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Drunk with the Power of Composer Plugins

Composer is the sharpest tool in the toolbox of the modern PHP developer. The days of manual dependency management are in the distant past, and in their place we have wonderful things like Semver. Things that help us sleep at night, because we can update our dependencies without smashing rocks together.

neanderthal smashing rocks

Even though we use Composer so frequently, there’s not a lot of shared knowledge about how to extend it. It’s as if it does such a good job in its default state, that extending it isn’t worth the time or effort to do or document. Even the official docs skirt around the issue. Probably because nobody is asking for it…

Yet, recent changes have made it much easier to develop Composer plugins. Composer has also recently moved from alpha to beta, in perhaps the most conservative release cycle ever conceived. This thing that makes modern PHP possible in its current form. This cornerstone of professional PHP development. Just moved from alpha to beta.

So, today I thought we would explore the possibilities of Composer plugin development, and create a fresh bit of documentation as we go.

You can find the code for this plugin at

Getting Started

To begin, we need to create a plugin repository, separate from the application we’ll use it with. Plugins are installed like any regular dependency. Let’s create a new folder with a composer.json file:

    "type": "composer-plugin",
    "name": "sitepoint/plugin",
    "require": {
        "composer-plugin-api": "^1.0"

All of these things are important! We give this plugin a type of composer-plugin or it will never be treated as such. composer-plugin dependencies are privy to hooks in the Composer lifecycle, which we’ll tap into.

We name the plugin, so our app can require it as a dependency. You can use whatever you like here, but you’ll need to remember the name for later.

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