[SOLVED] How does composer resolve package names that are not fully qualified as "webapp" or "profiler"?

How does composer resolve package names that are not fully qualified as "webapp" or "profiler"?

When you go to a Symfony project (for example created with composer create-project symfony/skeleton:"7.0.*" .) and you run composer require webapp, it will install symfony/webapp-pack.

How does composer find the package name symfony/webapp-pack when it has only been given the string webapp?

Solution

Symfony uses their own Composer plugin called Flex. It hooks into the require process.

\Symfony\Flex\PackageResolver::resolvePackageName() calls:

\Symfony\Flex\Downloader::getAliases() which makes an HTTP hit to:

https://raw.githubusercontent.com/symfony/recipes/flex/main/index.json

which contains a JSON-encoded list of Symfony-specific composer aliases:

    "web-server": "symfony/web-server-bundle",
    "web-server-bundle": "symfony/web-server-bundle",
    "webapp": "symfony/webapp-pack",
    "webhook": "symfony/webhook",
    "weblink": "symfony/web-link",

Note this is not limited to just Symfony packages. For example, also in that file:

"alice": "hautelook/alice-bundle",

So, you can do:

composer require alice