Grav Multisite Setup, separate pages, config, cache

setup.php

<?php
/**
 * Multisite setup for subsites accessible via sub-domains.
 */

use Grav\Common\Utils;

// Get subsite name from sub-domain
$environment = isset($_SERVER['HTTP_HOST'])
    ? $_SERVER['HTTP_HOST']
    : (isset($_SERVER['SERVER_NAME']) ? $_SERVER['SERVER_NAME'] : 'localhost');
// Remove port from HTTP_HOST generated $environment
$environment = strtolower(Utils::substrToString($environment, ':'));
$folder = "sites/{$environment}";

if ($environment === 'localhost' || !is_dir(ROOT_DIR . "user/{$folder}")) {
    return [];
}

return [
    'environment' => $environment,
    'streams' => [
        'schemes' => [
            'user' => [
                'type' => 'ReadOnlyStream',
                'prefixes' => [
                    '' => ["user/{$folder}"],
                ]
            ],
            'cache' => [
                'type' => 'ReadOnlyStream',
                'prefixes' => [
                    '' => ["user/{$folder}/cache"],
                ]
            ],
            'plugins' => [
                'type' => 'ReadOnlyStream',
                'prefixes' => [
                    '' => ["user/plugins"],
                ]
            ],
            'themes' => [
                'type' => 'ReadOnlyStream',
                'prefixes' => [
                    '' => ["user/themes"],
                ]
            ],
            'images' => [
                'type' => 'ReadOnlyStream',
                'prefixes' => [
                    '' => ["user/{$folder}/images"],
                ]
            ]
        ]
    ]
];