Composer plug-in

Plug - ins

Overview

You may need to change and extend Composer to add custom features. F or example, if your environment has special requirements for Composer's behavior, this does not apply to ordinary users. Or, you want to do something with Composer without affecting the average user.

In these cases, you may want to consider creating a plug-in to handle specific logic.

Create a plug-in

A plug-in is an ordinary Composer resource pack, where the main code of the plug-in is located and can rely on more other resource packs.

Plug-in package

The files in the plug-in package are the same as the normal resource pack, but must meet the following requirements:

1. The type property composer-plugin
2. The extra property must contain an element class the name of the plug-in class, including the namespace. If you have more than one plug-in in a package, you can use arrays to define class names.

In addition, you must require a special resource pack composer-plugin-api defines the composer plugin API version that is compatible with your plug-in. The current version of the composer plugin API is 1.0.0.

Instance:

{
    "name": "my/plugin-package",
    "type": "composer-plugin",
    "require": {
        "composer-plugin-api": "1.0.0"
    }
}

Plug-in class

Each plug-in must provide a class Composer\Plugin\PluginInterface interface. T he activate() class is called after the plug-in is loaded and Composer\Composer of two classes: Composer/Composer and Composer\IO\IOInterface Both objects allow you to read all configurations and manipulate all internal objects and states.

Instance:

<?php

namespace phpDocumentor\Composer;

use Composer\Composer;
use Composer\IO\IOInterface;
use Composer\Plugin\PluginInterface;

class TemplateInstallerPlugin implements PluginInterface
{
    public function activate(Composer $composer, IOInterface $io)
    {
        $installer = new TemplateInstaller($io, $composer);
        $composer->getInstallationManager()->addInstaller($installer);
    }
}

The event handler

In addition, the plug-in implements the Composer\EventDispatcher\EventSubscriberInterface in order to automatically register the event handler to EventDispatcher

The plug-in available events are as follows:

• COMMAND is called before all commands for the plug-in are loaded. It gives you access to the program's input and output.

• PRE_FILE_DOWNLOAD is triggered before the file is downloaded, which allows you to manipulate RemoteFilesystem

  A plug-in can also subscribe to script events.

Instance:

<?php

namespace Naderman\Composer\AWS;

use Composer\Composer;
use Composer\EventDispatcher\EventSubscriberInterface;
use Composer\IO\IOInterface;
use Composer\Plugin\PluginInterface;
use Composer\Plugin\PluginEvents;
use Composer\Plugin\PreFileDownloadEvent;

class AwsPlugin implements PluginInterface, EventSubscriberInterface
{
    protected $composer;
    protected $io;

    public function activate(Composer $composer, IOInterface $io)
    {
        $this->composer = $composer;
        $this->io = $io;
    }

    public static function getSubscribedEvents()
    {
        return array(
            PluginEvents::PRE_FILE_DOWNLOAD => array(
                array('onPreFileDownload', 0)
            ),
        );
    }

    public function onPreFileDownload(PreFileDownloadEvent $event)
    {
        $protocol = parse_url($event->getProcessedUrl(), PHP_URL_SCHEME);

        if ($protocol === 's3') {
            $awsClient = new AwsClient($this->io, $this->composer->getConfig());
            $s3RemoteFilesystem = new S3RemoteFilesystem($this->io, $event->getRemoteFilesystem()->getOptions(), $awsClient);
            $event->setRemoteFilesystem($s3RemoteFilesystem);
        }
    }
}

Use plug-ins

Plug-in packages are installed and loaded first, and when Composer starts, they will be loaded automatically if found in the current list of projects for which the resource pack is installed. In addition, all plug-in COMPOSER_HOME directory so that they can be loaded before the Composer global command, and the plug-in is already loaded before the local project is operated.

You can --no-plugins with composer's commands via the --no-plugins option. This may be especially useful if any plug-in causes an error while you want to upgrade or uninstall it.