config_path function for Lumen framework

helpers.php

<?php

if ( ! function_exists('config_path'))
{
    /**
     * Get the configuration path.
     *
     * @param  string $path
     * @return string
     */
    function config_path($path = '')
    {
        return app()->basePath() . '/config' . ($path ? '/' . $path : $path);
    }
}

Add this to lumen if you are having trouble with some laravel packages not loading the config.

Also remember to add this to your composer.json file:

"autoload": {
        ...
        "files": [
            "app/Support/helpers.php"
        ]
    },