How to get composer.phar version from inside PHP itself?

Question

is there any way to know which composer(.phar) version had generated the currently loaded autoloader?

Meaning, after running:

composer init
composer update

And creating a php file that includes the autoloader:

<?php
require 'vendor/autoload.php';

// ??

Inside this php file, Can i somehow determine which version of composer was used to generated the vendor folder (hence also the autoload.php file)?

Is there something in php, under the \Composer namespace or whatever, that tells me that (for example) a composer v2.5.5 generated the autoloader?

Running shell_exec('composer --version') is not a solution because

1. the composer binary that was used, might not be whatever the shell locates when running composer --version
2. php's shell functions (proc_open, shell_exec, exec, etc) might be disabled for security reasons

I also found \Composer\InstalledVersions::getAllRawData(), \Composer\InstalledVersions::getRootPackage() and similar, but there is no information about composer itself.

Also, final note: requiring composer/composer in my composer.json and then analyzing that package, is not the same thing...

thank you

Answer 1

I found a solution using composer's scripts, and possibly a support file.

composer.json:

{
    "scripts": {
        "pre-install-cmd": [
            "@composer --version"
        ],
        "pre-update-cmd": [
            "@composer --version"
        ],
        "post-autoload-dump": [
            "@composer --version >composer_version.log"
        ]
    }
}

From the composer docs:

To call Composer commands, you can use @composer which will automatically resolve to whatever composer.phar is currently being used

Redirecting to a file might be a way to have some information in environments where you don't have access to the entire composer install log, like GAE on GCP, for example; the problem with this particular case is that the file system is either ephemeral or read only, so who knows where the composer_version.log file ends up, if it even gets created... but that's a different question.

---

EDIT: Redirecting to a file allows for reading that file with php via a simple file_get_contents(), which was the original question.

So, to recap: composer.json

{
  "scripts":{
    "post-install-cmd": ["@composer --version >composer_version.log"]
  }
}

and some file.php:

<?php
require 'vendor/autoload.php'; // not even necessary actually

$composerVersion = file_get_contents('composer_version.log');
echo $composerVersion;

That's it.