app.php

<?php

return [
    '*' => [],
    'dev' => [
        'container' => [
            'definitions' => [
                \craft\awss3\Fs::class => static function($container, $params, $config) {
                    $bucket = $config['bucket'];
                    $subfolder = $config['subfolder'];
                    $path = "assets/$bucket/$subfolder";

                    return new \craft\fs\Local([
                        'handle' => $config['handle'],
                        'hasUrls' => $config['hasUrls'],
                        'path' => "@webroot/$path",
                        'url' => "@web/$path",
                    ]);
                }
            ],
        ]
    ]
];