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PHP

User Guide

Overview

Several versions of PHP are available on Nix, each of which having a wide variety of extensions and libraries available.

The different versions of PHP that nixpkgs provides are located under attributes named based on major and minor version number; e.g., php81 is PHP 8.1.

Only versions of PHP that are supported by upstream for the entirety of a given NixOS release will be included in that release of NixOS. See PHP Supported Versions.

The attribute php refers to the version of PHP considered most stable and thoroughly tested in nixpkgs for any given release of NixOS - not necessarily the latest major release from upstream.

All available PHP attributes are wrappers around their respective binary PHP package and provide commonly used extensions this way. The real PHP 8.1 package, i.e. the unwrapped one, is available as php81.unwrapped; see the next section for more details.

Interactive tools built on PHP are put in php.packages; composer is for example available at php.packages.composer.

Most extensions that come with PHP, as well as some popular third-party ones, are available in php.extensions; for example, the opcache extension shipped with PHP is available at php.extensions.opcache and the third-party ImageMagick extension at php.extensions.imagick.

Installing PHP with extensions

A PHP package with specific extensions enabled can be built using php.withExtensions. This is a function which accepts an anonymous function as its only argument; the function should accept two named parameters: enabled - a list of currently enabled extensions and all - the set of all extensions, and return a list of wanted extensions. For example, a PHP package with all default extensions and ImageMagick enabled:

php.withExtensions ({ enabled, all }:
  enabled ++ [ all.imagick ])

To exclude some, but not all, of the default extensions, you can filter the enabled list like this:

php.withExtensions ({ enabled, all }:
  (lib.filter (e: e != php.extensions.opcache) enabled)
  ++ [ all.imagick ])

To build your list of extensions from the ground up, you can ignore enabled:

php.withExtensions ({ all, ... }: with all; [ imagick opcache ])

php.withExtensions provides extensions by wrapping a minimal php base package, providing a php.ini file listing all extensions to be loaded. You can access this package through the php.unwrapped attribute; useful if you, for example, need access to the dev output. The generated php.ini file can be accessed through the php.phpIni attribute.

If you want a PHP build with extra configuration in the php.ini file, you can use php.buildEnv. This function takes two named and optional parameters: extensions and extraConfig. extensions takes an extension specification equivalent to that of php.withExtensions, extraConfig a string of additional php.ini configuration parameters. For example, a PHP package with the opcache and ImageMagick extensions enabled, and memory_limit set to 256M:

php.buildEnv {
  extensions = { all, ... }: with all; [ imagick opcache ];
  extraConfig = "memory_limit=256M";
}

Example setup for phpfpm

You can use the previous examples in a phpfpm pool called foo as follows:

let
  myPhp = php.withExtensions ({ all, ... }: with all; [ imagick opcache ]);
in {
  services.phpfpm.pools."foo".phpPackage = myPhp;
}

let
  myPhp = php.buildEnv {
    extensions = { all, ... }: with all; [ imagick opcache ];
    extraConfig = "memory_limit=256M";
  };
in {
  services.phpfpm.pools."foo".phpPackage = myPhp;
}

Example usage with nix-shell

This brings up a temporary environment that contains a PHP interpreter with the extensions imagick and opcache enabled:

nix-shell -p 'php.withExtensions ({ all, ... }: with all; [ imagick opcache ])'

Installing PHP packages with extensions

All interactive tools use the PHP package you get them from, so all packages at php.packages.* use the php package with its default extensions. Sometimes this default set of extensions isn't enough and you may want to extend it. A common case of this is the composer package: a project may depend on certain extensions and composer won't work with that project unless those extensions are loaded.

Example of building composer with additional extensions:

(php.withExtensions ({ all, enabled }:
  enabled ++ (with all; [ imagick redis ]))
).packages.composer

Overriding PHP packages

php-packages.nix form a scope, allowing us to override the packages defined within. For example, to apply a patch to a mysqlnd extension, you can pass an overlay-style function to php’s packageOverrides argument:

php.override {
  packageOverrides = final: prev: {
    extensions = prev.extensions // {
      mysqlnd = prev.extensions.mysqlnd.overrideAttrs (attrs: {
        patches = attrs.patches or [] ++ [
          # ...
        ];
      });
    };
  };
}

Building PHP projects

With Composer, you can effectively build PHP projects by streamlining dependency management. As the de-facto standard dependency manager for PHP, Composer enables you to declare and manage the libraries your project relies on, ensuring a more organized and efficient development process.

Composer is not a package manager in the same sense as Yum or Apt are. Yes, it deals with "packages" or libraries, but it manages them on a per-project basis, installing them in a directory (e.g. vendor) inside your project. By default, it does not install anything globally. This idea is not new and Composer is strongly inspired by node's npm and ruby's bundler.

Currently, there is no other PHP tool that offers the same functionality as Composer. Consequently, incorporating a helper in Nix to facilitate building such applications is a logical choice.

In a Composer project, dependencies are defined in a composer.json file, while their specific versions are locked in a composer.lock file. Some Composer-based projects opt to include this composer.lock file in their source code, while others choose not to.

In Nix, there are multiple approaches to building a Composer-based project.

One such method is the php.buildComposerProject helper function, which serves as a wrapper around mkDerivation.

Using this function, you can build a PHP project that includes both a composer.json and composer.lock file. If the project specifies binaries using the bin attribute in composer.json, these binaries will be automatically linked and made accessible in the derivation. In this context, "binaries" refer to PHP scripts that are intended to be executable.

To use the helper effectively, add the vendorHash attribute, which enables the wrapper to handle the heavy lifting.

Internally, the helper operates in three stages:

  1. It constructs a composerRepository attribute derivation by creating a composer repository on the filesystem containing dependencies specified in composer.json. This process uses the function php.mkComposerRepository which in turn uses the php.composerHooks.composerRepositoryHook hook. Internally this function uses a custom Composer plugin to generate the repository.
  2. The resulting composerRepository derivation is then used by the php.composerHooks.composerInstallHook hook, which is responsible for creating the final vendor directory.
  3. Any "binary" specified in the composer.json are linked and made accessible in the derivation.

As the autoloader optimization can be activated directly within the composer.json file, we do not enable any autoloader optimization flags.

To customize the PHP version, you can specify the php attribute. Similarly, if you wish to modify the Composer version, use the composer attribute. It is important to note that both attributes should be of the derivation type.

Here's an example of working code example using php.buildComposerProject:

{ php, fetchFromGitHub }:

php.buildComposerProject (finalAttrs: {
  pname = "php-app";
  version = "1.0.0";

  src = fetchFromGitHub {
    owner = "git-owner";
    repo = "git-repo";
    rev = finalAttrs.version;
    hash = "sha256-VcQRSss2dssfkJ+iUb5qT+FJ10GHiFDzySigcmuVI+8=";
  };

  # PHP version containing the `ast` extension enabled
  php = php.buildEnv {
    extensions = ({ enabled, all }: enabled ++ (with all; [
      ast
    ]));
  };

  # The composer vendor hash
  vendorHash = "sha256-86s/F+/5cBAwBqZ2yaGRM5rTGLmou5//aLRK5SA0WiQ=";

  # If the composer.lock file is missing from the repository, add it:
  # composerLock = ./path/to/composer.lock;
})

In case the file composer.lock is missing from the repository, it is possible to specify it using the composerLock attribute.

The other method is to use all these methods and hooks individually. This has the advantage of building a PHP library within another derivation very easily when necessary.

Here's a working code example to build a PHP library using mkDerivation and separate functions and hooks:

{ stdenvNoCC, fetchFromGitHub, php }:

stdenvNoCC.mkDerivation (finalAttrs:
let
  src = fetchFromGitHub {
    owner = "git-owner";
    repo = "git-repo";
    rev = finalAttrs.version;
    hash = "sha256-VcQRSss2dssfkJ+iUb5qT+FJ10GHiFDzySigcmuVI+8=";
  };
in {
  inherit src;
  pname = "php-app";
  version = "1.0.0";

  buildInputs = [ php ];

  nativeBuildInputs = [
    php.packages.composer
    # This hook will use the attribute `composerRepository`
    php.composerHooks.composerInstallHook
  ];

  composerRepository = php.mkComposerRepository {
    inherit (finalAttrs) pname version src;
    composerNoDev = true;
    composerNoPlugins = true;
    composerNoScripts = true;
    # Specifying a custom composer.lock since it is not present in the sources.
    composerLock = ./composer.lock;
    # The composer vendor hash
    vendorHash = "sha256-86s/F+/5cBAwBqZ2yaGRM5rTGLmou5//aLRK5SA0WiQ=";
  };
})