- Derivation 的 `name` 属性中去掉版本号后的内容
|
||
|
||
比如说我们上面测试的包 hello，`nix run` 实际会执行 `$out/bin/hello` 这个程序。
|
||
|
||
## References
|
||
|
||
- [pkgs.mkShell - nixpkgs manual](https://nixos.org/manual/nixpkgs/stable/#sec-pkgs-mkShell)
|
||
- [A minimal nix-shell](https://fzakaria.com/2021/08/02/a-minimal-nix-shell.html)
|
||
- [One too many shell, Clearing up with nix' shells nix shell and nix-shell - Yannik Sander](https://blog.ysndr.de/posts/guides/2021-12-01-nix-shells/)
|