Composer/en

Composer is a dependency manager for PHP libraries. Starting with, MediaWiki core's external library dependencies are being managed with Composer. In addition, it can be used to manage the installation of MediaWiki extensions (available since ). However this is currently not well supported. This may change in the future.

On Unix/Linux and macOS
There are multiple ways to install Composer, besides the most obvious way,.

Only Composer 1.x is supported by MediaWiki 1.31, 1.35.0 and 1.35.1. To grab the latest Composer 1.x stable release:

Composer 2.x and Composer 1.x are supported by MediaWiki >= 1.35.2 (along with the REL1_36 branch and master). To grab the latest Composer 2.x stable release:

For users on macOS, you can use Homebrew to install Composer. Note this will install version Composer 2.x, so depending on the version of MediaWiki you are using, you may need to follow the  instructions above instead to download Composer 1.x. To install using  :

If that doesn't work, or you do not have Homebrew installed, you can try:

Toolforge and the extension distributor use the copy of Composer contained in the "integration/composer" git repo.

Once Composer is installed, you can run commands via the downloaded phar:

You may want to move the phar into your path so it can be used as a normal executable:

If the mv command fails due to permissions, execute it again with sudo.

On Windows
Just download and run the installer from the download page. If you prefer manual installation, you can follow the above steps except that Windows doesn’t have wget (or APT or Homebrew) by default, and there is no /usr/local/bin directory. In these cases, you can just download composer-1.phar in your web browser and then rename it to composer.phar.

Local installation
You're not out of luck if you don't have permissions to run Composer on the server. It is also possible to download the MediaWiki folder to your local machine, install and run Composer, and transfer the files back to the server.

Composer 1.x
If you want to upgrade Composer to the latest 1.x stable (or downgrade from 2.x stable), you can use:

If the update command fails due to permissions, execute it again with sudo.

If you are on a really old version of composer, it may not have the  parameter. In this case, you might want to run  twice. The first may update it to 2.x, so the second will downgrade it to the latest version of 1.x.

Composer 2.x
If you are using Composer 1.x, and want to upgrade to Composer 2.x (and are using an appropriate version of MediaWiki, such as >= 1.35.2), you can use:

If the update command fails due to permissions, execute it again with sudo.

Usage in MediaWiki core
MediaWiki 1.25+ depends on some external libraries which are managed with Composer. Composer creates an autoloader at, which is included by.

Composer managed dependencies are bundled into tarball distributions of MediaWiki and extensions so system administrators do not need to use Composer directly. When installing MediaWiki using Git, dependencies declared in  can either be installed locally by running   or the   repository can be cloned to provide the same libraries used on the Wikimedia production cluster.

Using composer-merge-plugin
MediaWiki core "owns"  and will change the contents of that file in both tarball and Git managed updates. In order to allow local installs to use Composer to load optional libraries and/or manage extensions with Composer, a special plugin for Composer named composer-merge-plugin was developed. This plugin and the MediaWiki core  configuration allow a local deployment to add required extensions and libraries to a file   inside the root MediaWiki directory.

can also be used to install Composer managed libraries that are needed by extensions that are not installed using Composer themselves. This is only needed when the extensions are not installed from tarballs generated by Extension Distributor.

To enable Composer to discover and process the  files that may be included in any and all of your locally installed extensions, add something like this to  :

After any changes to, you need to remove   before running   again so that Composer will recalculate the dependencies and the changes will take effect.

Resources

 * List of extensions that can or must be installed with Composer
 * Composer (software)
 * Composer (software)
 * Composer (software)
 * Composer (software)
 * Composer (software)
 * Composer (software)