Filter wordpress uploads

filter-wp-uploads.php

<?php

add_filter('wp_get_attachment_url', function($url) {
	if (getenv('USE_S3_UPLOADS')) {
		$url = 'https://' . getenv('AWS_S3_BUCKET') . '.s3.amazonaws.com' . str_replace(WP_CONTENT_URL, '', $url);
	}
	return $url;
});

add_filter('wp_calculate_image_srcset', function($sources) {
	if (getenv('USE_S3_UPLOADS')) {
		foreach ($sources as &$s) {
			$s['url'] = 'https://' . getenv('AWS_S3_BUCKET') . '.s3.amazonaws.com' . str_replace(WP_CONTENT_URL, '', $s['url']);
		}
	}
	return $sources;
});

add_filter('the_content', function($content) {
	if (getenv('USE_S3_UPLOADS')) {
		$content = preg_replace(
			"~https?\:\/\/www.site.com\/wp-content\/uploads~", 
			'https://' . getenv('AWS_S3_BUCKET') . '.s3.amazonaws.com/uploads',
			$content
		);
	}
	return $content;
}, PHP_INT_MAX);