Nginx configuration for CDN

cdn.php

<?php
$host = $_SERVER["SERVER_NAME"];
$cacheDir = $_SERVER["DOCUMENT_ROOT"];
$uriPath = $_SERVER["REQUEST_URI"];
$uriPath = strtok($uriPath, "?");

$uriFull = "https://" . $host . $uriPath;
$cacheFilepath = $cacheDir . "/" . ltrim($uriPath, "/");
if(substr($cacheFilepath, -1) === "/") {
	$cacheFilepath .= "index.html";
}

$responseBody = "";

$ch = curl_init($uriFull);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
curl_setopt($ch, CURLOPT_HEADERFUNCTION, function($ch, $header):int {
	$headerLen = strlen($header);

	$header = trim($header);
	if(strlen($header) === 0) {
		return $headerLen;
	}
	if(!strstr($header, ":")) {
		return $headerLen;
	}

	header($header);
	return $headerLen;
});
curl_setopt($ch, CURLOPT_WRITEFUNCTION, function($ch, $chunk) use(&$responseBody):int {
	ob_start();
	echo $chunk;
	ob_end_flush();
	$responseBody .= $chunk;
	return strlen($chunk);
});
curl_setopt($ch, CURLOPT_HTTPHEADER, [
	"X-BrightFlair-CDN: $uriFull",
	"User-Agent: BrightFlair CDN",
]);
curl_exec($ch);
$info = curl_getinfo($ch);
curl_close($ch);

http_response_code($info["http_code"]);

if(!is_dir(dirname($cacheFilepath))) {
	mkdir(dirname($cacheFilepath), 0775, true);
}
file_put_contents($cacheFilepath, $responseBody);

default

server {
	server_name _;
	listen 80 default_server;
	listen [::]:80 default_server;
	listen 443 ssl default_server;
	listen [::]:443 ssl default_server;

	# Dynamic $ssl_server_name requires permissions to /etc/letsencrypt/archive directory.
	# Add www-data group to the directory structure with executable permissions.
	ssl_certificate /etc/letsencrypt/live/$ssl_server_name/fullchain.pem;
	ssl_certificate_key /etc/letsencrypt/live/$ssl_server_name/privkey.pem;

	root /var/www/cdn/static/$host;

	location / {
		try_files $uri $uri/index.html $uri/index.htm @cdn;
		add_header X-Debug 1234;
		sendfile on;
		sendfile_max_chunk 1m;
	}

	location @cdn {
		fastcgi_pass unix:/var/run/php/php8.0-fpm.sock;
		include fastcgi_params;
		fastcgi_param SERVER_NAME $host;
		fastcgi_param SCRIPT_FILENAME /var/www/cdn/cdn.php;
	}
}